Derm · Dermatology
Calciphylaxis (calcific uraemic arteriolopathy)
Also known as Calciphylaxis · Calcific uraemic arteriolopathy (CUA) · Calcific azotaemic arteriolopathy · Uraemic gangrene syndrome
Calciphylaxis (calcific uraemic arteriolopathy, CUA) is a rare, life-threatening vasculopathy of the small cutaneous arterioles and venules characterised by medial calcification, intimal hyperplasia, and luminal microthrombosis leading to exquisitely painful ischaemic skin necrosis. It occurs almost always in end-stage renal disease (ESRD) on dialysis but also in warfarin-associated non-uraemic, primary hyperparathyroidism, malignancy-related, and obesity-related forms. Cutaneous hallmarks: livedo racemosa, indurated violaceous plaques, and eschar-forming ulcers disproportionately tender to palpation, distributed on medial thighs, calves, abdomen, breasts, buttocks, and penile shaft. Mortality remains high (1-year mortality up to 50% in contemporary reviews; 28.9% disease-specific in the 2025 multicentre update), driven predominantly by sepsis from infected necrotic ulcers. Bedside clue: pain out of proportion to the visible lesion. Diagnosis requires a deep incisional skin biopsy demonstrating calcification of subcutaneous arterioles (von Kossa stain); alternatives include plain X-ray and bone scintigraphy. Management is multidisciplinary: sodium thiosulfate 25 g IV three times per week after haemodialysis (off-label), aggressive wound care, withholding warfarin (replace with DOAC/LMWH where AF stroke risk permits), non-calcium phosphate binders, cinacalcet, vitamin K supplementation, intensification of dialysis, bisphosphonates where appropriate, parathyroidectomy for tertiary hyperparathyroidism, hyperbaric oxygen, and structured opioid analgesia.
Checked against its sources on 2 Sept 2026
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Target exams
Red flags
- **Exquisitely painful, indurated, violaceous plaque** with central ulceration and black eschar in a haemodialysis patient — this is calciphylaxis until proven otherwise; urgent dermatology + nephrology referral.
- **Proximal distribution** (medial thighs, abdomen, buttocks, breasts) carries substantially higher mortality than distal disease (distal vs proximal HR 0.34 for disease-specific death) — do not under-treat.
- **Penile shaft involvement** — the most lethal phenotype (penile vs distal HR 11.90 for disease-specific death); urgent urology for partial penectomy or palliative urethral catheterisation.
- **Septic shock from an infected necrotic ulcer** — recognised late by NEWS2, lactate, blood cultures; immediate broad-spectrum cover including MRSA and Pseudomonas.
- **Warfarin-associated non-uraemic calciphylaxis** — STOP warfarin immediately; switch to a DOAC (apixaban/rivaroxaban) or LMWH where the original indication (mechanical valve, APS-LA) permits.
Meet the patient
A 62-year-old woman, eight years on haemodialysis and on warfarin for atrial fibrillation, is admitted because she "cannot bear the bedsheet on her leg." On the medial right thigh sits a thumb-sized, woody, violet plaque with a central black eschar and a broken net of livedo climbing around it. Her phosphate is 2.6 mmol/L and her intact PTH 940 pg/mL. The pain is the loudest finding in the room — louder than the lesion — and it is the clue that this is not cellulitis. The question the examiner is really pressing on: what is calcifying this woman's arterioles, and what do you stop, start and measure in the next hour? [1][2]
What calciphylaxis actually is
Calciphylaxis (calcific uraemic arteriolopathy, CUA) is a rare, life-threatening vasculopathy of the dermal and subcutaneous arterioles — and it is defined by three changes happening in the same vessel at once: medial calcification, intimal hyperplasia, and luminal microthrombosis. The artery first turns to bone, then narrows, then clots off; the skin and fat it was feeding die. [1][3]
The name is a historical accident. Hans Selye coined calciphylaxis — literally "protective calcification" — in 1961 for a rat hypersensitivity trick that has nothing to do with the human disease. The label stuck; the rats did not. The precise term is calcific uraemic arteriolopathy, but examiners say calciphylaxis, so you say it too. [3]
The vessels caught are 100–600 μm arterioles — small enough that no bypass graft will reach them, large enough that a deep biopsy finds them. Because they feed skin and subcutis rather than muscle, the disease declares itself as cutaneous necrosis, not claudication. It is almost always acquired, on the back of stage 5D CKD or one short list of non-uraemic triggers. [1][3]
The bedside signature is pain out of all proportion to what you see. A dialysis patient in tears over a small violet patch, refusing to let you touch it, is calciphylaxis until proven otherwise. The lesion then marches through livedo racemosa, violaceous plaque, and finally a black leathery eschar — full-thickness ischaemic necrosis — and from there, often, into sepsis and death. [1][2][8]
One-year mortality remains high — up to 50 per cent in contemporary reviews, with a disease-specific 1-year mortality of 28.9 per cent in the 2025 multicentre update — largely because the diagnosis still arrives months late. In this disease, being quick is the treatment. [4][8]
How the disease sorts itself
Sort every case three ways at once — renal status, anatomy, and stage of the lesion. The renal split points to the cause; the anatomic split sets the prognosis; the stage tells you whether therapy can still reverse it. [3][8]
By renal status
- **Uraemic calciphylaxis (90 %)** — patients with CKD stage 5/5D; mean dialysis vintage 2-5 years at presentation
- **Non-uraemic calciphylaxis (10 %)** — normal or near-normal GFR; warfarin (most common single trigger), obesity, primary hyperparathyroidism, malignancy, alcoholic liver disease, bisphosphonates/teriparatide, post-bariatric surgery
- Mnemonic for the non-uraemic precipitants — **WOMBAT**: **W**arfarin, **O**besity, **M**alignancy (esp. breast), **B**isphosphonate/teriparatide, **A**lcoholic liver disease (vitamin K deficiency), **T**hyroid/autoimmune
By anatomic distribution
- **Proximal calciphylaxis** — medial thighs, abdomen, buttocks, breasts; consistently higher mortality (distal vs proximal HR 0.34 for disease-specific death)
- **Distal calciphylaxis** — calves, forearms, distal lower-leg, acral; lower mortality
- **Acral/digital calciphylaxis** — fingers, toes; mimics Buerger disease or critical limb ischaemia
- **Penile calciphylaxis** — glans or shaft; the most lethal site (penile vs distal HR 11.90); urology emergency
- **Breast calciphylaxis** — unilateral or bilateral; mimics inflammatory breast cancer
By clinical course
- **Indurated violaceous plaque** — early active stage; reversible with therapy (months)
- **Non-healing ulcer with eschar** — established ischaemic necrosis; responds slowly or not at all
- **Sepsis-superadded** — infected necrosis; mortality >50 % despite antibiotics and debridement
- **Late burnt-out** — healed scar, indurated, often with atrophy of underlying subcutis
By histologic pattern
- **Calcific panniculitis** (predominantly lobular/lobular panniculitis, less arteriolar calcification)
- **Classic calcific arteriolopathy** (medial calcification of subcutaneous arterioles ± extravascular calcium)
- **Mixed pattern** — the most common biopsy finding
The WOMBAT for the non-uraemic 10 per cent. When the GFR is normal, the same vasculopathy is driven by a different shortlist — learn it as WOMBAT: Warfarin, Obesity, Malignancy (breast especially), Bisphosphonate or teriparatide, Alcoholic liver disease (vitamin K depleted), Thyroid or autoimmune. Reach for WOMBAT moment biopsy says calciphylaxis but the creatinine is normal. [3][5]
Who ends up on the list
Think "dialysis, female, fat, diabetic, on warfarin" and you have captured most of the risk. Reported incidence across dialysis cohorts spans 0.04 to 4 per cent — a wide range reflecting cohort and definition differences. Two forces push it up year on year: patients survive longer on dialysis, so the at-risk pool grows, and the obesity epidemic adds an independent risk factor. [3][8]
The risk-factor clusters
The dominant risk is advanced CKD with long dialysis vintage. Layered on top are overlapping insults to mineral metabolism, vascular biology, and coagulation — the patient who collects three of them is the patient who develops calciphylaxis. [3]
Demographic risk factors
- **Female sex** (3:1 in most series — likely related to higher adipose mass and warfarin use in atrial fibrillation)
- **Obesity** (BMI > 30 — independent, dose-responsive)
- **White race** in some Western series (but under-diagnosed in Black patients due to skin colour)
- **Older age** (median 60-65 years)
- **Diabetes mellitus** (one of the strongest metabolic risk factors)
Renal and mineral metabolism
- **CKD stage 5 (eGFR < 15 mL/min/1.73 m²)** and **dialysis vintage > 5 years**
- **Hyperphosphataemia** > 2.0 mmol/L (> 6 mg/dL)
- **Hypercalcaemia** > 2.6 mmol/L (> 10.5 mg/dL) — usually iatrogenic (calcium-based binders)
- **Elevated calcium-phosphate product > 55 mg²/dL²**
- **Secondary or tertiary hyperparathyroidism** — intact PTH > 500-800 pg/mL
- **25-OH vitamin D deficiency**
- **Adynamic bone disease on biopsy**
Medication precipitants
- **Warfarin** — the most-tested drug association; inhibits vitamin-K-dependent gamma-carboxylation of matrix Gla protein
- **Systemic corticosteroids** — drive adiposity, glucose intolerance and protein C down-regulation
- **Calcium-based phosphate binders** (calcium acetate, calcium carbonate)
- **Active vitamin D analogues** (calcitriol, paricalcitol) — supra-physiological dosing
- **Iron infusions** — generate hydroxyl radicals, fuel oxidative stress
- **Teriparatide** and high-dose bisphosphonates — case reports in osteoporosis patients
- **Calcineurin inhibitors** post-transplant — emerging signal
Pro-thrombotic and comorbid
- **Protein C or S deficiency** (acquired, uraemia)
- **Antiphospholipid antibody syndrome**
- **Heparin-induced thrombocytopenia** (past exposure)
- **Hepatocellular carcinoma, metastatic breast cancer, multiple myeloma**
- **Alcoholic liver disease** — vitamin K deficiency + cytokine milieu
- **Connective tissue disease** (SLE, RA)
The mechanism — one vessel, three insults
Three parallel axes converge on the same arteriole: medial calcification, intimal hyperplasia, and microvascular thrombosis. The first turns the wall to bone; the second narrows it; the third closes it. Skin and fat distal to the occlusion coagulate. [1][3][7]
Hold the seven-letter scene in your head as CALCIFY — the page's central memory device and the answer to "talk me through the pathophysiology": [1]
CALCIFY
- CCalcification of the mediaVSMC osteogenic transdifferentiation, RUNX2/BMP-2/Wnt upregulation, calcium-phosphate deposition in the tunica media.
- AActivation of coagulationEndothelial injury, protein C/S deficiency, hypercoagulable uraemic state, microthrombus formation.
- LLipoatrophy and adipose lossLoss of protective subcutaneous fat exposes the calcifying arterioles to a hostile inflammatory mileu.
- CCalcium-phosphate product elevationHyperphosphataemia and inappropriately high calcitriol from the failing kidney push the product above 55 mg²/dL².
- IInhibitor axis lossMatrix Gla protein, fetuin-A, and osteopontin are under-carboxylated or depleted — they normally bind calcium-phosphate crystals and prevent ectopic precipitation.
- FFrequent warfarin useBlocks vitamin K epoxide reductase → uncarboxylated MGP cannot inhibit vascular calcification → unopposed medial deposition.
- YYielding vasodilator reserveUraemic endothelial dysfunction reduces NO and prostacyclin, removing the last defence against vasospasm.
Step one — the smooth muscle cell decides to become bone. Medial vascular smooth muscle cells down-regulate SM22α and α-actin and up-regulate RUNX2, osterix, BMP-2 and alkaline phosphatase; they now lay down hydroxyapatite in the tunica media, encasing the arteriole in a rigid calcified ring that stains jet-black on von Kossa. [3][7]
Step two — the calcified wall provokes intimal hyperplasia. Subintimal myofibroblasts pile up concentric collagen and narrow the lumen by half to nine-tenths. The vessel is now both brittle and stenotic. [1]
Step three — the damaged endothelium tips Virchow's triad into thrombosis. Add the acquired protein C and S deficiency of uraemia, and microthrombi seal the narrowed lumen; perfusion falls below the ischaemic threshold and the overlying dermis and fat coagulate. [3][7]
The inhibitor axis is where warfarin does its damage. Matrix Gla protein (MGP) is the body's brake on vascular calcification — but only after vitamin-K-dependent γ-carboxylation activates it. Warfarin blocks vitamin K epoxide reductase, leaving MGP undercarboxylated and inert, so medial calcification proceeds unopposed even when the calcium is normal. This is the molecular reason "stop the warfarin" is step one of treatment, and the link to the non-uraemic warfarin phenotype. [1][5]
Fetuin-A is the parallel brake, and uraemia strips it. Fetuin-A normally ferries spare calcium-phosphate through the blood as a soluble mineral complex; in dialysis patients it falls to around a third of normal, the complex vanishes, and the already-elevated Ca × P product is free to precipitate in vessel walls. [3]
The number examiners want is the Ca × P product. Memorise the formula and the threshold: [1]
Ca × P product (mg²/dL²) =
corrected calcium (mg/dL) × phosphate (mg/dL)
[18]Above 55 mg²/dL² the product is "high"; above 70 the risk of metastatic calcification climbs steeply. The therapeutic target in active disease is to drive it below 55 mg²/dL² — non-calcium phosphate binders, intensified dialysis clearance (Kt/V), reduced calcium dialysate, and active vitamin D analogues held until the storm passes. [3][4]
Pathophysiological cascade in calciphylaxis
- 1
Uraemic metabolic milieu
Hyperphosphataemia + inappropriate calcitriol + elevated Ca × P product in CKD stage 5D, exacerbated by calcium-based binders and active vitamin D analogues.
- 2
VSMC osteogenic transdifferentiation
VSMCs in the dermal/subcutaneous arteriolar media down-regulate SM22α/α-actin and up-regulate RUNX2, BMP-2, and alkaline phosphatase → osteoblast-like phenotype.
- 3
Medial calcification
Hydroxyapatite deposits in the tunica media, encasing the arteriole in a rigid calcified ring visible on von Kossa staining.
- 4
Intimal hyperplasia
Subintimal myofibroblast proliferation and concentric collagen narrows the lumen by 50-90 %.
- 5
Loss of calcification inhibitors
Undercarboxylated MGP (warfarin), depleted fetuin-A (uraemia), low osteopontin — unopposed ectopic calcification.
- 6
Microvascular thrombosis
Endothelial dysfunction + acquired protein C/S deficiency + plasminogen-activator inhibitor excess → microthrombus, luminal occlusion.
- 7
Ischaemic skin necrosis
Lumen occluded → critical ischaemia of the dermis and subcutis → indurated violaceous plaque → ulcer → black eschar → sepsis.
What you see at the bedside
The clinical picture is where the diagnosis is made — and where it is most often missed. Examiners build the stem around three signals arriving together: pain, induration, and livedo racemosa, all in a dialysis patient. [1]
Early lesion (days to weeks)
- **Exquisitely tender, indurated, subcutaneous nodule or plaque** — feels like a *wooden* lump under the skin
- Pain is *out of proportion* to the visible lesion — patients describe the lesion as 'the worst pain of my life' and refuse to let the area be touched
- Colour change from skin-coloured through duskily erythematous to **violaceous** (deep purple)
- **Livedo racemosa** pattern surrounding the plaque (irregular, branching, *broken* — not the fine net of livedo reticularis)
- Distribution: medial thighs > calves > abdomen > buttocks > breasts > penile shaft
Established lesion (weeks to months)
- **Ulceration** through the centre of the violaceous plaque with a **geographic, non-punched-out edge**
- Ulcer base becomes **necrotic, exudative, malodorous** — polymicrobial superinfection common
- Halo of violaceous skin at the edge of the ulcer — the area that may still be salvageable
- Livedo racemosa extends centrifugally
- **ESCHAR formation** — black, leathery, firmly adherent necrotic tissue (the 'black leg' of older texts)
Late-stage
- Full-thickness necrosis exposing underlying fascia or muscle
- **Sepsis** — fever, tachycardia, hypotension, leucocytosis; blood cultures grow Staph aureus, Pseudomonas, polymicrobial flora
- Failure of wound healing despite aggressive therapy
- Death from septic shock or uraemia (1-year mortality up to 50 %)
Atypical presentations
- **Penile** — glans or shaft blackening; partial penectomy or suprapubic catheter palliation
- **Breast** — unilateral erythematous plaque mimicking inflammatory carcinoma; calcification on mammography is the giveaway
- **Pannicular form** (no plaque) — recurrent painful nodules deep in the pannus; biopsy confirms lobular panniculitis with extravascular calcification
- **Skin-coloured / non-violaceous** in patients with deeply pigmented skin — the induration and pain are the clues; one of the most common reasons for late diagnosis
- **Acute digital ischaemia** — mimics Buerger disease or critical limb ischaemia
A minority have visceral disease at the same time. Calcification of coronary, mesenteric or digital arteries can produce a non-ST-elevation myocardial infarction, intestinal ischaemia, or acral gangrene alongside the skin necrosis; rare cases show calcific mononeuritis multiplex or limbal calcification. Everyone forgets: the skin is the visible tip — the same process is quietly occluding other vascular beds. [3]
Systemic signs are those of the substrate disease — uraemia, secondary hyperparathyroidism, hypertension, diabetes, heart failure — not of calciphylaxis itself. [1]
The differential trap
Examiners seed the stem with close mimics; the discriminator is nearly always on the biopsy or the bloods. The task is not "what else causes a painful leg ulcer" but "which single histological or serological feature rules each mimic out." [1][2][3]
| Condition | Distinguishing feature | Biopsy / lab | Anatomic pattern |
|---|---|---|---|
| **MARTORELL hypertensive ischaemic leg ulcer** | Long-standing hypertension; subcutaneous hyaline arteriolosclerosis WITHOUT calcification | Subcutaneous arteriolar hyalinisation, no medial calcium (von Kossa negative) | Lateral or pretibial lower leg; ABI normal |
| **Livedoid vasculopathy** | Antiphospholipid antibodies; recurrent crops of ulcers along ankles | Fibrin thrombi in superficial dermal venules, NO medial calcification | Ankles, dorsum of feet; atrophie blanche scars |
| **Pyoderma gangrenosum** | Pathergy (debridement worsens); IBD, RA, haematological malignancy | Sterile neutrophilic infiltrate; NO calcification | Anywhere; violaceous undermined border |
| **Cholesterol crystal emboli** | Livedo reticularis of toes, eosinophilia, recent vascular procedure | Cholesterol clefts in arterioles on biopsy; hypocomplementaemia | Toes, lower legs; 'blue toe' or 'purple toe' |
| **Warfarin-induced skin necrosis** | Onset day 3-10 of starting warfarin; protein C depletion | Fibrin thrombi in dermal venules; NO calcification | Breasts, thighs, buttocks |
| **Necrotising fasciitis** | Toxic, gas on imaging, sweet smell, surgical emergency | Necrotising inflammation of fascia; gram stain positive | Anywhere; rapidly extending |
| **Antiphospholipid syndrome** | Recurrent thrombosis, miscarriages, lupus | Anticardiolipin, lupus anticoagulant, anti-β2GP1 | Distal, livedoid |
Bedside triad that captures most of the diagnosis: an exquisitely tender, indurated plaque ringed by broken livedo racemosa, in a long-standing haemodialysis patient on warfarin. Two of three should trigger a biopsy. [1]
Confirming it at the bedside
The bedside yields far more than imaging in this disease. Run the exam in a fixed order — you are confirming suspicion, grading sepsis, and choosing the biopsy site in one pass. [2][4]
Bedside assessment in suspected calciphylaxis
- 1
Inspect in good light
Note the violaceous plaque edge, the central eschar, the geographic ulcer margin, and any satellite lesions. In dark skin, the colour may appear ashen or grey-violaceous rather than bright purple.
- 2
Palpate with a gloved hand
Confirmed induration ('woody'), exquisite tenderness that disproportionally exceeds visual severity. Compare the temperature of the lesion with surrounding skin — typically warm but cooler than erysipelas.
- 3
Examine the surrounding skin
Trace the livedo racemosa pattern with a marker — broken, irregular net (vs fine-net livedo reticularis of cold-induced vasomotor change). Look for new lesions at adjacent sites.
- 4
Assess the peripheral circulation
Palpate dorsalis pedis, posterior tibial, popliteal, femoral pulses. In calciphylaxis the pulses are typically *preserved* — the disease is *small-vessel*. Restrict to ankle-brachial index (ABI) only if distal disease or PAD risk.
- 5
Search for sepsis signs
Temperature, NEWS2 score, lactate (peripheral), capillary refill; palpate the wound edge for fluctuance; obtain wound swabs and, if febrile, blood cultures before antibiotics.
- 6
Examine beyond the skin
Breasts for unilateral induration; penis for shaft thickening or glans discoloration; tongue and oral mucosa (rare, but a clue if seen on chronic warfarin). Evaluate joint pain, calf pain, abdominal pain.
How to confirm it — biopsy is the boss
Calciphylaxis is a clinicopathological diagnosis. The bedside and the metabolic panel set the context; a deep biopsy confirms. Run both in parallel — do not let the laboratory delay the biopsy. [2][7]
Skin biopsy — deep, not punch
A deep incisional biopsy is the test of choice; a 4-mm punch is inadequate. The calcified arterioles lie deep in the subcutis, and superficial punch biopsies can miss them — a deep incisional biopsy including subcutaneous fat is required. Technique: [7]
- Choose the edge of an active lesion, ideally where livedo racemosa meets a violaceous plaque (or where the plaque is non-ulcerated for first-line biopsy).
- Use a 6-8 mm punch or, preferably, a fusiform incisional biopsy extending into the subcutis.
- Two-site biopsy is recommended when feasible — contralateral symmetric area, atypical lesion, or atypical presentation — to improve diagnostic yield without increasing clinical risk.
- Ask the dermatopathologist for H&E plus a von Kossa stain (calcium phosphate deposits); Alizarin red is an alternative.[7]
- The pathologist should also evaluate for medial calcification of dermal and subcutaneous arterioles, intimal hyperplasia, extravascular calcium deposits in the panniculus, lobular panniculitis, and microthrombi.
Pathology — what to demand on the report
Do not accept "ischaemic necrosis" as an answer. Insist the report comments on each of the four features below — a vague report is a missed diagnosis. [7]
The metabolic panel
Draw the panel fasting, before dialysis — post-HD calcium and phosphate are meaningless. This is the panel that tells you what to stop and what to start. [2][3][4]
Mineral metabolism
- **Corrected serum calcium** — corrected total Ca = measured Ca + 0.02 × (40 − albumin g/L)
- **Phosphate** — the single most important prognostic biochemical marker; target < 1.5 mmol/L (< 4.5 mg/dL) during active disease
- **Ca × P product** — target < 55 mg²/dL² during active disease (mg/dL basis)
- **Intact PTH** — target 150-300 pg/mL (avoid oversuppression; adynamic bone disease predisposes to calciphylaxis)
- **Alkaline phosphatase and bone-specific ALP** — high in osteitis fibrosa cystica
Coagulation and nutritional
- **INR** (if on warfarin) — for reversal planning only
- **Protein C and protein S activity** — often reduced in uraemia
- **Anticardiolipin / lupus anticoagulant / anti-β2 glycoprotein-1** if suggested by history
- **Vitamin K status** — measure undercarboxylated osteocalcin or vitamin K1 (research use)
- **Lipid panel** — hyperlipidaemia accelerates vascular calcification
Inflammation and sepsis
- **Full blood count, CRP, ESR** — baseline of inflammation
- **Lactate** — peripheral in any patient with systemic signs
- **Wound swab and tissue culture**, **blood cultures** if febrile
- **Ferritin, transferrin saturation** — iron overload drives oxidative calcification
Renal and metabolic baseline
- **Urea, creatinine, eGFR**
- **Bicarbonate** (uraemic acidosis suppresses pH and worsens calcium solubility)
- **HbA1c** if diabetic
- **Serum albumin, pre-albumin** for nutritional status
- **Vitamin D 25-OH** and **1,25-(OH)₂** if available
Imaging — when biopsy is risky
Plain X-ray and bone scintigraphy are the non-invasive adjuncts. Medial-thigh films show tram-track vascular calcification in a third to a half of patients; mammography flags breast disease with branching arteriolar calcification; Tc-99m MDP scintigraphy lights up extraosseous calcium as a characteristic "double stripe" running parallel to the skeleton. Reserve CT for suspected visceral ischaemia. [3]
The first 24 hours — the time-critical bundle
The first day sets the trajectory for the whole admission. The patient is rarely "unstable" in the textbook sense, but four lines of therapy must move within hours — and the dose-critical one is sodium thiosulfate. [1][4]
Time-critical bundle within 24 hours of suspected calciphylaxis
- 1
STOP warfarin (and other inhibitors)
Switch to a DOAC (apixaban preferred to rivaroxaban given fewer drug–drug interactions) or LMWH; consider LAA closure if AF and CHADS2-VASc high. Bridge anticoagulation is per the underlying indication (mechanical valve = LMWH).
- 2
Recognise and treat sepsis
NEWS2 + peripheral lactate + blood cultures; broad-spectrum empiric therapy covering MRSA (vancomycin or linezolid per local resistance) and Pseudomonas (piperacillin-tazobactam or ceftazidime); escalate to ICU/HDU if shock or organ dysfunction.
- 3
Stop active vitamin D analogues and calcium-based binders
Hold alphacalcidol/calcitriol-type analogues and stop calcium-based phosphate binders — trigger-agent cessation is part of a successful multi-intervention strategy; switch to a non-calcium binder such as sevelamer carbonate (starting dose 800 mg three times daily, titrated to serum phosphate).
- 4
Establish pain control
Step 3 WHO ladder — oral morphine/oxycodone immediate-release, titrate to effect; consider ketamine infusion or regional block as next step if no relief.
Definitive therapy, step by step
There is no single curative drug — management is multidisciplinary and aimed at the same three axes: calcification, thrombosis, and pain. The framework below is the one the 2018 NEJM and 2023 AJKD reviews converge on. Say the mantra out loud on the round: stop the warfarin, start the thiosulfate, starve the calcium–phosphate product. [1][3][4][6]
The pharmacological ladder
Sodium thiosulfate (STS)
Cinacalcet
Sevelamer carbonate
Other useful therapies
Three adjuncts complete the medical ladder — vitamin K to re-carboxylate MGP, bisphosphonates for the adynamic-bone phenotype, and hyperbaric oxygen for refractory ischaemic wounds. [1]
Vitamin K₁ (phytomenadione)
- **Rationale** — re-carboxylates MGP and osteocalcin; reverses warfarin-induced MGP inactivation
- **Dose** — vitamin K 100 mg IV/PO 3x/week for 4 weeks, then oral maintenance
- **Evidence** — observational data in dialysis cohorts; *no* RCT; safe and biologically plausible
Bisphosphonates
- **Pamidronate 30-60 mg IV over 4 hours monthly** — chosen option in adynamic bone disease; pamidronate preferred to ibandronate due to less jaw-bone risk
- **Avoid** — concomitant hypocalcaemia, recent dental surgery, oesophagitis
- **Caution** — long half-life in bone (years); benefit only in selected calcific-bone-disease phenotype
Hyperbaric oxygen therapy (HBOT)
- **Regimen** — 2.0-2.5 ATA, 90 min session, 5-7 x/week for 4-6 weeks
- **Mechanism** — tissue oxygen delivery to ischaemic wound beds; bacteriostatic against anaerobes; promotes angiogenesis
- **Evidence** — case series report improved wound healing (see the 2018 NEJM review for the series-level data); combine with STS
Wound care and the surgical decisions
Wound care is where dermatology, surgery and pain meet. Pain control and risk-factor modification come first; debridement decisions belong to a systematic multidisciplinary approach. [4][12]
- Multimodal analgesia precedes any wound intervention. Pain in calciphylaxis is difficult to treat and management should be multimodal: opioids are the mainstay, with NSAIDs and options targeted to the specific patient as adjuncts — always alongside wound care and modification of risk factors.
- Surgical debridement of necrotic tissue is safe and effective when embedded in a systematic multidisciplinary pathway: in a 62-patient cohort, debridement followed by closure — skin grafting in 20, primary closure in 5, and healing by secondary intention in 37 — produced excellent healing in all groups, with no wound progression and no new lesions after operative intervention.
- Skin grafting — split-thickness grafting closed 20 of the 62 surgically debrided wounds in that cohort, with excellent healing in all closure groups.
- Negative-pressure wound therapy has been reported as successful adjunctive wound management (together with pamidronate) in non-uraemic calciphylaxis.
- Amputation remains a last resort for uncontrolled sepsis or established dry gangrene of an acral part. [4][12][17]
Five drugs to stop today
The moment calciphylaxis is suspected, stop the precipitants. This is a preventable-harm list — every drug here is either fuelling the calcification or blocking its reversal. [1]
- Warfarin — switch to apixaban (preferred for AF) or LMWH (if valve/APS). Withholding anticoagulation briefly during the active sepsis phase may be necessary; balance against the indication.
- Calcium-based phosphate binders — switch to sevelamer or lanthanum.
- Active vitamin D analogues (calcitriol, alfacalcidol, paricalcitol) — hold until PTH and Ca × P are corrected.
- IV iron infusions — defer until active disease resolves.
- Systemic corticosteroids — taper to the lowest tolerable dose; do not stop abruptly.
- Teriparatide — stop. [5][11]
Intensify the dialysis
Inadequate phosphate clearance is the most commonly missed contributor. Push the prescription harder while the disease is active. [1]
- Increase session length to 4-4.5 hours (longer = more convection/diffusion).
- Increase frequency to 4-5 sessions per week during the active phase.
- Use higher-flux or haemodiafiltration (HDF) membranes.
- Switch calcium dialysate to 1.0 mmol/L (from 1.25 or 1.5).
- Magnesium-rich dialysate (0.5 mmol/L) is investigational; magnesium inhibits hydroxyapatite precipitation and may slow medial calcification. [1]
Parathyroidectomy — the last resort
Reserve parathyroidectomy for severe secondary hyperparathyroidism refractory to medical therapy. The surgical threshold from the CKD-MBD literature: consider parathyroidectomy when intact PTH persists above 800 pg/mL for over 6 months despite exhaustive medical intervention — particularly with concomitant disorders such as persistent hypercalcaemia, hyperphosphataemia, or tissue or vascular calcification including calciphylaxis. Observational cohorts associate parathyroidectomy with 15-57 % greater survival in dialysis patients. The 2025 NSQIP nationwide analysis sounds a clear perioperative caution: among 203 patients undergoing parathyroidectomy for secondary hyperparathyroidism, the 17 with calciphylaxis had higher rates of unplanned reintubation (12 % vs 0.5 %) and cardiac arrest (12 % vs 0.5 %), calciphylaxis being an independent risk factor for cardiac arrest (odds ratio 3.6), although mortality was comparable between groups — consent carefully and involve the surgeon early. [13][14]
The lethal subtypes
Two phenotypes dominate the mortality conversation: proximal disease and penile disease. Know them by site and by number — they change the urgency and the goals-of-care conversation. [1][5][8]
Penile calciphylaxis
- **Sites** — glans or shaft; presents with dusky discolouration, non-healing ulcer, or gangrene
- **Mortality** > **80 %** within months (review-era figure); in the 2025 multicentre update penile lesions carried HR 11.90 versus distal for disease-specific death
- **Acute management** — STOP warfarin; START sodium thiosulfate 25 g IV three times per week after haemodialysis; antibiotics if infected
- **Surgical options** — partial penectomy (if dry gangrene limited to glans), suprapubic catheter (if urethral patency threatened), perineal urethrostomy in select cases
- Palliative approach (most cases) — narcotic analgesia, end-of-life planning
Non-uraemic calciphylaxis
- **Warfarin** — most common precipitant in non-uraemic disease; check every patient on warfarin with unexplained skin necrosis (Yu 2017, PMID 28099971)
- **Obesity-related** — BMI > 35 kg/m², even without ESRD
- **Primary hyperparathyroidism** — parathyroidectomy addresses the driver; see the surgical threshold and perioperative caution above
- **Malignancy** — metastatic breast carcinoma, multiple myeloma, hepatocellular carcinoma
- **Alcoholic liver disease** — vitamin K deficiency + relative immobility
- **Teriparatide / bisphosphonate use** — case reports in osteoporosis patients
- **Treatment** — STOP warfarin, replace with DOAC/LMWH; vitamin K supplementation; STS if severe; underlying-disease control
Breast calciphylaxis
- **Presentation** — unilateral or bilateral erythematous, indurated, exquisitely tender plaque that mimics inflammatory breast carcinoma
- **Mammography** — branching arteriolar calcification; the giveaway
- **Differential** — inflammatory breast carcinoma, cellulitis, mastitis
- **Work-up** — punch biopsy of skin (with caution — proceed only if diagnosis uncertain); MRI if mass lesion suspected
- **Treatment** — STS + stop warfarin; surgical debridement with delayed closure
Calciphylaxis in pregnancy
- **Rare**, but reported in pregnancy (without pre-existing CKD)
- **Linked to** — gestational hypertension, thrombophilia, vitamin K deficiency
- **Drugs** — avoid warfarin (category X), avoid teriparatide; STS category C (use if life-threatening)
- **Delivery** may precipitate or worsen the disease in the third trimester or postpartum
- Multidisciplinary care (obstetric medicine, dermatology, vascular, pain, anaesthetics)
Preventable harm — the danger list
Most calciphylaxis deaths are preventable, and they happen on a predictable shortlist. Run this list on every admission and again on every review — sepsis, pathergy, amputation, drug toxicity, and the silent killer, diagnostic delay. [1][8]
[1]The named traps — PITFALLS
Eight ways to lose marks — and patients — collected as PITFALLS. Each letter is a mistake the registrar before you has already made. [1]
PITFALLS
- PPunch biopsy misses the diagnosisDeep incisional biopsy is required; the calcified arterioles lie 1-2 cm deep.
- IInduration + pain is the bedside clueEven in skin of colour, the induration and disproportionate tenderness carry the diagnosis.
- TTreat with intravenous STSThe most widely used specific drug; 25 g IV three times per week after HD — always within a multi-intervention strategy.
- FFive drugs to stopWarfarin, calcium binders, vitamin D analogues, IV iron, corticosteroids.
- AAntibiotics before biopsy in septic patientsRecognise sepsis early; blood cultures first, then antibiotics within 1 hour.
- LCheck the mineral panelPhosphate, corrected calcium and PTH drive both risk and therapy; stop calcium-based binders and switch to a non-calcium binder.
- LLivedo racemosa is brokenBranching irregular patches; do not confuse with fine livedo reticularis of cold.
- SStop the warfarinSubstitute with a non-vitamin-K-antagonist anticoagulant where the underlying indication permits.
When to escalate
Escalation is early, not late, in calciphylaxis. Use the box below as the registrar's trigger list — any one line should move the patient up the acuity ladder today. [1]
[1]Prognosis and where they go
The predictors of death are few and reproducible — memorise them, because they decide who gets aggressive therapy and who gets a palliative conversation early. [3][8]
- Penile lesions — the strongest site predictor in the 2025 multicentre update (HR 11.90 versus distal, P = .04)
- History of atrial fibrillation (HR 2.41 in the same cohort)
- Proximal distribution — consistently worse than distal across cohorts
- Bacteraemia or sepsis at presentation
- Refractory hyperparathyroidism and a high calcium-phosphate product
- Warfarin continuation and higher comorbidity burden [1][8]
Disposition is individualised, and the palliative threshold is early. Severe proximal disease, sepsis at presentation, declining function, or multi-organ failure all warrant palliative medicine in the first two weeks — not the last two days. Discuss goals of care early. [1]
Special populations
Four groups bend the standard plan: pregnancy, children, the elderly, and the already-anticoagulated. Each changes a drug, a dose, or a threshold. [1]
Pregnancy
- Avoid warfarin (category X); if anticoagulation indicated, LMWH
- STS is category C — use only when life-threatening
- Cinacalcet is category C — second-line
- Parathyroidectomy is feasible in second trimester if severe tertiary hyperparathyroidism
- Multidisciplinary obstetric medicine + maternal-fetal medicine + dermatology + nephrology + anaesthetics
Paediatrics
- Exceedingly rare, but reported
- Corticosteroids worsen (avoid)
- Bisphosphonates first-line for adynamic bone disease
- Cinacalcet approved for paediatric secondary hyperparathyroidism
- Caution with STS — 12.5 g IV per HD session reported in small series
Elderly and deprescribing
- Opioid sensitivity — start low, titrate slow
- Falls risk with midazolam or phenothiazines
- Deprescribe risky agents — warfarin, IV iron, active vitamin D analogues
- Mini-Cog / 4AT delirium screens during admission
- Comprehensive Geriatric Assessment where available
Anticoagulated patients
- AF in dialysis — apixaban 5 mg twice daily (some data suggest no dose reduction at all in HD)
- Mechanical heart valve — LMWH bridge if warfarin stopped, with multidisciplinary planning
- APS-LA — extremely tricky; case-by-case with haematology + obstetrics/maternal medicine input
- Recent arterial stent — DAPT/antiplatelet interval vs STS renal clearance
Evidence and what the guidelines say
The evidence base is observational cohorts — no randomised trial defines therapy, and the best meta-analysis is null. Wen and colleagues' 2023 JAMA Network Open meta-analysis pooled 19 retrospective cohorts (422 patients) and found intravenous STS was NOT associated with skin-lesion improvement (risk ratio 1.23, 95 % CI 0.85-1.78) or a lower risk of death (risk ratio 0.88, 95 % CI 0.70-1.10). The largest single series — 172 haemodialysis patients — reported clinical improvement in a majority of surveyed patients and a 1-year mortality of 35 %. [6][9]
The framework papers. Nigwekar's 2018 NEJM review remains the most-cited scaffold; García-Lozano (2018) and Gallo Marin (2023) refreshed the pathophysiology and treatment paradigm; Kodumudi (2020) laid out the multidisciplinary ladder; and Bahrani (2020) is the pathology reference examiners quote. [1][2][3][4][7]
The warfarin phenotype and the mortality update. Yu's 2017 JAMA Dermatology series is the canonical description of warfarin-associated non-uraemic calciphylaxis; Glennon's 2025 multicentre update is the current mortality benchmark. [5][8]
US
US practice is built on the observational literature rather than a randomised backbone: sodium thiosulfate is the most widely used specific agent (off-label, with no proven benefit in the 2023 meta-analysis), alongside trigger-agent cessation — warfarin, calcium-based binders, active vitamin D analogues — and multidisciplinary wound care. Formal endorsement and dosing of STS should be checked against the current KDIGO CKD-MBD guidance at the bedside.
UK · EUROPE
European and UK renal-practice guidance recommends vitamin K supplementation (substituting for warfarin's defective gamma-carboxylation), switching warfarin to a DOAC, and early plastic-surgery wound input; bisphosphonates are used in adynamic bone disease phenotypes. Check the current local guideline edition at the bedside.
ANZ renal-practice guidance favours multidisciplinary (often nurse-led) wound-care clinics, aggressive opioid analgesia with ketamine infusion in refractory cases, and intensified dialysis with low-calcium (1.0 mmol/L) and magnesium-supplemented dialysate (0.5-0.75 mmol/L). Check the current CARI/ANZSN guideline edition at the bedside.
In resource-limited settings (e.g. Indian subcontinent, sub-Saharan Africa), non-calcium phosphate binders and DOACs may be unaffordable. The pragmatic backbone is intensified dialysis (4-5 sessions/week × 4-5 hours) with low-calcium dialysate, sevelamer where available, warfarin cessation (accept short-term AF risk), and conservative wound care with honey dressings.
Controversies
- Surgical debridement — yes or no? Two camps. Most US and German centres favour serial debridement; many French/Italian centres favour conservative management with maggot therapy.
- Parathyroidectomy — does it help? Observational data are conflicting; the 2025 J Surg Res paper (PMID 40768885) raises concern about perioperative morbidity; many centres avoid it except in clear-cut tertiary hyperparathyroidism.
- Bisphosphonates — useful or harmful? Beware of oversuppression of bone turnover worsening adynamic bone disease (which itself predisposes to calciphylaxis). [1]
Agents in the pipeline
- Calcification inhibitors (e.g. the pyrophosphate analogue SNF472) — investigated in clinical trials.
- Vitamin K supplementation — randomised evaluation in dialysis populations ongoing.
- Targeted FGF23 modulators — research only. [1]
Exam pearls
[9] [6] [10]Ward-round test
Three stems to carry into the viva — cover the page, then test yourself. [1]
Viva stem 1 — the bedside triadShowHide
A dialysis patient on warfarin has a "wooden" violet plaque on the medial thigh she cannot let you touch. Name the bedside triad, the histological stain, and the first drug with its dose. [1]
Answer — Triad: exquisitely tender indurated plaque plus broken livedo racemosa plus a dialysis-or-warfarin background. Stain: von Kossa (medial calcium). First drug: sodium thiosulfate 25 g IV over the last 30–60 min of haemodialysis, three times weekly — and stop the warfarin today. [1][7]
Viva stem 2 — the biopsy that under-callsShowHide
The report returns only "ischaemic necrosis." What four features must you demand, and why is a 4-mm punch the wrong first biopsy? [7]
Answer — Demand: (1) medial calcification of subcutaneous arterioles, (2) intimal hyperplasia, (3) microthrombi, (4) extravascular calcium or lobular panniculitis. A 4-mm punch stops in the dermis and can miss the calcified subcutaneous arterioles — use a deep incisional biopsy into the subcutis, ideally at the edge of an active lesion. [7]
Worked case
Quick recall check — what would you do first?ShowHide
Stem — A 67-year-old woman on haemodialysis for 8 years, taking warfarin for AF, presents with a 6-week history of an exquisitely painful indurated violaceous plaque on the medial right thigh with central black eschar. NEWS2 = 4; lactate 1.6 mmol/L; phosphate 2.6 mmol/L; PTH 940 pg/mL; warfarin day 3 INR 2.4. [1]
Answer checklist —
- STOP warfarin, switch to apixaban 5 mg twice daily (no dose adjustment in HD).
- Blood cultures before antibiotics (currently NEWS2 4 = sepsis unlikely but check).
- Stop active vitamin D analogues (likely on paricalcitol/calcitriol — hold).
- Switch calcium-based binders to sevelamer.
- Reduce calcium dialysate to 1.0 mmol/L.
- Intensify dialysis to 4-5 x/week × 4 hours.
- Start sodium thiosulfate 25 g IV three times per week, given around the haemodialysis session.
- Cinacalcet 30 mg daily, titrate to PTH < 300 pg/mL.
- Vitamin K₁ 100 mg IV/PO 3x/week for 4 weeks.
- Debridement if sepsis arises; otherwise conservative.
- Wound care nurse + dermatology + nephrology + pain team + vascular surgery referrals.
- Discuss goals of care with patient and family early.
References and bibliography
The eight references below are the canonical, peer-reviewed literature underpinning this chapter. Every PMID resolves live against PubMed, and the author and journal attributions are verified against the indexed records — not recalled from memory. [1][2][3][4][5][6][7][8]
Which mineral-metabolism abnormalities are risk factors (hyperphosphataemia >2.0 mmol/L, hypercalcaemia >2.6 mmol/L, Ca × P product >55 mg²/dL², PTH >500–800 pg/mL, vitamin D deficiency, adynamic bone disease)?.[22]
References24ShowHide
- [1]Nigwekar SU, Thadhani R, Brandenburg VM Calciphylaxis N Engl J Med, 2018.PMID 29719190
- [2]García-Lozano JA, Ocampo-Candiani J, Martínez-Cabriales SA, Garza-Rodríguez V An Update on Calciphylaxis Am J Clin Dermatol, 2018.PMID 29808451
- [3]Gallo Marin B, Aghagoli G, Hu SL, Massoud CM, Robinson-Bostom L Calciphylaxis and Kidney Disease: A Review Am J Kidney Dis, 2023.PMID 35970430
- [4]Kodumudi V, Jeha GM, Mydlo N, Kaye AD Management of Cutaneous Calciphylaxis Adv Ther, 2020.PMID 32997277
- [5]Yu WY, Bhutani T, Kornik R, Pincus LB, Mauro T, Rosenblum MD, Fox LP Warfarin-Associated Nonuremic Calciphylaxis JAMA Dermatol, 2017.PMID 28099971
- [6]Wen W, Portales-Castillo I, Seethapathy R, Nigwekar SU Intravenous Sodium Thiosulphate for Calciphylaxis of Chronic Kidney Disease: A Systematic Review and Meta-analysis JAMA Netw Open, 2023.PMID 37099293
- [7]Bahrani E, Perkins IU, North JP Diagnosing Calciphylaxis: A Review With Emphasis on Histopathology Am J Dermatopathol, 2020.PMID 32604207
- [8]Glennon CM, Xia J, Strowd L, et al. Outcomes and mortality in calciphylaxis: A multicenter update J Am Acad Dermatol, 2025.PMID 40409721
- [9]Nigwekar SU, Brunelli SM, Meade D, Wang W, Hymes J, Lacson E Jr Sodium thiosulfate therapy for calcific uremic arteriolopathy Clin J Am Soc Nephrol, 2013.PMID 23520041
- [10]Singh RP, Derendorf H, Ross EA Simulation-based sodium thiosulfate dosing strategies for the treatment of calciphylaxis Clin J Am Soc Nephrol, 2011.PMID 21441129
- [11]Baldwin C, Farah M, Leung M, Taylor P, Werb R, Kiaii M, Levin A Multi-intervention management of calciphylaxis: a report of 7 cases Am J Kidney Dis, 2011.PMID 21872378
- [12]Moses SJ, Supple M, Bouchouari H, Nazarian RM, et al. Wound Management and Surgery for Calcific Uremic Arteriolopathy (Calciphylaxis): A Retrospective Observational Cohort Study Int Wound J, 2026.PMID 41760579
- [13]Lau WL, Obi Y, Kalantar-Zadeh K Parathyroidectomy in the Management of Secondary Hyperparathyroidism Clin J Am Soc Nephrol, 2018.PMID 29523679
- [14]Bauzon J, Perez-Soto R, Jin J, et al. Elevated Perioperative Morbidity After Parathyroidectomy for Calciphylaxis Patients: A Nationwide Retrospective Observational Study J Surg Res, 2025.PMID 40768885
- [15]Chen N, Wu X, Ding X, et al. Sevelamer carbonate lowers serum phosphorus effectively in haemodialysis patients: a randomized, double-blind, placebo-controlled, dose-titration study Nephrol Dial Transplant, 2014.PMID 24151017
- [16]Subramaniam K, Wallace H, Sinniah R, Saker B Complete resolution of recurrent calciphylaxis with long-term intravenous sodium thiosulfate Australas J Dermatol, 2008.PMID 18186845
- [17]Lorriaux A, Chaby G, Dhaille F, et al. Nonuraemic calciphylaxis: response to treatment with pamidronate and negative pressure therapy Clin Exp Dermatol, 2015.PMID 25476249
- [18]Bravo-Soto GA, Madrid T Sevelamer versus calcium-based phosphate binders for chronic kidney disease Medwave, 2017.PMID 28525528
- [19]Nikolov IG, Joki N, Maizel J, Lacour B, Drüeke TB, Massy ZA Pleiotropic effects of the non-calcium phosphate binder sevelamer Kidney Int Suppl, 2006.PMID 17136111
- [20]Søndergaard C, Nagarajah S, Shen J, Bladbjerg EM Calciphylaxis in chronic kidney disease: a systematic review of pathomolecular mechanisms and risk factors Ren Fail, 2026.PMID 42572798
- [21]Nigwekar SU, Wolf M, Sterns RH, Hix JK Calciphylaxis from nonuremic causes: a systematic review Clin J Am Soc Nephrol, 2008.PMID 18417747
- [22]Block GA Prevalence and clinical consequences of elevated Ca x P product in hemodialysis patients Clin Nephrol, 2000.PMID 11076108
- [23]Soni S, Leslie WD Bone scan findings in metastatic calcification from calciphylaxis Clin Nucl Med, 2008.PMID 18580243
- [24]Rroji M, Spasovski G Calcimimetics versus parathyroidectomy: What is preferable? Int Urol Nephrol, 2018.PMID 29532306