Hypercalcaemia and Hyperparathyroidism — SAQ

Stem

A 68-year-old woman is brought to the emergency department by her family with three days of progressive confusion, constipation, nausea and polyuria. She has a past history of recurrent calcium oxalate renal stones and a fragility fracture of the distal radius two years ago. She takes no prescribed drugs. On examination she is dehydrated, GCS 13 (E4 V4 M5), BP 96/60, pulse 110/min. ECG shows a QTc of 360 ms. Bloods: corrected calcium 3.7 mmol/L (14.8 mg/dL), phosphate 0.6 mmol/L (low), ALP 220 U/L, creatinine 165 micromol/L (baseline 80), intact PTH 12.4 pmol/L (reference 1.6 to 6.9), 25-OH-D 78 nmol/L.^[1]

Questions

a) What is the diagnosis and what two biochemical features best support it? (2 marks)

Diagnosis: symptomatic severe hypercalcaemia / hypercalcaemic crisis secondary to primary hyperparathyroidism (likely a parathyroid adenoma). Two supportive features: (1) markedly elevated intact PTH (12.4 pmol/L) in the face of severe hypercalcaemia (3.7 mmol/L) — PTH should be suppressed by this calcium; an inappropriately normal or high PTH defines PTH-dependent disease; (2) hypophosphataemia (PTH/PTHrP phosphaturic effect).^[1]

b) Outline the immediate (resuscitation) management over the first 24 hours, naming specific drugs with doses and rationale. (4 marks)

• ABCDE + IV access + cardiac monitoring (shortened QT, arrhythmia risk).^[1][4]
• Aggressive isotonic saline 3 to 6 L over 24 h (start 200 to 500 mL/h titrated to euvolaemia and urine output) — restores intravascular volume,^[4] glomerular filtration and calciuria; the patient is volume-depleted from polyuria and vomiting.
• IV bisphosphonate: zoledronate 4 mg over 15 min or pamidronate 60 to 90 mg over 2 to 4 h — osteoclast inhibition; onset 24 to 48 h, nadir 4 to 7 days, lasts weeks. (Dose-adjust for creatinine 165 — pamidronate preferred; check renal function.)^[1][4]
• Calcitonin 4 to 8 IU/kg SC every 12 h — fastest onset (4 to 6 h) as a bridge to bisphosphonate effect; tachyphylaxis at 48 h.^[3]
• Stop any thiazides, lithium, vitamin D, calcium supplements (none here).^[1][4]
• Search for and treat the cause in parallel — sestamibi + neck ultrasound once stabilised.^[1]

c) What is the definitive management and what clinical/laboratory criteria would justify it? (3 marks)

Definitive: parathyroidectomy (curative, success over 95 percent with intraoperative PTH).^[1] This patient meets multiple surgical criteria from the international workshop framework (as enumerated in the 2024 Italian AME/SIOMMMS guideline): symptomatic disease (recurrent stones, fragility fracture, hypercalcaemic crisis), calcium markedly over the upper limit of normal, fragility fracture (skeletal criterion), renal stones (renal criterion), and eGFR under 60 (renal criterion). Localise the adenoma preoperatively with sestamibi SPECT/CT and high-resolution neck ultrasound; perform focused minimally invasive parathyroidectomy with intraoperative PTH (intraoperative PTH fall criterion — surgical convention).

d) What serious post-operative complication must you anticipate over the next 48 to 72 hours, and how would you manage it? (1 mark)

Hungry bone syndrome — severe prolonged hypocalcaemia, hypophosphataemia, hypokalaemia and hypomagnesaemia due to sudden bone remineralisation after parathyroidectomy. Risk is high given long-standing severe disease with high ALP. Manage with serial calcium, phosphate, magnesium, potassium monitoring, high-dose oral calcium + IV calcium gluconate if severe, oral calcitriol 0.5 to 1 microgram daily, and magnesium/potassium replacement, often for days to weeks.^[1][4]

References4ShowHide

1. [1]Turner JJO. Hypercalcaemia - presentation and management Clin Med (Lond), 2017.PMID 28572230
2. [2]Major PP, Coleman RE. Zoledronic acid in the treatment of hypercalcemia of malignancy: results of the international clinical development program Semin Oncol, 2001.PMID 11346861
3. [3]Nussbaum SR. Pathophysiology and management of severe hypercalcemia Endocrinol Metab Clin North Am, 1993.PMID 8325291
4. [4]Davidson TG. Conventional treatment of hypercalcemia of malignancy Am J Health Syst Pharm, 2001.PMID 11757206