Paeds · endocrinology-diabetes-and-growth
Rickets and metabolic bone disease
Also known as nutritional rickets · vitamin D deficiency rickets · hypocalcaemic rickets · X-linked hypophosphataemia · vitamin D-dependent rickets
A fellowship approach to rickets and metabolic bone disease in children: defective mineralisation of growing bone that is almost always preventable, the calcipenic-versus-phosphopenic classification that the biochemistry reveals in seconds, the vitamin D cascade and where it breaks, the symptomatic hypocalcaemic infant who needs intravenous calcium before vitamin D, and the lifelong pathway for hereditary forms such as X-linked hypophosphataemia.
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- A hypocalcaemic infant presenting with seizure, stridor, or tetany is an emergency — give intravenous calcium gluconate first, then oral calcium with cholecalciferol; never vitamin D alone, which can deepen hypocalcaemia through hungry bone
- A low alkaline phosphatase in a child who looks rachitic is hypophosphatasia, not nutritional rickets — bisphosphonates are harmful and the treatment is enzyme replacement
- Exclusive breastfeeding without vitamin D supplementation is the commonest single cause of nutritional rickets in high-income countries — the 400 IU daily supplement is non-negotiable from soon after birth
- Dark skin, high latitude, concealing clothing, and maternal vitamin D deficiency stack the risk; a breastfed infant of a veiled or dark-skinned mother in a temperate climate is the textbook presentation
- Normal 25-hydroxyvitamin D does not exclude rickets — calcium-deficiency rickets and X-linked hypophosphataemia both produce rickets with a normal vitamin D level, so read the calcium, phosphate, and PTH first
- Persistent hypophosphataemia with rachitic changes and normal PTH points to FGF23-mediated disease such as X-linked hypophosphataemia; giving vitamin D alone will not heal it and the child needs calcitriol with phosphate
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Board mappings
- General and Community Paediatrics
- Endocrinology and diabetes
- Growth and Development
- Endocrinology - recognise, investigate and manage calcium, phosphate and bone disorders including rickets
- General and community paediatrics - recognise the role of vitamin D supplementation and nutrition in prevention
- Renewed curriculum for first-year trainees from 2027 - Learning goal 6: Clinical management - essential general paediatrics
- Endocrinology 10-12
- Metabolic bone disease 10-12
- Clinical Applications
- Long Cases
- Short Cases
- 5. Endocrinology and growth - disorders of calcium, phosphate and bone (rickets)
- 1. Neonates and infants with endocrinology and nutrition
- 4. Professional skills and knowledge: Patient management
- Foundation of Practice (FOP)
- Theory and Science (TAS)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
- Communication
- Video
- General Pediatrics Content Outline - D22 Endocrinology (4%)
- General Pediatrics Content Outline - D21 Nutrition (3%)
- General Pediatrics Content Outline - Universal Task 4: Management and Treatment
- Patient Care 4: Clinical Reasoning
- Patient Care 5: Patient Management
- Medical Knowledge 1: Congenital anomalies and genetics
- Systems-Based Practice 1: Patient Safety
- Medical Expert
- Pediatrics: Foundations EPA #8 - Communicating assessment findings and management plans to patients and/or families
- Pediatrics: Endocrinology and nutrition applied domain
Picture the child who walks in. A toddler is brought in because the legs have bowed since she started walking, the wrists look thick, and the fontanelle is still open at eighteen months. Or a six-month-old, exclusively breastfed by a veiled mother in a southern winter, is brought to the emergency department fitting, with a calcium of 1.4 and a cholecalciferol level that is unmeasurable. Or a school-age child with short stature and repeated dental abscesses turns out to have X-linked hypophosphataemia that was never nutritional at all. The fellowship task in each is to read the calcium, phosphate, and parathyroid hormone before the vitamin D level, and to treat the cause rather than reflexively loading vitamin D. [8] [9]
Order the bloods as Calcium, then Alkaline phosphatase, then Phosphate, then Parathyroid hormone, and only then the 25-hydroxyvitamin D. The first four tell you whether the rickets is calcipenic or phosphopenic before you know the vitamin D status, and they redirect the entire work-up. A low calcium with high parathyroid hormone is calcipenic; a low phosphate with normal parathyroid hormone is phosphopenic. Reach for the vitamin D level last, because a normal vitamin D never excludes rickets. [1] [5]
Overview & Definition
Rickets is the failure of mineralisation at the growing cartilage of the epiphyseal plate, and the companion lesion in bone already formed is osteomalacia, the failure of mineralisation of osteoid. In a growing child the two coexist, and the clinical and radiographic picture reflects both: the softened growth plate widens and bows under load, while the unmineralised osteoid accumulates and deforms. The unifying problem is a mineral shortfall at the mineralisation front, and that shortfall is driven by a deficiency of calcium, of phosphate, or of the vitamin D that delivers calcium to the gut. [5] [7]
The historical weight of the disease is large. Before supplementation and fortification, nutritional rickets was among the commonest causes of disability in children, and its disappearance from high-income populations in the twentieth century was one of public health's clearest victories. Its return in the twenty-first century, in exclusively breastfed infants, in dark-skinned and veiled populations at high latitude, and in refugee and migrant families, is documented across Europe, North America, and Australasia, and it is the reason every general paediatrician must still own the topic. [8] [6]
What makes rickets a fellowship-level subject rather than a single-disease memory is that the mineralisation failure has many causes that look identical on a radiograph and nearly identical on examination, yet demand completely different treatment. Nutritional vitamin D deficiency is the commonest and the most preventable, but calcium deficiency, genetic defects of vitamin D metabolism (vitamin D-dependent rickets), and renal phosphate wasting (X-linked hypophosphataemia) all produce the same widened, frayed metaphysis. Distinguishing them is a biochemical exercise, and the biochemistry is read in seconds once you know the cascade. [5] [1]
References12ShowHide
- [1]Munns CF, Shaw N, Kiely M, et al. Global Consensus Recommendations on Prevention and Management of Nutritional Rickets. J Clin Endocrinol Metab, 2016.PMID 26745253
- [2]Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 2011.PMID 21646368
- [3]Wagner CL, Greer FR Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics, 2008.PMID 18977996
- [4]Abrams SA Calcium and vitamin d requirements of enterally fed preterm infants. Pediatrics, 2013.PMID 23629620
- [5]Carpenter TO, Shaw NJ, Portale AA, et al. Rickets. Nat Rev Dis Primers, 2017.PMID 29265106
- [6]Creo AL, Thacher TD, Pettifor JM, et al. Nutritional rickets around the world: an update. Paediatr Int Child Health, 2017.PMID 27922335
- [7]Prentice A. Nutritional rickets around the world. J Steroid Biochem Mol Biol, 2013.PMID 23220549
- [8]Ahmed SF, Franey C, McDevitt H, et al. Recent trends and clinical features of childhood vitamin D deficiency presenting to a children's hospital in Glasgow. Arch Dis Child, 2011.PMID 20584848
- [9]Kamenický P, Briot K, Munns CF, et al. X-linked hypophosphataemia. Lancet, 2024.PMID 39181153
- [10]Mornet E. Hypophosphatasia. Orphanet J Rare Dis, 2007.PMID 17916236
- [11]Thacher TD Calcium-deficiency rickets. Endocr Dev, 2003.PMID 12964429
- [12]Fischer PR, Johnson CR, Leopold KN, et al. Treatment of vitamin D deficiency in children. Expert Rev Endocrinol Metab, 2023.PMID 37861060