Hypophosphataemia in adults: approach to diagnosis and management

Hypophosphataemia is a common electrolyte disorder which can have clinically significant consequences for bone, muscle, neurological and haematological function. Its causes range from transient transcellular shifts in hospitalised patients to chronic renal phosphate-wasting disorders mediated by fibroblast growth factor 23 (FGF23). A stepwise diagnostic approach enables identification of the underlying aetiology and guides management. While most cases are managed with removal of causative factors and phosphate supplementation, burosumab has revolutionised the treatment of patients with chronic FGF23-mediated hypophosphataemia. This review provides a practical framework for the evaluation and management of hypophosphataemia in adults, with focussed discussion of iron infusion-associated hypophosphataemia, X-linked hypophosphataemia and tumour-induced osteomalacia.