Intravenous iron-induced hypophosphataemia (FGF23-mediated mechanism)
Core concept
- Mechanism is FGF23, not PTH
- Certain IV iron carbohydrate moieties -> inc intact FGF23 (by reducing its cleavage into inactive fragments)
- inc FGF23 at the proximal tubule
- dec NaPi-2a / NaPi-2c -> renal phosphate wasting
- dec 1-alpha-hydroxylase and inc 24-hydroxylase -> dec 1,25(OH)2 vitamin D
- -> dec gut phosphate absorption (a second hit)
- -> hypophosphataemia with high urinary phosphate and inappropriately low calcitriol
- Secondary hyperparathyroidism follows (from the low calcitriol) - it is a consequence, not the driver
- A drug-induced phenocopy of tumour-induced osteomalacia / XLH
3 more sections, plus exam facts
Premium unlocks every note across every specialty, and the full exam fact library behind it.
Get premium access