Ferric carboxymaltose (Ferinject®) associated hypophosphataemia: case report illustrating the need for increased awareness to minimise incidence and risk.

Ferric carboxymaltose (Ferinject®) is an infusion administered for the treatment of iron deficiency anaemia. A number of previous case reports have shown the occurrence of hypophosphataemia after Ferinject® treatment, supposedly managed though high dose phosphate therapy. This case report highlights the risk associated with, and futility of, managing this adverse effect through high dose phosphate infusion. A review of the available literature suggests that if hypophosphataemia develops as a result of Ferinject®, through upregulation of the renal protein Fibroblast Growth Factor-23, it cannot be readily reversed and on average persists for circa 50 days. Acute medical units should be aware of this - likely underreported - adverse effect, and avoid treating these hypophosphataemic patients with high dose phosphate since it can compound symptoms.