An Unusually Prolonged Case of FGF23-mediated Hypophosphatemia Secondary to Ferric Carboxymaltose Use.

Ferric carboxymaltose (FCM)-induced hypophosphatemia is seen in up to 75% of patients receiving this therapy for iron deficiency anemia. Hypophosphatemia has been attributed to increased circulating levels of fibroblast growth factor-23 (FGF23), the transcription of which is upregulated in an iron-deficient state. However, hypophosphatemia typically resolves within 12 weeks of FCM administration.