Prolonged and Refractory Hypophosphataemia Following Intravenous Ferric Carboxymaltose Administration Delaying Hospital Discharge: A Case Report

Hypophosphataemia is an under-recognised complication of intravenous ferric carboxymaltose (Ferinject). While often transient and asymptomatic, in some cases, it may be severe and prolonged. We describe a man in his 40s with iron deficiency anaemia who received two 1,000 mg doses of ferric carboxymaltose within one week. Despite normal baseline renal function and calcium, and only borderline vitamin D insufficiency, he developed profound hypophosphataemia with a nadir of 0.20 mmol/L. This required repeated intravenous phosphate replacement and delayed hospital discharge by eight days, despite the patient being otherwise medically fit. The case underscores that ferric carboxymaltose can cause clinically important hypophosphataemia, even in younger patients, and that routine monitoring should be considered.