Greater Glasgow and Clyde Medicines

Ferric carboxymaltose (Ferinject®▼) and risk of hypophosphataemia


Key messages

  • A recent MHRA Drug Safety Update highlighted the risk of symptomatic hypophosphataemia leading to osteomalacia and fractures in patients treated with ferric carboxymaltose (Ferinject®).
  • Healthcare professionals are advised to monitor serum phosphate levels in patients requiring multiple high-dose administrations, on long-term treatment, or with pre-existing risk factors for hypophosphataemia. Treatment should be re-evaluated if hypophosphataemia persists.
  • ANY suspected adverse drug reactions (ADRs) should be reported to the Yellow Card Scheme.

Ferric carboxymaltose (Ferinject®) is known to be commonly associated with hypophosphataemia. Symptomatic hypophosphataemia leading to infrequent reports of hypophosphataemic osteomalacia (inadequate mineralisation of the bone matrix leading to softening of the bones) and fractures have been reported in the post-marketing setting. All cases presented in patients with one or more risk factors for osteomalacia and following prolonged exposure to high doses of ferric carboxymaltose (Ferinject®). Some cases required surgical intervention. Based on available data, it is difficult to estimate the magnitude of the risk of hypophosphataemic osteomalacia and therefore the risk of this adverse reaction is included in the product information with a frequency category of not known.

Mechanism and risk with other intravenous irons
The risk of persistent hypophosphataemia and osteomalacia may be higher with ferric carboxymaltose (Ferinject®) than with other intravenous iron formulations. A key mechanism postulated is that the carbohydrate moieties in ferric carboxymaltose (Ferinject®) may disproportionately inhibit degradation of fibroblast growth factor 23 (FGF23), which can result in increased FGF23 activity and ultimately greater renal phosphate wasting.

For further information on IV iron therapy refer to the GGC guideline on the Treatment of Iron Deficiency Anaemia (IDA) available here.

A series of blog articles relating to the treatment of IDA are available:

Updated Guideline - Treatment of IDA
Diagnosis of IDA - Iron Studies
Treatment of IDA – Oral Iron Therapy
Treatment of IDA - IV iron therapy


Published 01/06/21. Link to guideline updated 21/03/2022 and again 05/12/2022.

Medicines update blogs are correct at the time of publication.