Severe Symptomatic Hypophosphataemia as a Complication of Parenteral Iron Replacement

Area of Science:

• Endocrinology
• Nephrology
• Hematology

Background:

• Parenteral iron is used for severe iron deficiency or intolerance to oral iron.
• Hypophosphataemia is a potential complication of parenteral iron, possibly linked to carbohydrate moieties.
• Symptoms of hypophosphataemia, like fatigue and weakness, can be mistaken for anemia, leading to underdiagnosis.

Purpose of the Study:

• To report a case of severe hypophosphataemia in a patient receiving parenteral ferric carboxymaltose (FCM).
• To investigate the mechanism of hypophosphataemia in this context.
• To highlight the importance of monitoring phosphate levels during parenteral iron therapy.

Main Methods:

• Case report of a patient with iron deficiency anemia receiving multiple doses of parenteral FCM.
• Evaluation included assessment of renal phosphate wasting and serum fibroblast growth factor 23 (FGF23) levels.
• Treatment involved cessation of FCM and initiation of high-dose oral iron supplementation.

Main Results:

• The patient presented with non-specific symptoms attributed to iron deficiency anemia.
• Severe hypophosphataemia was identified, alongside increased renal phosphate wasting and elevated FGF23.
• Discontinuation of FCM and oral iron supplementation resolved hypophosphataemia without recurrence.

Conclusions:

• The carbohydrate content of parenteral iron preparations may influence hypophosphataemia development in a dose-dependent manner.
• Increased FGF23 levels lead to renal phosphate wasting, explaining the mechanism of hypophosphataemia post-parenteral iron.
• Routine monitoring of serum phosphate levels is recommended for patients receiving parenteral iron, particularly ferric carboxymaltose or iron polymaltose, to detect underdiagnosed hypophosphataemia.