Iron Infusions and Increased Bone Fracture Risk: New Study Findings

Research indicates that the use of ferric carboxymaltose (FCM), an intravenous iron formulation, is associated with an increased risk of bone fractures and osteomalacia in patients treating iron deficiency.

Findings from a study published in the journal Blood and reported on April 7, 2026, suggest that the specific formulation of intravenous iron used can significantly influence bone health outcomes.

Study Design and Patient Analysis

The research was conducted by Austrian researchers who assessed the fracture rates and the occurrence of osteomalacia in a group of 357 patients. The study specifically compared the effects of two different intravenous iron formulations: ferric carboxymaltose (FCM) and ferric derisomaltose (FDI).

The investigators aimed to determine why different formulations of IV iron produced varying effects on mineral metabolism and the subsequent risk of bone fragility.

Comparison of FCM and FDI

The study found that repeated infusions of ferric carboxymaltose were linked to the development of osteomalacia and an increased risk of fractures. In contrast, ferric derisomaltose was found to rarely cause hypophosphatemia, a condition involving low phosphate levels in the blood that is often linked to bone weakening.

The researchers noted that the choice of iron preparation is a critical factor in managing iron deficiency, as the different formulations do not appear to have the same impact on the skeletal system.

Mechanisms of Bone Impairment

The investigators suggested that ferric carboxymaltose may be further impairing already reduced bone formation in patients with iron deficiency. This impairment of the bone-building process contributes to the overall increase in fracture risk.

The study investigated the underlying mechanisms of bone and mineral metabolism to explain why FCM increases fracture risk while FDI does not. A primary point of distinction identified was the effect on phosphate levels, as the reduction of these minerals is essential for maintaining bone density and strength.

Osteomalacia, a softening of the bones that occurs when the bone matrix is not sufficiently mineralized, was increasingly recognized following the repeated administration of FCM infusions.