Detlie TE^1,2, Lindstrøm JC^2,3, Jahnsen ME¹, Finnes E⁴, Zoller H⁵, Moum B^2,4, Jahnsen J^1,2. Aliment Pharmacol Ther. 2019 Jul 2. doi: 10.1111/apt.15386. [Epub ahead of print]

Author information

1 Department of Gastroenterology, Akershus University Hospital, Lørenskog, Norway.

2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway.

3 Health Services Research Unit, Akershus University Hospital, Lørenskog, Norway.

4 Division of Medicine, Department of Gastroenterology, Oslo University Hospital Ullevål, Oslo, Norway.

5 Department of Medicine II, Gastroenterology and Hepatology, Medical University of Innsbruck, Innsbruck, Austria.

Abstract

BACKGROUND: Iron deficiency and iron deficiency anaemia are common complications in inflammatory bowel disease (IBD). In patients with moderate-to-severe anaemia, oral iron intolerance or ineffectiveness of oral iron, ferric carboxymaltose and ironisomaltoside are widely used. Hypophosphatemia is a side effect of both preparations.

AIMS: To investigate the occurrence of hypophosphatemia in IBD patients with iron deficiency/iron deficiency anaemia treated with high-dose intravenous iron.

METHODS: A prospective observational study of adult IBD patients with iron deficiency/iron deficiency anaemia was conducted at two study sites where patients received 1000 mg of ferric carboxymaltose or iron isomaltoside. At baseline, weeks 2 and 6, blood and faecal samples were collected. The primary endpoint was to determine the incidence of moderate-to-severe hypophosphatemia. Secondary endpoints included the total incidence of hypophosphatemia, possible risk factors for hypophosphatemia, and response to single-dose intravenous iron.

RESULTS: One hundred and thirty patients were included. In the per-protocol set, 52 patients received ferric carboxymaltose and 54 patients received iron isomaltoside. Ferric carboxymaltose treatment had a significantly higher incidence of moderate-to-severe hypophosphatemia compared with iron isomaltoside at week 2 (56.9% vs 5.7%, P < 0.001) and a higher incidence at week 6 (13.7% vs 1.9%, P = 0.054).The overall incidence of hypophosphatemia was significantly higher with ferric carboxymaltose compared with iron isomaltoside treatment at weeks 2 (72.5% vs 11.3%, P < 0.001) and 6 (21.6% vs 3.7%, P = 0.013).

CONCLUSIONS: In IBD patients with iron deficiency/iron deficiency anaemia, ferric carboxymaltose was associated with higher incidence, severity and persistence of hypophosphatemia compared with iron isomaltoside. The presence of moderate-to-severe hypophosphatemia beyond 6 weeks is a clinical concern that requires further investigation.