title: Choice of High-Dose Intravenous Iron Preparation Determines Hypophosphatemia Risk.
abstract: BACKGROUND
  Ferric carboxymaltose (FCM) and iron isomaltoside 1000 (IIM) are increasingly used because they allow correction of severe iron deficiency in a single infusion. A transient decrease in serum phosphate concentrations is a frequent side effect of FCM.
  
  
  OBJECTIVE
  To characterize this adverse event and search for its predictors in a gastroenterology clinic patient cohort.
  
  
  METHODS
  Electronic medical records of patients attending the University Hospital of Innsbruck were searched for the keywords ferric carboxymaltose or iron isomaltoside. Eighty-one patients with documented administration of FCM or IIM with plasma phosphate concentrations before and after treatment were included.
  
  
  RESULTS
  The prevalence of hypophosphatemia (<0.8 mmol/L) increased from 11% to 32.1% after treatment with i.v. iron. The hypophosphatemia risk was greater after FCM (45.5%) compared with IIM (4%). Severe hypophosphatemia (<0.6 mmol/L) occurred exclusively after FCM (32.7%). The odds for hypophosphatemia after i.v. iron treatment were independently determined by baseline phosphate and the choice of i.v. iron preparation (FCM vs. IIM-OR = 20.8; 95% CI, 2.6-166; p = 0.004). The median time with hypophosphatemia was 41 days, but prolonged hypophosphatemia of ≥ 2 months was documented in 13 of 17 patients in whom follow-up was available. A significant increase in the phosphaturic hormone intact FGF-23 in hypophosphatemic patients shows that this adverse event is caused by FCM-induced hormone dysregulation.
  
  
  CONCLUSIONS
  Treatment with FCM is associated with a high risk of developing severe and prolonged hypophosphatemia and should therefore be monitored. Hypophosphatemia risk appears to be substantially lower with IIM.
authors.affiliation: Medical University of Innsbruck, Department of Medicine II, Gastroenterology and Hepatology, Anichstr. Innsbruck, Austria.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Schaefer
authors.affiliation: Central Institute for Medical and Chemical Laboratory Diagnosis, Innsbruck University Hospital, Anichstr. Innsbruck, Austria.
authors.forename: Philipp
authors.initials: P
authors.lastname: Würtinger
authors.affiliation: Medical University of Innsbruck, Department of Medicine II, Gastroenterology and Hepatology, Anichstr. Innsbruck, Austria.
authors.forename: Armin
authors.initials: A
authors.lastname: Finkenstedt
authors.affiliation: Medical Research Council (MRC) Human Nutrition Research, Elsie Widdowson Laboratories, Fulbourn Road, Cambridge, United Kingdom.
authors.forename: Vickie
authors.initials: V
authors.lastname: Braithwaite
authors.affiliation: Medical University of Innsbruck, Department of Medicine II, Gastroenterology and Hepatology, Anichstr. Innsbruck, Austria.
authors.forename: André
authors.initials: A
authors.lastname: Viveiros
authors.affiliation: Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Endocrinology and Metabolism, Anichstr. Innsbruck, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Effenberger
authors.affiliation: Medical University of Vienna, Department of Pathology, Währingergürtel, Vienna, Austria.
authors.forename: Irene
authors.initials: I
authors.lastname: Sulzbacher
authors.affiliation: Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Endocrinology and Metabolism, Anichstr. Innsbruck, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Moschen
authors.affiliation: Central Institute for Medical and Chemical Laboratory Diagnosis, Innsbruck University Hospital, Anichstr. Innsbruck, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Griesmacher
authors.affiliation: Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Endocrinology and Metabolism, Anichstr. Innsbruck, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Tilg
authors.affiliation: Medical University of Innsbruck, Department of Medicine II, Gastroenterology and Hepatology, Anichstr. Innsbruck, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Vogel
authors.affiliation: Medical University of Innsbruck, Department of Medicine II, Gastroenterology and Hepatology, Anichstr. Innsbruck, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Zoller
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000368:Aged; D018798:Anemia, Iron-Deficiency / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology; D015415:Biomarkers; D004187:Disaccharides / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D005290:Ferric Compounds / Q000008:administration & dosage / Q000009:adverse effects*; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D017674:Hypophosphatemia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008320:Maltose / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D008875:Middle Aged; D010710:Phosphates / Q000097:blood; D015995:Prevalence; D012189:Retrospective Studies; D012306:Risk
chemical_list: D015415:Biomarkers; D004187:Disaccharides; C000717427:FGF23 protein, human; D005290:Ferric Compounds; D010710:Phosphates; C557707:iron isomaltoside 1000; C522335:ferric carboxymaltose; D008320:Maltose; D000089703:Fibroblast Growth Factor-23