title: Incidence and aetiology of renal phosphate loss in patients with hypophosphatemia in the intensive care unit.
abstract: BACKGROUND
  Hypophosphatemia is a common finding in patients in the intensive care unit (ICU). Its cause is often poorly understood.
  
  
  OBJECTIVE
  The aim of this study was to understand the incidence of renal phosphate loss in ICU-related hypophosphatemia, and to examine the role of phosphaturic hormones in its etiology.
  
  
  METHODS
  Plasma phosphate levels were measured on day 1, 3, 5 and 7 in 290 consecutive patients admitted to the ICU. Renal phosphate handling and phosphaturic hormones were studied in a subset of patients with phosphate levels <0.6 mmol/L. Renal phosphate loss was defined as a TmP/gfr < 0.6 mmol/L.
  
  
  RESULTS
  Hypophosphatemia developed in 24% of all patients. This mainly occurred within the first 3 days of stay and in patients with serum creatinine levels <150 μmol/L. Renal phosphate loss was present in 80% of patients who developed hypophosphatemia, and was not related to serum levels of parathyroid hormone (PTH), PTH-related protein (PTH-rp), fibroblast growth factor 23 (FGF-23), or calcitonin.
  
  
  CONCLUSIONS
  Hypophosphatemia in the ICU is commonly associated with renal phosphate loss. It mainly occurs within the first 3 days of admission, in particular in patients with preserved renal function. Renal phosphate loss is not explained by elevated PTH, PTH-rp, FGF-23 or calcitonin levels.
authors.affiliation: Department of Internal Medicine, Rijnstate Hospital, Wagnerlaan 55, 6800 TA, Arnhem, The Netherlands, annekebech@hotmail.com.
authors.forename: Anneke
authors.initials: A
authors.lastname: Bech
authors.forename: Michiel
authors.initials: M
authors.lastname: Blans
authors.forename: Darryl
authors.initials: D
authors.lastname: Telting
authors.forename: Hans
authors.initials: H
authors.lastname: de Boer
mesh_terms: D018806:APACHE; D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000502:physiology; D006784:Hospitals, Teaching; D006801:Humans; D017674:Hypophosphatemia / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D015994:Incidence; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007668:Kidney / Q000737:chemistry* / Q000503:physiopathology; D007674:Kidney Diseases / Q000097:blood / Q000209:etiology* / Q000652:urine; D008297:Male; D009426:Netherlands; D010710:Phosphates / Q000097:blood* / Q000502:physiology / Q000652:urine; D011445:Prospective Payment System; D012044:Regression Analysis; D018709:Statistics, Nonparametric
chemical_list: C000717427:FGF23 protein, human; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002097:C-Reactive Protein