title: The association of vitamin D use with hypercalcemia and hyperphosphatemia in hemodialysis patients: a case-crossover study.
abstract: OBJECTIVE
  Elevated levels of phosphorus (P) and calcium (Ca) have been shown in observational studies to be associated with an increased risk of adverse clinical outcomes including mortality. Vitamin D sterols have been shown to increase the risk of hypercalcemia and hyperphosphatemia in clinical trials. We sought to explore these risks in real-world clinical practice.
  
  
  METHODS
  We employed a case-crossover design, which eliminates confounding by non-time-varying patient characteristics by comparing, within each patient, vitamin D doses before the event with those at an earlier period. Using this method, we estimated the risk of hypercalcemic (Ca ≥ 11 g/dL) and hyperphosphatemic (P ≥ 8 g/dL) events for patients at different dose quartiles of vitamin D relative to patients not on a vitamin D sterol.
  
  
  RESULTS
  There was a dose-dependent association between vitamin D dose quartile and risk of hypercalcemia or hyperphosphatemia. In adjusted analyses, each increase in vitamin D quartile was associated with a multiple of hypercalcemia risk between 1.7 and 19 times compared with those not on vitamin D and a multiple of hyperphosphatemia risk between 1.8 and 4.
  
  
  CONCLUSIONS
  Use of vitamin D sterols is associated with an increased risk of hypercalcemic and hyperphosphatemic events in real-world clinical practice. Other potential predictors of these events, such as phosphate binder use and dialysate Ca levels, were not examined in this analysis.
authors: Amgen, Inc., Thousand Oaks, CA 91320, USA. rkilpatr@amgen.com
authors: Ryan D
authors: RD
authors: Kilpatrick
authors: Mark D
authors: MD
authors: Danese
authors: Vasily
authors: V
authors: Belozeroff
authors: Karen
authors: K
authors: Smirnakis
authors: William G
authors: WG
authors: Goodman
authors: Kenneth J
authors: KJ
authors: Rothman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced*; D054559:Hyperphosphatemia / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D014807:Vitamin D / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D014807:Vitamin D