title: Association of cumulatively low or high serum calcium levels with mortality in long-term hemodialysis patients.
abstract: BACKGROUND
  The outcome-predictability of baseline and instantaneously changing serum calcium in hemodialysis patients has been examined. We investigated the mortality-predictability of time-averaged calcium values to reflect the 'cumulative' effect of calcium burden over time.
  
  
  METHODS
  We employed a Cox model using up-to-5-year (7/2001-6/2006) time-averaged values to examine the mortality-predictability of cumulative serum calcium levels in 107,200 hemodialysis patients prior to the use of calcimimetics, but during the time where other calcium-lowering interventions, including lower dialysate calcium, were employed.
  
  
  RESULTS
  Both low (<9.0 mg/dl) and high (>10.0 mg/dl) calcium levels were associated with increased mortality (reference: 9.0 to <9.5 mg/dl). Whereas mortality of hypercalcemia was consistent, hypocalcemia mortality was most prominent with higher serum phosphorus (>3.5 mg/dl) and PTH levels (>150 pg/ml). Higher paricalcitol doses shifted the calcium range associated with the greatest survival to the right, i.e. from 9.0 to <9.5 to 9.5 to <10.0 mg/dl. African-Americans exhibited the highest death hazard ratio of hypocalcemia <8.5 mg/dl, being 1.35 (95% CI: 1.22-1.49). Both a rise and drop in serum calcium over 6 months were associated with increased mortality compared to the stable group.
  
  
  CONCLUSIONS
  Whereas in hemodialysis patients cumulatively high or low calcium levels are associated with higher death risk, subtle but meaningful interactions with phosphorus, PTH, paricalcitol dose and race exist.
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90509-2910, USA.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Miller
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.forename: Keith C
authors.initials: KC
authors.lastname: Norris
authors.forename: Rajnish
authors.initials: R
authors.lastname: Mehrotra
authors.forename: Allen R
authors.initials: AR
authors.lastname: Nissenson
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kopple
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D050071:Bone Density Conservation Agents / Q000008:administration & dosage; D002423:Cause of Death; D004872:Ergocalciferols / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000150:complications* / Q000208:ethnology; D006996:Hypocalcemia / Q000150:complications* / Q000208:ethnology; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000208:ethnology / Q000401:mortality*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D013997:Time Factors
chemical_list: D050071:Bone Density Conservation Agents; D004872:Ergocalciferols; D010281:Parathyroid Hormone; C084656:paricalcitol
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