title: Ionized calcium concentration and outcome in critical illness.
abstract: OBJECTIVE
  To assess the association of abnormalities of ionized calcium levels with mortality in a heterogeneous cohort of critically ill patients.
  
  
  METHODS
  Retrospective, combined clinical and biochemical study.
  
  
  METHODS
  Four combined medical/surgical intensive care units.
  
  
  METHODS
  Cohort of 7,024 adult critically ill patients.
  
  
  METHODS
  None.
  
  
  RESULTS
  We studied 177,578 ionized calcium measurements, from 7024 patients, with a mean value of 1.11 mmol/L (ionized calcium measured every 4.5 hrs on average). The unadjusted lowest and highest ionized calcium reported during intensive care unit stay were significantly different between intensive care unit survivors and nonsurvivors (p < .001). If hypocalcemia occurred at least once during the intensive care unit stay, the probability of intensive care unit mortality increased by 46%, 108%, and 150% for ionized calcium levels <1.15, 0.90, and 0.80 mmol/L, respectively. If hypercalcemia occurred at least once during the intensive care unit stay, the probability of intensive care unit mortality increased by 100%, 162%, and 190% for ionized calcium levels >1.25, 1.35, and 1.45 mmol/L, respectively. Similar trends were seen for hospital mortality. However, from multivariate logistic regression analysis, only an ionized calcium <0.8 mmol/L or an ionized calcium >1.4 mmol/L were independently associated with intensive care unit and hospital mortality.
  
  
  CONCLUSIONS
  Within a broad range of values, ionized calcium concentration has no independent association with hospital or intensive care unit mortality. Only extreme abnormalities of ionized calcium concentrations are independent predictors of mortality.
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Hospital, Okayama, Japan.
authors.forename: Moritoki
authors.initials: M
authors.lastname: Egi
authors.forename: Inbyung
authors.initials: I
authors.lastname: Kim
authors.forename: Alistair
authors.initials: A
authors.lastname: Nichol
authors.forename: Edward
authors.initials: E
authors.lastname: Stachowski
authors.forename: Craig J
authors.initials: CJ
authors.lastname: French
authors.forename: Graeme K
authors.initials: GK
authors.lastname: Hart
authors.forename: Colin
authors.initials: C
authors.lastname: Hegarty
authors.forename: Michael
authors.initials: M
authors.lastname: Bailey
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis; D002118:Calcium / Q000097:blood*; D020013:Calcium Signaling; D016009:Chi-Square Distribution; D015331:Cohort Studies; D016001:Confidence Intervals; D003422:Critical Care / Q000379:methods; D016638:Critical Illness / Q000401:mortality*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006934:Hypercalcemia / Q000097:blood* / Q000401:mortality* / Q000517:prevention & control; D006996:Hypocalcemia / Q000097:blood* / Q000401:mortality* / Q000517:prevention & control; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016019:Survival Analysis
chemical_list: D015415:Biomarkers; D002118:Calcium