title: Albumin-adjusted calcium is not suitable for diagnosis of hyper- and hypocalcemia in the critically ill.
abstract: OBJECTIVE
  To evaluate whether calcium adjusted for albumin can be used to monitor calcium homeostasis in critically ill patients.
  
  
  METHODS
  Prospective single-single center observational study.
  
  
  METHODS
  Clinical laboratory and critical care unit of a regional teaching hospital.
  
  
  METHODS
  Fifty-three paired samples were from 36 patients requiring intensive care treatment.
  
  
  METHODS
  None.
  
  
  RESULTS
  Total calcium, albumin-adjusted calcium, and ionized calcium were measured in critically ill patients during an 8-wk period. Calcium was adjusted for albumin using the formula that is most frequently used in The Netherlands. Using ionized calcium as the gold standard, albumin-adjusted calcium overestimated hypercalcemia and totally missed hypocalcemia. The same seemed to be true for other formulas used for albumin or protein adjustment of calcium concentrations.
  
  
  CONCLUSIONS
  Albumin-adjusted calcium cannot be used in an intensive care setting to monitor reliably the calcium levels in critically ill patients and should be replaced by measurement of ionized calcium.
authors.affiliation: Department of Clinical Chemistry, Stichting Klinisch Chemisch Laboratorium, Leeuwarden, The Netherlands.
authors.forename: Jennichjen
authors.initials: J
authors.lastname: Slomp
authors.forename: Peter H J
authors.initials: PH
authors.lastname: van der Voort
authors.forename: Rik Th
authors.initials: RT
authors.lastname: Gerritsen
authors.forename: Jan A M
authors.initials: JA
authors.lastname: Berk
authors.forename: Andries J
authors.initials: AJ
authors.lastname: Bakker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D001784:Blood Gas Analysis; D002118:Calcium / Q000097:blood*; D016638:Critical Illness; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006706:Homeostasis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006934:Hypercalcemia / Q000097:blood*; D006996:Hypocalcemia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods* / Q000592:standards; D009426:Netherlands; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000032:analysis*
chemical_list: D012709:Serum Albumin; D002118:Calcium