title: Pitfalls of measuring total blood calcium in patients with CKD.
abstract: Disorders of mineral and bone metabolism are prevalent in patients with chronic kidney disease (CKD). The recent National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend that blood calcium (Ca) be regularly measured in patients with stages 3 to 5 CKD. The Kidney Disease: Improving Global Outcomes (KDIGO) position states that the measurement of ionized Ca (iCa) is preferred and that if total Ca (tCa) concentration is used instead, then it should be adjusted in the setting of hypoalbuminemia. In 691 consecutive patients with stages 3 to 5 CKD, we compared the ability of noncorrected and albumin-corrected tCa concentration to identify low, normal, or high iCa concentration. The agreement between noncorrected or albumin-corrected tCa and iCa was only fair. The risk for underestimating ionized calcium was independently increased by a low total CO(2) concentration when either noncorrected or albumin-corrected Ca was used and by a low albumin concentration only when noncorrected tCa was used. The risk for overestimating iCa was increased by a low albumin concentration only when albumin-corrected Ca was used. In conclusion, albumin-corrected tCa does not predict iCa better than noncorrected tCa. Moreover, both noncorrected and albumin-corrected tCa concentrations poorly predict hypo- or hypercalcemia in patients with CKD.
authors.affiliation: Département de Physiologie, Hôpital Européen Georges Pompidou, 20-40 rue Leblanc, F-75015 Paris, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Gauci
authors.forename: Olivier
authors.initials: O
authors.lastname: Moranne
authors.forename: Bruno
authors.initials: B
authors.lastname: Fouqueray
authors.forename: Renaud
authors.initials: R
authors.lastname: de la Faille
authors.forename: Gérard
authors.initials: G
authors.lastname: Maruani
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Haymann
authors.forename: Christian
authors.initials: C
authors.lastname: Jacquot
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Boffa
authors.forename: Martin
authors.initials: M
authors.lastname: Flamant
authors.forename: Jérôme
authors.initials: J
authors.lastname: Rossert
authors.forename: Pablo
authors.initials: P
authors.lastname: Urena
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Stengel
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Souberbielle
authors.forename: Marc
authors.initials: M
authors.lastname: Froissart
authors.forename: Pascal
authors.initials: P
authors.lastname: Houillier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D051436:Renal Insufficiency, Chronic / Q000097:blood*; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D012709:Serum Albumin; D002118:Calcium