Pitfalls of measuring total blood calcium in patients with CKD.
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.
Gauci
Cédric
C
Département de Physiologie, Hôpital Européen Georges Pompidou, 20-40 rue Leblanc, F-75015 Paris, France.
Moranne
Olivier
O
Fouqueray
Bruno
B
de la Faille
Renaud
R
Maruani
Gérard
G
Haymann
Jean-Philippe
JP
Jacquot
Christian
C
Boffa
Jean-Jacques
JJ
Flamant
Martin
M
Rossert
Jérôme
J
Urena
Pablo
P
Stengel
Bénédicte
B
Souberbielle
Jean-Claude
JC
Froissart
Marc
M
Houillier
Pascal
P
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*
D012709:Serum Albumin; D002118:Calcium