Ionized calcium measurements are influenced by albumin – should ionized calcium be corrected?

References

• Calvi LM, Bushinsky DA. When is it appropriate to order an ionized calcium? J Am Soc Nephrol 2008;19:1257–60.
   PubMed Web of Science ®Google Scholar
• Dickerson RN, Alexander KH, Minard G, Croce MA, Brown RO. Accuracy of methods to estimate ionized and ‘corrected’ serum calcium concentrations in critically ill multiple trauma patients receiving specialized nutrition support. JPEN J Parenter Enteral Nutr 2004;28:133–41.
   PubMedGoogle Scholar
• McLean FC, Hastings AB. A biological method for the estimation of calcium ion concentration. J Biol Chem 1934;170:337–50.
   Google Scholar
• Baird GS. Ionized calcium. Clin Chim Acta 2011;412: 696–701.
   PubMed Web of Science ®Google Scholar
• Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. Br Med J 1973;4:643–6.
   PubMed Web of Science ®Google Scholar
• Orrell DH. Albumin as an aid to the interpretation of serum calcium. Clin Chim Acta 1971;35:483–9.
   PubMed Web of Science ®Google Scholar
• McLean FC. Construction of a cartesian nomogram for the law of mass action. Science 1935;82:104–5.
   PubMedGoogle Scholar
• Ross JW. Calcium-selective electrode with liquid ion exchanger. Science 1967;156:1378–9.
   PubMed Web of Science ®Google Scholar
• Conceicao SC, Weightman D, Smith PA, Luno J, Ward MK, Kerr DN. Serum ionised calcium concentration: measurement versus calculation. Br Med J 1978;1:1103–5.
   PubMed Web of Science ®Google Scholar
• Larsson L, Ohman S. Serum ionized calcium and corrected total calcium in borderline hyperparathyroidism. Clin Chem 1978;24:1962–5.
   PubMed Web of Science ®Google Scholar
• Thode J, Juul-Jorgensen B, Bhatia HM, Kjaerulf-Nielsen M, Bartels PD, Fogh-Andersen N, Siggaard-Andersen O. [Ionized calcium, total calcium and albumin corrected calcium in the serum in 1213 patients with suspected calcium metabolic diseases. A prospective multicenter study]. Ugeskr Laeger 1989;151:2423–5.
   PubMedGoogle Scholar
• Zaloga GP, Chernow B, Cook D, Snyder R, Clapper M, O’Brian JT. Assessment of calcium homeostasis in the critically ill surgical patient. The diagnostic pitfalls of the McLean-Hastings nomogram. Ann Surg 1985;202:587–94.
   PubMed Web of Science ®Google Scholar
• Ferreira P, Bold AM. Clinical laboratory evaluation of the Orion SS-20 ionized calcium analyser. J Automat Chem 1979;1:94–102.
   PubMedGoogle Scholar
• Fogh-Andersen N. Ionized calcium analyzer with a built- in pH correction. Clin Chem 1981;27:1264–7.
   PubMed Web of Science ®Google Scholar
• Larsson L, Ohman S. Effect of silicone-separator tubes and storage time on ionized calcium in serum. Clin Chem 1985;31:169–70.
   PubMed Web of Science ®Google Scholar
• Gouget B, Gourmelin Y, Blanchet F, Truchaud A. A reliable potentiometric measurement of ionized calcium and pH on the ICA2 Radiometer in clinical practice. Scand J Clin Lab Invest 1989;49:345–9.
   PubMed Web of Science ®Google Scholar
• Payne RB. An isotonic potassium chloride liquid junction minimises the effects of ionic strength, protein and haematocrit on ionised calcium measurement. Ann Clin Biochem 1988;25(Pt 3):228–32.
   PubMed Web of Science ®Google Scholar
• Butler SJ, Payne RB, Gunn IR, Burns J, Paterson CR. Correlation between serum ionised calcium and serum albumin concentrations in two hospital populations. Br Med J (Clin Res Ed) 1984;289:948–50.
   PubMed Web of Science ®Google Scholar
• Freaney R, Egan T, McKenna MJ, Doolin MC, Muldowney FP. Determination of ionised calcium by ion selective electrode is not independent of albumin concentration. Clin Chim Acta 1986;158:129–37.
   PubMed Web of Science ®Google Scholar
• Masters PW, Payne RB. Comparison of hypertonic and isotonic reference electrode junctions for measuring ionized calcium in whole blood: a clinical study. Clin Chem 1993;39:1082–5.
   PubMed Web of Science ®Google Scholar
• McEnroe E, McKenna MJ, Diamond D, Covington AK, Freaney R. Dependence of measured ionized calcium on protein concentration as measured by three ion-selective electrodes. Ann Clin Biochem 1992;29(Pt 4):443–9.
   PubMed Web of Science ®Google Scholar
• Payne RB. Clinically significant effect of protein concentration on ion-selective electrode measurements of ionised calcium. Ann Clin Biochem 1982;19(Pt 4):233–7.
   PubMed Web of Science ®Google Scholar
• Payne RB, Jones DP. Protein interferes with ionised calcium measurement at the reference electrode liquid junction. Ann Clin Biochem 1987;24(Pt 4):400–7.
   PubMed Web of Science ®Google Scholar
• Saris NE. Protein does not interfere with the ion- selective electrode determination of calcium, sodium or potassium ions. J Clin Chem Clin Biochem 1988; 26:101–4.
   PubMedGoogle Scholar
• Thode J, Boyd JC, Ladenson JH. Activity measurements of calcium, sodium, potassium, and chloride after equilibrium dialysis used to show lack of evidence for protein interference with calcium electrodes. Clin Chem 1987; 33:1811–3.
   PubMed Web of Science ®Google Scholar
• Thode J, Fogh-Andersen N, Siggaard-Andersen M, Siggaard-Andersen O. Donnan effect or protein interference in ionised calcium measurements? Ann Clin Biochem 1983;20(Pt 5):271–3.
   PubMed Web of Science ®Google Scholar
• Payne RB, Buckley BM, Rawson KM. Protein interference with ion-selective electrode measurement depends on reference electrode composition and design. Ann Clin Biochem 1991;28(Pt 1):68–72.
   PubMed Web of Science ®Google Scholar
• Lindgarde F. Potentiometric determination of serum ionized calcium in a normal human population. Clin Chim Acta 1972;40:477–84.
   PubMed Web of Science ®Google Scholar
• Ladenson JH, Lewis JW, Boyd JC. Failure of total calcium corrected for protein, albumin, and pH to correctly assess free calcium status. J Clin Endocrinol Metab 1978;46:986–93.
   PubMed Web of Science ®Google Scholar
• Pain RW, Rowland KM, Phillips PJ, Duncan BM. Current ‘corrected’ calcium concept challenged. Br Med J 1975; 4:617–9.
   PubMed Web of Science ®Google Scholar
• Thode J, Fogh-Andersen N, Wimberley PD, Moller SA, Siggaard-Andersen O. Relation between pH and ionized calcium in vitro and in vivo in man. Scand J Clin Lab Invest 1983;165(Suppl.):79–82.
   Google Scholar