An analysis of measured and calculated calcium quantities in serum.
Potentiometrically measured ionized calcium (Ca2+) was compared with total and albumin corrected S-Calcium and calculated Ca2+ in serum samples from blood donors and patients, for whom a request of S-Calcium has been made. Total S-Calcium, Ca2+ and S-Albumin in donors conformed with a simple mass law equation with a mean KCaAlb = 95 l/mol, whereas apparent albumin binding affinity rose with decreasing S-Albumin in patients (due to rise of other calcium binding proteins) with resulting overestimation of albumin corrected and particularly of calculated Ca2+. The frequency and severity of hypoalbuminaemia in patients make calculated Ca2+ unreliable and albumin corrected S-Calcium the clinically most satisfactory routinely practicable substitute for direct Ca2+ measurement.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008297:Male; D008722:Methods; D008875:Middle Aged; D011485:Protein Binding; D012044:Regression Analysis; D012709:Serum Albumin / Q000032:analysis; D012737:Sex Factors
D007477:Ions; D012709:Serum Albumin; D002118:Calcium