title: A calculation model for serum ionized calcium based on an equilibrium equation for complexation.
abstract: Measurement of ionized calcium is more important than measurement of total calcium in serum samples. In the present study, equations were derived from complexation and acid dissociation equilibrium equations, and were used to determine the concentration of ionized calcium from the observed serum concentrations of total calcium, albumin, total protein, and inorganic phosphate. The ionized calcium concentration was calculated in 67 serum samples from healthy subjects and 34 outpatients previously identified as having abnormal serum calcium levels. The correlation coefficient between our method (y) and the calcium-ion-selective electrode method (x) was 0.953 and the linear regression equation was y = 0.97x at pH 7.4 with a factor of α = 0.21, which was based on the differences between the concentrations of calcium phosphorus compounds obtained by the electrode method and by calculation. The developed calculation is as useful and accurate as the electrode method, and therefore extremely useful for clinical diagnoses.
authors: Faculty of Health Sciences, Kobe University Graduate School of Health Sciences, Kobe, Japan.
authors: Susumu
authors: S
authors: Takano
authors: Hiroshi
authors: H
authors: Kaji
authors: Fujio
authors: F
authors: Hayashi
authors: Kanae
authors: K
authors: Higashiguchi
authors: Sachie
authors: S
authors: Joukei
authors: Yoshiaki
authors: Y
authors: Kido
authors: Juro
authors: J
authors: Takahashi
authors: Kayo
authors: K
authors: Osawa