Determination of biliary ionized Ca²⁺ concentration and its aspect in human gallbladder bile

Abstract

We analyzed total and ionized calcium in pathological human bile in association with biliary lipids. Ca²⁺ concentration was directly determined using conventional Ca²⁺ selective ion meter and a new type of sample container. The accuracy and precision of our ion selective electrode analysis were confirmed by similarity to ultrafiltrable Ca level cut-off molecular weight 1, 000.
Total Ca levels ranged from 5.6 to 16.3mg/dl, and these levels were well correlated with biliary lipid concentrations. Unlike total Ca, Ca²⁺ concentration remained almost constant level (2.40±0.63mg/dl), regardless of the change in biliary lipid concentration. This findings was confirmed by the recovery test for addition of Ca²⁺ and dilution test adding saline solution to gallbladder bile.
In conclusion, total Ca level was dependent on biliary lipid concentration, while Ca²⁺ level was independent and kept a constant value, probably owing to the regulating role of the mixed micelle in gallbladder bile.