Influence of 25% human serum albumin on total and ionized calcium concentrations in vivo

Introduction: A inverse correlation has been found between changes in ionized calcium concentrations (physiologically active form) and the addition of albumin in vitro, which may explain adverse cardiovascular effects attributed to exogenous albumin in vivo. The purpose of this investigation was to determine the interaction (if any) between exogenous 25% albumin administration and calcium concentrations in unstable patients. Methods: Following a retrospective analysis involving critically ill patients in which no effect of 25% albumin on ionized calcium concentrations was noted, nine patients were studied prospectively. With one exception, all patients were studied in the ICU. Concentrations of albumin, total and ionized calcium were obtained within one hour prior to the start of a 25% 100 mL albumin infusion given over less than one-half hour, and then at the end and six hours after the infusion. The commercially-available albumin product was tested to ensure that it did not contain substantial amounts of calcium. No other albumin-containing products were administered during the study periods. Results: There were no significant differences in either the ionized or total calcium concentrations obtained before and after the administration of albumin. Ionized calcium in mMol/L*Total calcium in mg/dL Pre/1 h post/6 h post Pre/1 h post/6 h post Concentrations 1.09(0.23)/1.06(0.22)/1.06(0.21) 8.1(0.7)/8.2(0.8)/8.3(.9)*all values expressed as mean (SD); no significant differences by ANOVA Conclusions: In patients receiving relatively rapid infusions of 25% albumin, it appears that circulating calcium concentrations are well-regulated by homeostatic mechanisms. Albumin infusions had no effect on either ionized or total calcium concentrations, although it is possible that temporary changes of questionable clinical importance may have occurred between measurement periods.