['The primary objective of this study was to test the hypothesis that calcium alone does not account for the observed coagulation differences between saline-based and balanced electrolyte IV fluid preparations.', 'Controlled, nonblinded, in vitro observational study.', 'University-based anesthesia research laboratory.', 'Ten healthy volunteers.', "The volunteers donated fresh blood for in vitro 40% and 60% dilution with 6 intravenous fluid preparations (lactated Ringer's solution, human albumin solution, and 4 hydroxyethyl starch preparations). All saline-based fluids were supplemented with calcium chloride to obtain ionized concentrations >or=1.0 mmol/L.", 'After dilution of the fresh blood with the study fluids, samples were analyzed by using the Thrombelastograph. Three colloid preparations produced minimal coagulation derangement, even at 60% dilution (human albumin solution, tetrastarch in saline, and pentastarch in balanced electrolyte solution), whereas pentastarch in saline and hetastarch in balanced electrolyte produced a mildly hypocoagulable state at 60% dilution.'] Does calcium supplementation of saline-based colloids produce equivalent coagulation profiles to similarly balanced salt preparations?