Bolus injections of recombinant human interleukin-1 cause transient hypocalcemia in normal mice.

Single daily injections of recombinant human interleukin-1 alpha (IL-1 alpha) or interleukin-1 beta (IL-1 beta) were given for 1-3 days to normal mice, and blood ionized calcium concentrations were measured before and at various times after each injection. Mean blood calcium levels fell significantly in both groups of animals 3 h after the first IL-1 injections and returned to pretreatment values at 5 h. However, at 24 and 48 h mean values were significantly higher than those in saline-heated controls. Despite this progressive underlying increase in mean blood ionized calcium concentrations, blood calcium concentrations also fell significantly 3 h after the second and third IL-1 injections. The transient decrease in blood calcium was prevented by treatment with indomethacin and, thus, appears to be prostaglandin mediated. Hypocalcemia was not observed after single bolus injections of tumor necrosis factor-alpha or -beta (lymphotoxin). These findings suggest that IL-1 is a potential mediator of the hypocalcemia that occurs in up to 40% of patients with bacteremic sepsis and severe tissue injury and is associated with an increased mortality rate.