TOTAL SERUM-CALCIUM REFERENCE INTERVALS IN POSTMENOPAUSAL OUTPATIENTS

The distribution of values of serum calcium has been studied in the fo llowing four outpatient populations: premenopausal (n = 411) and postm enopausal women (n = 399), men less than 50 years old (n = 365) and me n over 55 years old (n = 361). Their respective average total serum ca lcium values (mg/dl) were 9.42, 9.56, 9.53, and 9.45. The reference in tervals derived for total serum calcium (mg/dl) were 8.4-10.3 (premeno pausal women), 8.4-10.7 (postmenopausal women), 8.6-10.5 (men less tha n 50 years old), and 8.4-10.4 (men over 55 years old). Increased total serum calcium levels were observed in the postmenopausal women as com pared with both premenopausal women (p < 0.001) and with men over 55 y ears old (p < 0.003). Eight percent of the values obtained in postmeno pausal women were above the current reference interval, as compared to 1.7% in premenopausal women, and 3.3% in men over 55 years old. In co nclusion, the age-related increase in total serum calcium in postmenop ausal female outpatients warrants a higher upper limit of the referenc e interval for this subpopulation.