Individual Variation in Serum Calcium in Normal Men and Women. ∗

Abstract

Since the work of Bell 1 many investigators have studied the blood calcium level in relation to menstruation. The results of these investigations have been contradictory. Watchorn 2 , Close and Osman 3 , Allen and Goldthorpe 4 , Spiegler 5 , and others have concluded that there is very little or no change in the blood calcium in relation to the menstrual cycle. Sharlit et al 6 and Matters 7 report a premenstrual rise in blood calcium and a menstrual fall in the calcium level. Okey et al 8 state that “while the changes in the concentration of serum calcium at any phase of the monthly cycle are not outstanding, there is some tendency to frequency of low values for calcium a few days previous to the onset of menstruation and to frequency of higher values from the 8th to the 15th days following the onset of menstrual bleeding.”

With the exception of the work of Okey et al 8 , these findings have been based upon either the study of very small groups of individuals or upon blood calcium determinations taken not more than 3 or 4 times during a menstrual cycle.

Experimental work done on lower animals shows that the blood calcium level is definitely affected by the reproductive system. Riddle and Reinhart 9 found a tremendous increase in calcium in the blood of birds prior to ovulation. Mirvish and Bosman 10 have produced a decrease of 2 to 3 mg. in the plasma calcium in both rabbits and human beings by injecting ovarian follicular and corpus luteum extracts.

The present study was undertaken in an effort to determine standards of blood calcium in relation to the menstrual cycle in women with normal menstrual periods in order that we might have some basis for comparison in a study being made on a group of women with dysmenorrhea.