Calculation of estrogen excretion rates from urinary estrogen to creatinine ratios.

1. The excretion of estrogens by 42 menstruant and 7 pregnant (1st trimester) women ranged from 2 - 550 mug/24hr. 2. These changes were followed by measuring estrogen to creatinine ratios in small samples of urine. 3. Values of the ratio changed little in each 24 hr, and correlated closely with daily estrogen output (r = 0.971; P less than 0.001; estrogens (mug/24hr) =(see article. 4. The data suggests that ovarian activity in women, including those given gonadotropins to induce ovulation, may be followed by measuring estrogen to creatinine ratios in small samples of urine; the collection of 24 hr samples is unnecessary.