Are estrogen assays essential for monitoring gonadotropin stimulant therapy?

Ovarian responses to human menopausal gonadotropin (hMG) are conventionally monitored by urinary estrogen or serum estradiol (E2) concentration. E2 can also be measured in saliva but this is rarely used. With ultrasound (USS) however, follicular development is assessed directly and we have previously shown that USS is superior to urinary estrogens for monitoring. We have now compared salivary and serum E2 with USS during hMG therapy in 48 women over 101 cycles. Salivary and serum E2 correlated significantly with each other and with the number of mature follicles. The manufacturers of hMG state that hCG should be given only when E2 is between 100 and 3000 pmol/l. However, there were no mature follicles in 40% of the cycles where E2 lay within this range. USS is the most accurate method of monitoring responses to hMG and, where this is available, estrogen assay provides no additional useful information.