Estradiol (E2)

Estradiol (E2) is the main active estrogen in men, mostly made by conversion from testosterone. It supports bone and sexual function, but high levels can contribute to gynecomastia, fluid retention, and lower libido. Interpret alongside testosterone and SHBG.

Estradiol (E2) is the main active estrogen in women and is produced mainly by the ovaries. It regulates the menstrual cycle and ovulation, and supports bone and reproductive health. Levels change a lot across the cycle, so interpretation depends on cycle day and hormone use.