Certified Surgical Technologist (CST) Exam 2025 – 400 Free Practice Questions to Pass the Exam

The hormone primarily involved in regulating the menstrual cycle is estrogen. Estrogen plays a crucial role in the development and regulation of the reproductive system and secondary sexual characteristics. During the menstrual cycle, estrogen levels fluctuate, contributing to the thickening of the uterine lining (endometrium) in preparation for potential implantation of a fertilized egg.

In the first half of the cycle, known as the follicular phase, estrogen is produced mainly by developing follicles in the ovaries. This hormone triggers the release of luteinizing hormone (LH), which leads to ovulation. Following ovulation, the corpus luteum secretes estrogen and progesterone, maintaining the uterine lining. If pregnancy does not occur, estrogen and progesterone levels drop, resulting in menstruation marking the end of the cycle.

Insulin is primarily involved in glucose metabolism, cortisol is related to stress response, and testosterone is more associated with male reproductive functions, though it does have some role in female physiology. However, none of these hormones directly regulate the menstrual cycle like estrogen does.