AAMC FL Practice Exam

What hormonal control is triggered by an increase in estrogen levels during the menstrual cycle?

1. FSH

2. Testosterone

3. LH

4. Prolactin

The correct answer is: LH

During the menstrual cycle, an increase in estrogen levels triggers a surge in luteinizing hormone (LH) production, which plays a crucial role in the ovulation process. As the follicles in the ovaries mature, they produce more estrogen, especially estradiol. When estrogen levels reach a certain threshold, they exert positive feedback on the anterior pituitary gland, stimulating it to release a significant amount of LH. This LH surge is essential as it causes the mature follicle to release an egg from the ovary, a process known as ovulation. Without this increase in LH, ovulation would not occur, demonstrating the vital interplay between estrogen and LH in the menstrual cycle. Testosterone is not directly influenced by estrogen levels in this context; instead, it is primarily regulated by luteinizing hormone in males. Follicle-stimulating hormone (FSH) does play a role in the menstrual cycle, particularly in stimulating the growth of ovarian follicles, but it does not respond to estrogen in the same way as LH does. Prolactin is primarily involved in lactation and does not play a direct role in the hormonal control of the menstrual cycle. Thus, LH is the hormone whose surge is specifically triggered by increased estrogen levels during this phase