In PCOS, what hormonal change is described as contributing to irregular menstrual cycles?

• A. Excess testosterone production with lowered FSH and LH levels
• B. Increased progesterone with normal FSH
• C. Low estrogen with high FSH
• D. Decreased prolactin with increased LH

Answer: (A)

The key idea is that irregular menstrual cycles in PCOS come from not ovulating regularly due to a hormonal environment that drives excess androgens. In PCOS the ovaries produce more testosterone (hyperandrogenism) because the theca cells are stimulated by LH and, often with insulin resistance, there’s an overall push toward androgen production. This excess testosterone disrupts normal follicle development and prevents the dominant follicle from properly maturing and ovulating. Without ovulation, the luteal phase doesn’t occur, so cycles become irregular or absent.

So the choice that emphasizes excess testosterone reflects this fundamental link: hyperandrogenism is a hallmark of PCOS and directly contributes to anovulatory cycles and irregular menses through impaired follicle maturation and ovulation. The other patterns described—such as an increased progesterone indicating a luteal phase, or a pattern suggestive of ovarian failure or prolactin-driven issues—don’t fit the typical PCOS mechanism as well.