In PCOS, which lab pattern is most characteristic?

In PCOS, which lab pattern is most characteristic?

• A. Decreased LH, increased FSH, low testosterone.
• B. Increased LH:FSH ratio with increased testosterone and low SHBG.
• C. Elevated FSH only.
• D. Decreased LH with high SHBG.

Answer: (B)

In PCOS, the most characteristic lab pattern reflects hyperandrogenism with disrupted ovulatory function. Luteinizing hormone tends to be high relative to follicle-stimulating hormone, producing an increased LH:FSH ratio (often around 2:1 or 3:1). This shift drives the ovarian theca cells to produce more androgens, so you see elevated testosterone levels. At the same time, FSH is not elevated enough to support normal follicle maturation and the aromatization of androgens to estrogen by granulosa cells, contributing to anovulation and the appearance of polycystic ovaries. Insulin resistance, common in PCOS, lowers hepatic production of SHBG, so more testosterone remains unbound and biologically active (low SHBG). The combination of higher androgens and lower SHBG explains the clinical features of hyperandrogenism, such as hirsutism and acne, and irregular menses. So the hallmark pattern is an increased LH:FSH ratio with elevated testosterone and low SHBG.

In PCOS, the most characteristic lab pattern reflects hyperandrogenism with disrupted ovulatory function. Luteinizing hormone tends to be high relative to follicle-stimulating hormone, producing an increased LH:FSH ratio (often around 2:1 or 3:1). This shift drives the ovarian theca cells to produce more androgens, so you see elevated testosterone levels. At the same time, FSH is not elevated enough to support normal follicle maturation and the aromatization of androgens to estrogen by granulosa cells, contributing to anovulation and the appearance of polycystic ovaries.

Insulin resistance, common in PCOS, lowers hepatic production of SHBG, so more testosterone remains unbound and biologically active (low SHBG). The combination of higher androgens and lower SHBG explains the clinical features of hyperandrogenism, such as hirsutism and acne, and irregular menses.

So the hallmark pattern is an increased LH:FSH ratio with elevated testosterone and low SHBG.