What are the typical levels of Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), Estradiol, Anti-Müllerian Hormone (AMH), Thyroid-Stimulating Hormone (TSH), and Prolactin in a patient with Polycystic Ovary Syndrome (PCOS)?

Typical Hormone Levels in PCOS Patients

In PCOS patients, expect elevated LH (often with LH:FSH ratio >2 in 35-44% of cases), elevated AMH (typically >5 ng/mL), normal to elevated estradiol, normal FSH, and normal TSH and prolactin—though the latter two must be measured to exclude other diagnoses.

Luteinizing Hormone (LH)

• LH levels are elevated in approximately 75% of anovulatory PCOS patients, with levels typically above the 95th percentile of normal controls 1
• The classic LH:FSH ratio >2 is present in only 35-44% of PCOS patients, making it a poor standalone diagnostic marker 2
• LH levels show significant variability and are inversely correlated with body mass index—obese PCOS patients often have normal or even low LH levels due to decreased LH pulse amplitude 1
• During GnRH stimulation testing, PCOS women demonstrate stimulated LH levels of approximately 35.48 ± 31.4 IU/L 3
• Important caveat: Isolated LH measurements may not be sufficiently reproducible to be clinically useful, as values can fluctuate significantly over time 4

Follicle-Stimulating Hormone (FSH)

• FSH levels are typically normal or low-normal in PCOS patients 3, 5
• FSH remains within the broad normal range in approximately 80% of anovulatory PCOS patients 5
• The key finding is not absolute FSH level but rather the elevated LH:FSH ratio, which is abnormal in 94% of anovulatory PCOS patients 1

Estradiol

• Estradiol levels are usually within normal range but may be tonically elevated in PCOS patients 5
• Unlike functional hypothalamic amenorrhea where estradiol is <100 pmol/L, PCOS patients maintain normal to elevated estrogen production 3
• Estradiol does not correlate significantly with LH levels in PCOS patients 1

Anti-Müllerian Hormone (AMH)

• AMH is markedly elevated in PCOS, with levels typically ≥35 pmol/L (5 ng/mL) showing 92% sensitivity and 97% specificity 2
• Age-specific cut-off values are more accurate: >5.56 ng/mL for ages 21-25 years, >4.01 ng/mL for ages 26-30 years, and >3.42 ng/mL for ages 31-35 years 6
• AMH levels increase progressively with higher LH:FSH ratios, demonstrating a positive correlation between LH and AMH 3, 7
• AMH shows strong correlation with antral follicle count across all age groups 6
• Critical limitation: Despite high sensitivity and specificity, AMH should not be used as a standalone diagnostic test due to lack of assay standardization and absence of validated cut-offs across different populations 2

Thyroid-Stimulating Hormone (TSH)

• TSH levels should be normal in PCOS patients—measuring TSH is mandatory to exclude thyroid disease as an alternative cause of menstrual irregularity 2
• TSH may be slightly elevated in some PCOS cohorts, but this represents comorbid thyroid dysfunction rather than a feature of PCOS itself 7
• Any abnormal TSH requires further thyroid evaluation before confirming PCOS diagnosis 2

Prolactin

• Prolactin levels should be normal in PCOS—elevated prolactin excludes the diagnosis and indicates hyperprolactinemia as the cause of symptoms 2
• Morning resting serum prolactin should be measured, with levels >20 μg/L considered abnormal 2
• Important pitfall: Confirm prolactin elevation with 2-3 samples at 20-60 minute intervals via indwelling cannula to exclude stress-related spurious elevation 2

Additional Hormone Patterns

• Testosterone and free androgen index are elevated in PCOS, with total testosterone showing 74% sensitivity and 86% specificity when measured by LC-MS/MS 2
• As LH levels and LH:FSH ratios increase across PCOS subgroups, insulin, testosterone, and AMH levels increase proportionally while SHBG decreases 7
• SHBG is typically decreased in PCOS patients, particularly those with higher LH levels 3
• Insulin levels are elevated with positive correlation to LH levels, suggesting interdependence of insulin, LH, and testosterone in PCOS pathophysiology 7

Clinical Interpretation Caveats

• Recent spontaneous ovulation normalizes LH levels—approximately 15% of PCOS patients studied within 21 days after documented ovulation have normal pool LH levels 1
• Obesity significantly modifies hormone patterns—there is a strong negative correlation (R = -0.59) between BMI and LH levels, with obese PCOS patients showing decreased LH pulse amplitude 1
• The heterogeneity of hormone levels in PCOS reflects a continuous spectrum rather than distinct pathophysiologic subsets 1