Hormone Testing for Women with Weight Gain
Women with weight gain should have hormone testing only if they have accompanying menstrual irregularities, signs of hyperandrogenism (hirsutism, acne), or other clinical features suggesting endocrine dysfunction—isolated weight gain alone does not warrant routine hormonal screening. 1, 2
Clinical Algorithm for Deciding When to Test
Test hormones if weight gain occurs WITH any of these features:
- Menstrual irregularities: cycles <23 days (polymenorrhoea), >35 days (oligomenorrhoea), or amenorrhea >6 months 1
- Hirsutism or acne: male-pattern hair growth or persistent acne suggesting hyperandrogenism 1
- Infertility: inability to conceive after 12 months of unprotected intercourse 1
- Galactorrhea: nipple discharge or crusting suggesting hyperprolactinemia 1
- Central obesity: waist-to-hip ratio >0.9 with menstrual disturbance 1
Do NOT routinely test hormones if:
- Weight gain is isolated without menstrual irregularities or other endocrine symptoms 2
- BMI increase alone without clinical features of endocrine syndromes 2
Specific Hormone Panel When Testing is Indicated
Order these tests between cycle days 3-6 (three samples 20 minutes apart for LH/FSH): 1, 3
- LH and FSH: LH/FSH ratio >2 suggests PCOS; FSH >35 IU/L suggests premature ovarian failure 1, 3
- TSH: screen for hypothyroidism (abnormal if >2 mIU/L in PCOS context, as TSH ≥2 associates with insulin resistance independent of BMI) 1, 4, 5
- Prolactin: morning resting sample; >20 μg/L is abnormal and requires exclusion of hypothyroidism and pituitary pathology 1, 3
- Mid-luteal progesterone: <6 nmol/L indicates anovulation, common in PCOS 1
- Total testosterone: >2.5 nmol/L suggests PCOS or other hyperandrogenic states 1, 3
- Fasting glucose and insulin: calculate glucose/insulin ratio; ratio >4 suggests reduced insulin sensitivity 1, 3
Evidence-Based Rationale
Weight gain is a trigger for PCOS development, not a primary diagnostic criterion. 1 Women with PCOS experience significantly greater weight gain over 10 years compared to unaffected women (mean 2.6 kg additional gain), and each BMI unit increase raises PCOS prevalence by 9%. 6 However, this bidirectional relationship means weight gain can worsen underlying PCOS rather than being caused by new hormonal dysfunction. 1
The European Society of Endocrinology explicitly recommends against routine endocrine testing in obesity without clinical features of endocrine syndromes. 2 With the exception of TSH screening for hypothyroidism, most hormone testing yields low diagnostic value in isolated weight gain. 2
PCOS affects 4-6% of the general population and is the most common hormonal cause of weight gain in reproductive-age women. 1 However, PCOS diagnosis requires menstrual irregularity or hyperandrogenism—not just weight gain. 1 Women with PCOS have significantly higher odds of insulin resistance (OR 4.8), hypothyroidism (OR 4.29), and hyperprolactinemia (OR 4.27) compared to controls. 4
Critical Pitfalls to Avoid
- Do not screen for hormones based solely on weight gain without menstrual or hyperandrogenic symptoms—this leads to unnecessary testing and false-positive results. 2
- Do not miss thyroid screening when testing is indicated—hypothyroidism occurs in 43% of women with hyperprolactinemia and TSH ≥2 mIU/L associates with insulin resistance independent of age and BMI in PCOS. 3, 4, 5
- Do not order isolated testosterone without checking menstrual regularity first—hyperandrogenism without menstrual dysfunction may represent normal variation or ethnic differences. 1
- Do not forget that weight loss itself corrects many endocrine abnormalities—successful weight reduction has a high likelihood of normalizing hormone dysfunction without specific hormone treatment. 2
When to Refer for Specialist Evaluation
Refer to endocrinology or gynecology if: 3