Endo Hirsutism Dexamethasone Suppression Test

Perform dexamethasone suppression testing to evaluate functional adrenal androgen excess

STEP 1 — Gather Information

Collect menstrual history, Ferriman–Gallwey score, signs of virilization (clitoromegaly, deepening voice, rapid muscle gain), baseline early‑morning serum total testosterone, free testosterone, DHEAS, androstenedione, and 17‑hydroxyprogesterone. Note any use of exogenous glucocorticoids or medications that affect adrenal function.

STEP 2 — Rule In / Rule Out

Is there clinical evidence of a hyperandrogenic disorder (e.g., menstrual irregularity, infertility, rapid hirsutism progression, or signs of virilization) despite normal total and free testosterone?

• Yes: Proceed to dexamethasone suppression test.
• No: Consider alternative etiologies (e.g., idiopathic hirsutism, ovarian sources) and do not perform DST.

STEP 3 — Classify or Stratify

Administer 0.5 mg dexamethasone orally at midnight and draw serum the next morning (8–9 am) for DHEAS, androstenedione, and cortisol.

• Suppression: ≥50% decrease in DHEAS or androstenedione from baseline suggests functional adrenal androgen excess.
• No suppression: <50% decrease makes a functional adrenal source unlikely; consider adrenal tumor or other causes.

STEP 4 — Decide

If suppression is confirmed, consider a trial of low‑dose nocturnal dexamethasone (0.25–0.5 mg at bedtime) to reduce adrenal androgen production, with monitoring of clinical response and hormone levels.
If no suppression, pursue adrenal imaging (CT/MRI) to rule out adrenal neoplasm and reassess ovarian sources.

Clinical Guardrails / Mimics / Pitfalls

Do not use DST to diagnose Cushing’s syndrome; avoid testing in pregnancy or while on exogenous glucocorticoids, which can cause false suppression. Ensure the sample is drawn early morning after an overnight fast, and verify that the patient has not missed doses or taken interacting drugs (e.g., enzyme inducers). A normal DST does not exclude mild adrenal hyperplasia; clinical judgment remains essential.

Concrete Clinical Example

A 28‑year‑old woman presents with Ferriman–Gallwey score 18, oligomenorrhea, and normal total testosterone (35 ng/dL). She reports gradual worsening of facial hair over 6 months despite cosmetic measures. Baseline DHEAS is 280 µg/dL (upper limit normal). After 0.5 mg dexamethasone at midnight, morning DHEAS falls to 110 µg/dL (61 % suppression). Low‑dose nocturnal dexamethasone 0.25 mg nightly is started; after 3 months her FG score improves to 12 and menses regularize.

Source: Evaluation and Treatment of Hirsutism in Premenopausal Women: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2018, https://doi.org/10.1210/jc.2018-00241