Endo Fha Endocrine Labs

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name: endo-fha-endocrine-labs
description: This skill guides clinicians to obtain an initial endocrine laboratory evaluation for functional hypothalamic amenorrhea, measuring serum TSH, free T4, prolactin, LH, FSH, estradiol, and AMH, with addition of total testosterone and DHEA-S if hyperandrogenism is present and 8 AM 17-hydroxyprogesterone if late-onset CAH is suspected. Use when a clinician states, “We need a full endocrine panel to assess thyroid, gonadal, and adrenal function,” or uses trigger phrases such as “Check TSH, prolactin, and LH/FSH” or “Get estradiol and AMH for ovarian reserve.”
---

# Obtain endocrine laboratory evaluation

## STEP 1 — Gather Information
Collect menstrual history (amenorrhea ≥3 months or cycle >45 days), assess for pregnancy, and evaluate for clinical hyperandrogenism (hirsutism, acne, virilization) or signs suggestive of late-onset congenital adrenal hyperplasia (precocious puberty, hypertension, electrolyte abnormalities).

## STEP 2 — Rule In / Rule Out
Rule out pregnancy via urine or serum hCG; if positive, manage pregnancy and do not proceed with this endocrine panel. If negative, continue to next step.

## STEP 3 — Classify or Stratify
Determine whether to add targeted assays: if clinical hyperandrogenism is present, add total testosterone and DHEA-S; if late-onset CAH is suspected, add 8 AM 17-hydroxyprogesterone.

## STEP 4 — Decide
Order the base panel (TSH, free T4, prolactin, LH, FSH, estradiol, AMH) plus any indicated additional tests based on stratification; draw blood preferably in the early follicular phase if timing is known, but results are interpretable regardless of cycle day for most assays.

## Clinical Guardrails / Mimics / Pitfalls
Do not order these labs without first excluding pregnancy; avoid interpreting a single estradiol value as diagnostic of FHA; do not rely on LH/FSH ratio alone to differentiate FHA from PCOS; do not obtain 17-OHP without clinical suspicion for CAH; do not order testosterone/DHEA-S in the absence of hyperandrogenism signs.

## Clinical Example
A 24-year-old runner presents with 5 months of amenorrhea, BMI 17.2, and no hirsutism. Pregnancy test is negative. She denies virilization or CAH symptoms. Order TSH, free T4, prolactin, LH, FSH, estradiol, and AMH. No testosterone/DHEA-S or 17-OHP added.

**Source:** Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2017, DOI:10.1210/jc.2017-00131