Endo Fha Screening Labs

---
name: endo-fha-screening-labs
description: This skill recommends obtaining initial screening laboratory tests for functional hypothalamic amenorrhea (FHA) to rule out pregnancy and systemic illness. Use when a clinician states, 'Let’s get basic labs to rule out pregnancy and systemic illness,' or similar phrases such as 'Order a chem panel and pregnancy test' or 'Check CBC and metabolic panel'.
---

# Order initial screening laboratory tests

## STEP 1 — Gather Information
Collect menstrual history (amenorrhea ≥3 months or cycle >45 days), assess for pregnancy symptoms, evaluate for stressors, weight loss, exercise intensity, eating disorders, and medication use. If FHA is suspected based on history, proceed to order initial screening labs.

## STEP 2 — Rule In / Rule Out
Order serum b-hCG to rule out pregnancy. If positive, diagnose pregnancy and manage accordingly; if negative, continue to evaluate for systemic illness.

## STEP 3 — Classify or Stratify
Review CBC, electrolytes, glucose, bicarbonate, BUN, creatinine, liver panel, and ESR/CRP for abnormalities suggestive of chronic illness. If any abnormal, classify as possible systemic illness; if all normal, classify as unlikely systemic illness.

## STEP 4 — Decide
If labs suggest systemic illness, investigate underlying cause before attributing amenorrhea to FHA. If labs are normal, proceed with endocrine evaluation (TSH, free T4, prolactin, LH, FSH, estradiol, AMH).

## Clinical Guardrails / Mimics / Pitfalls
Do not diagnose FHA without excluding pregnancy and systemic illness; avoid interpreting isolated lab abnormalities without clinical context; do not delay pregnancy test in sexually active patients; refrain from ordering extensive endocrine panels before basic screening labs are completed.

## Concrete Clinical Example
A 19‑year‑old collegiate runner presents with 4 months of amenorrhea after increasing training and losing weight. She denies pregnancy symptoms. b‑hCG is negative; CBC, CMP, and ESR are normal. Labs are normal, so endocrine evaluation with TSH, free T4, prolactin, LH, FSH, estradiol, and AMH is pursued.

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