ata-cortisol-cutoff-ai-diagnosis

name	ata-cortisol-cutoff-ai-diagnosis
description	Applies serum cortisol cutoffs (<3 μg/dL indicates central adrenal insufficiency; >15 μg/dL likely excludes it) when evaluating morning cortisol for suspected adrenal insufficiency. Triggers include morning cortisol measurement in suspected AI and use when interpreting morning cortisol levels for adrenal insufficiency workup.

Apply cortisol level cutoffs for central AI diagnosis

STEP 1 — Gather Information

Collect morning serum cortisol drawn between 8–9 AM after an overnight fast; document recent glucocorticoid exposure (must be off hydrocortisone ≥24 h or longer for synthetic GCs); note estrogen therapy, pregnancy, or medications affecting cortisol-binding globulin; record any acute illness or stress that could alter cortisol.

STEP 2 — Rule In / Rule Out

Is the morning cortisol level <3 μg/dL?

• If yes, rule in central AI (indicative).
• If no, proceed to next step.

STEP 3 — Classify or Stratify

Is the cortisol level between 3 and 15 μg/dL (inclusive)?

• If yes, classify as indeterminate; ACTH stimulation test required.
• If no (i.e., >15 μg/dL), classify as AI unlikely excluded.

STEP 4 — Decide

• For cortisol <3 μg/dL: initiate glucocorticoid replacement (e.g., hydrocortisone 15–20 mg daily) and provide stress‑dose education.
• For cortisol 3–15 μg/dL: order standard‑ or low‑dose ACTH stimulation test to confirm AI.
• For cortisol >15 μg/dL: consider alternative diagnoses; avoid glucocorticoid replacement unless other evidence of AI exists.

Clinical Guardrails / Mimics / Pitfalls

Do not use random cortisol levels; estrogen therapy or pregnancy raises total cortisol via CBG, potentially masking AI; ensure patient is off glucocorticoids for adequate time; acute illness or stress can transiently elevate cortisol; assay variability and inter‑lab differences may affect cutoff interpretation; avoid glucocorticoid replacement based solely on a single borderline result without stimulation testing.

Concrete Clinical Example

A 48‑year‑old man with persistent fatigue and hypotension has a morning cortisol of 2.4 μg/dL drawn at 8:30 AM after being off hydrocortisone for 36 hours. The value is <3 μg/dL, indicating central AI; he is started on hydrocortisone 15 mg daily and instructed on stress‑dosing for illness.

Source: Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2016, DOI:10.1210/jc.2016-2118

TODO: consider adding scripts/calc.py for the ata-cortisol-cutoff-ai-diagnosis calculator