Endo Igf1 Pituitary Mass Ruleout

---
name: endo-igf1-pituitary-mass-ruleout
description: Recommends measuring serum IGF-1 to exclude acromegaly in any patient discovered to have a pituitary mass on imaging. Triggers include incidental pituitary lesion found on MRI/CT for unrelated reasons.
---

# Measure IGF-1 to rule out acromegaly in pituitary mass

## STEP 1 — Gather Information
Collect imaging report confirming pituitary mass and order serum IGF-1 measurement.

## STEP 2 — Rule In / Rule Out
If serum IGF-1 is age-adjusted normal, rule out acromegaly; if elevated or equivocal, proceed to GH suppression testing.

## STEP 3 — Classify or Stratify
Perform oral glucose tolerance test (OGTT) with GH measurement; decide based on GH suppression: if GH suppresses <0.4 µg/L, acromegaly unlikely; if not suppressed, diagnose acromegaly.

## STEP 4 — Decide
If acromegaly is ruled out, pursue alternative etiology of pituitary mass; if confirmed, refer to endocrine surgery or medical therapy per guideline.

## Clinical Guardrails / Mimics / Pitfalls
Do not rely on random GH alone; normal IGF-1 may be falsely low in pregnancy, renal/hepatic failure, malnutrition, or hypothyroidism. Assay variability requires age‑adjusted norms and same‑lab repeat if equivocal. Elevated IGF-1 alone is insufficient for diagnosis; confirm with OGTT.

## Concrete Clinical Example
A 52‑year‑old undergoes head CT for trauma and incidentally shows a 8 mm pituitary lesion. Serum IGF-1 is age‑adjusted normal. Acromegaly is ruled out; further workup focuses on trauma‑related findings.

**Source:** Acromegaly: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2014, DOI: 10.1210/jc.2014-2700