dromlakhani Select provocative test for GHD diagnosis
STEP 1 — Gather Information
Collect history of cranial/spinal radiation dose, presence of seizure disorder or significant cardiac disease, symptoms of GHD (growth deceleration, low IGF-I, increased fat mass), baseline IGF-I level, and number of other confirmed anterior pituitary hormone deficits.
STEP 2 — Rule In / Rule Out
If the patient has three or more other confirmed anterior pituitary hormone deficits, skip provocative testing for GHD (per 2.6); otherwise proceed to evaluate test options.
STEP 3 — Classify or Stratify
Classify test suitability: avoid insulin tolerance test (ITT) in seizure disorder or coronary artery disease; avoid glucagon test in insulinoma; avoid GHRH alone if hypothalamic-pituitary radiation damage is suspected; otherwise prefer ITT (most reliable) or glucagon/arginine as alternatives.
STEP 4 — Decide
Order the selected provocative test using established GH cut-offs (e.g., ITT peak GH <5 µg/L, glucagon <3 µg/L, arginine <0.4 µg/L) to confirm or exclude GHD.
Clinical Guardrails / Mimics / Pitfalls
Do not use ITT in patients with uncontrolled seizure disorder or significant cardiac disease; do not use glucagon in insulinoma; do not rely on GHRH alone after hypothalamic radiation; do not use spontaneous GH secretion as a diagnostic test; do not rely solely on IGF-I levels for diagnosis.
Concrete Clinical Example
A 16-year-old medulloblastoma survivor who received 24 Gy craniospinal radiation presents with slowed growth velocity and low IGF-I. No seizures or cardiac disease. Three other hormone deficits are absent. ITT is selected as the preferred test due to its reliability and absence of contraindications.
Source: Hypothalamic Pituitary and Growth Disorders in Survivors of Childhood Cancer: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2018, DOI:10.1210/jc.2018-01175