dromlakhani Measure nadir GH after glucose load if postoperative GH >1 µg/L
STEP 1 — Gather Information
Confirm postoperative timing ≥12 weeks after transsphenoidal surgery; obtain serum IGF-1 and random GH levels.
STEP 2 — Rule In / Rule Out
Is random GH >1 µg/L? If NO, consider biochemical remission (especially if IGF-1 normal) and routine follow‑up. If YES, proceed to oral glucose tolerance test (OGTT) for nadir GH measurement.
STEP 3 — Classify or Stratify
Perform OGTT (75 g glucose) and measure nadir GH at 0, 30, 60, 90, 120 min; classify as suppressed if nadir GH <1 µg/L, not suppressed if nadir GH ≥1 µg/L.
STEP 4 — Decide
If nadir GH suppressed (<1 µg/L), continue routine surveillance with IGF-1 and random GH every 6‑12 months. If nadir GH not suppressed (≥1 µg/L), consider persistent disease and discuss repeat surgery, medical therapy, or radiotherapy with multidisciplinary team.
Clinical Guardrails / Mimics / Pitfalls
Do not measure GH <12 weeks post‑op due to surgical stress‑induced elevations; ensure fasting state and verify hyperglycemia during OGTT to avoid false‑negative suppression; use assay with adequate sensitivity at low GH levels; do not rely solely on random GH without IGF-1 context; avoid interpreting a single nadir GH without confirming glucose load adequacy.
Concrete Clinical Example
A patient 4 months postoperatively has random GH 1.8 µg/L and IGF-1 above age‑adjusted norm. OGTT yields nadir GH 0.9 µg/L (<1 µg/L), indicating adequate suppression; patient continues routine monitoring. Another patient with random GH 2.2 µg/L has nadir GH 1.6 µg/L (≥1 µg/L), prompting discussion of repeat surgery or initiation of somatostatin receptor ligand therapy.
Source: Acromegaly: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2014, DOI:10.1210/jc.2014-2700
TODO: consider adding scripts/calc.py for the endo-postop-nadir-gh-ogtt-if-ghgt1 calculator