Ata Ppgl Radionuclide Therapy Selection

---
name: ata-ppgl-radionuclide-therapy-selection
description: The skill selects 131I-MIBG therapy for pheochromocytoma or paraganglioma with positive 123I-MIBG scintigraphy that reduces excess catecholamines, or 177Lu-DOTATATE therapy for lesions with positive somatostatin receptor scintigraphy, both modalities covered by Japanese health insurance. It is invoked when a clinician asks which radionuclide therapy to use for metastatic or unresectable PPGL amenable to targeted treatment.
---

# Select radionuclide therapy for pheochromocytoma and paraganglioma

## STEP 1 — Gather Information
Confirm metastatic or unresectable PPGL amenable to targeted radionuclide therapy; obtain 123I-MIBG scintigraphy (e.g., diagnostic 123I-MIBG SPECT/CT) and somatostatin receptor scintigraphy (e.g., 68Ga-DOTATATE PET/CT or 111In-octreotide SPECT) to assess tracer avidity.

## STEP 2 — Rule In / Rule Out
Is the 123I-MIBG scintigraphy positive (avid uptake in lesion)? If yes, rule in for 131I-MIBG therapy; if negative, proceed to evaluate somatostatin receptor scintigraphy.

## STEP 3 — Classify or Stratify
If 123I-MIBG negative, assess somatostatin receptor scintigraphy: positive uptake indicates eligibility for 177Lu-DOTATATE; if both studies are negative, radionuclide therapy is not indicated (consider alternative systemic treatments).

## STEP 4 — Decide
For 123I-MIBG-positive PPGL: administer 131I-MIBG 5.55–7.4 GBq intravenously over 1 hour with thyroid blockade (potassium iodide 130 mg/day 1–3 days before to 7 days after). For somatostatin receptor‑positive PPGL: administer 177Lu-DOTATATE 7.4 GBq intravenously over 30 minutes, repeat up to four times at 8‑week intervals.

## Clinical Guardrails / Mimics / Pitfalls
Do not rely solely on 123I-MIBG in SDHx‑variant PPGL where false negatives occur; avoid 177Lu-DOTATATE if somatostatin receptor scan is negative; ensure thyroid blockade for 131I-MIBG to prevent thyroid stunning; monitor for bone marrow suppression, nephrotoxicity, and hypertension; contraindicated in pregnancy; verify patient can follow radiation protection instructions (independent daily activities).

## Concrete Clinical Example
A 58‑year‑old with metastatic abdominal paraganglioma, hypertension, and elevated normetanephrine undergoes 123I-MIBG scintigraphy showing intense uptake in hepatic and osseous lesions; somatostatin receptor scan is negative. The skill selects 131I-MIBG therapy; after thyroid blockade, 6.8 GBq administered, resulting in 50% reduction in urinary metanephrines and improved blood pressure control.

**Source:** Japan Endocrine Society Clinical Practice Guideline for the Diagnosis and Management of Pheochromocytoma and Paraganglioma 2025, Japan Endocrine Society, 2025, doi:10.1507/endocrj.EJ25-0165