Ppgl Asymptomatic Carrier Surveillance Frequency

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name: ppgl-asymptomatic-carrier-surveillance-frequency
description: Establishes surveillance frequency for asymptomatic genetic carriers of PPGL pathogenic variants after an initial negative genetic screen. It guides clinicians in determining long-term monitoring plans and follow-up schedules for PPGL mutation carriers, recommending annual clinical evaluation, biennial fractionated metanephrines evaluation, and triennial MRI of head/neck/chest/abdomen/pelvis.
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# Asymptomatic Genetic Carrier Surveillance Frequency Determination for PPGL

## STEP 1 — Gather Information
Collect genetic test result confirming a pathogenic PPGL variant, personal and family history of PPGL or related syndromes, baseline clinical assessment (symptoms, blood pressure, heart rate), baseline fractionated metanephrines in 24‑hour urine (creatinine‑corrected), and baseline MRI of the head, neck, chest, abdomen, and pelvis.

## STEP 2 — Rule In / Rule Out
Is a pathogenic PPGL germline variant identified? If **yes**, proceed to surveillance planning; if **no**, consider alternative explanations or routine population screening and discontinue carrier‑specific surveillance.

## STEP 3 — Classify or Stratify
Stratify by gene class: SDHx pathogenic variant (SDHA, SDHB, SDHC, SDHD) versus other hereditary PPGL genes (RET, VHL, NF1, etc.), as surveillance specifics differ per guideline.

## STEP 4 — Decide
For SDHx carriers: initiate lifelong annual clinical evaluation, biennial fractionated metanephrines measurement, and triennial MRI of head/neck/chest/abdomen/pelvis. For RET, VHL, or NF1 carriers: follow the syndrome‑specific surveillance recommendations outlined in the respective guidelines.

## Clinical Guardrails / Mimics / Pitfalls
Do not rely on clinical evaluation alone; biochemical and imaging components are essential. Do not discontinue surveillance after a single negative test when a pathogenic variant is present. Avoid repeated plasma‑free fractionated metanephrines testing beyond once due to Japanese insurance restrictions. Prioritize MRI over CT for frequent surveillance to limit radiation exposure, especially in young carriers. Remember that SDHD carriers have a high risk of nonfunctional head‑and‑neck PGLs, so head‑and‑neck MRI is mandatory.

## Concrete Clinical Example
A 28‑year‑old woman with a known SDHB pathogenic variant has normal catecholamines and a negative neck‑to‑pelvis MRI. She undergoes annual clinical review, fractionated metanephrines every 2 years, and whole‑body MRI every 2–3 years; at age 32 her MRI reveals a 6 mm adrenal nodule, prompting biochemical re‑testing and early surgical consultation.

**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
> **TODO:** consider adding scripts/calc.py for the ppgl-asymptomatic-carrier-surveillance-frequency calculator