Ata Ppgl Confirmatory Test Selection

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name: ata-ppgl-confirmatory-test-selection
description: Selects the appropriate confirmatory test after a positive pheochromocytoma/paraganglioma (PPGL) screening test. Triggers include elevated random urinary metanephrines (>3× ULN after creatinine correction), blood catecholamines (>3× ULN), or plasma-free fractionated metanephrines (>ULN).
---

# Select confirmatory test after positive PPGL screen

## STEP 1 — Gather Information
Collect which screening test was positive (random urinary fractionated metanephrines corrected for creatinine, blood fractionated catecholamines, or plasma-free fractionated metanephrines), the measured value, renal function (eGFR), and the patient’s ability to complete a 24‑hour urine collection.

## STEP 2 — Rule In / Rule Out
If the patient cannot reliably perform a 24‑hour urine collection (e.g., incontinence, eGFR <30 mL/min/1.73 m²) → rule out urine‑based confirmatory tests and select plasma‑free fractionated metanephrines. Otherwise, proceed.

## STEP 3 — Classify or Stratify
Match the analyte of the positive screening test to its confirmatory test: random urinary metanephrines → 24‑hour urinary fractionated metanephrines; blood catecholamines → 24‑hour urinary fractionated catecholamines; plasma‑free metanephrines → plasma‑free fractionated metanephrines.

## STEP 4 — Decide
Order the selected confirmatory test using the diagnostic cutoff: >3× ULN for urinary metanephrines, >2× ULN for urinary catecholamines, >ULN for plasma‑free metanephrines.

## Clinical Guardrails / Mimics / Pitfalls
Do not use plasma‑free fractionated metanephrines if the sample is not kept cold and separated within 30 minutes; avoid urine tests when creatinine correction is unreliable (e.g., low muscle mass, amputations); do not rely on random urine for confirmation due to high false‑positive rate.

## Concrete Clinical Example
A 52‑year‑old with episodic headaches and hypertension had a random urinary metanephrines level 4.2× ULN after creatinine correction. The patient has normal renal function (eGFR 78) and can collect urine. The confirmatory test ordered is 24‑hour urinary fractionated metanephrines.

**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 ata-ppgl-confirmatory-test-selection calculator