| 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
