Ppgl Initial Screening Test Selection

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name: ppgl-initial-screening-test-selection
description: Selects the initial biochemical screening test for pheochromocytoma and paraganglioma based on test availability and clinical context. Triggers include patient presenting with palpitations, headaches, or hypertension; need to screen for PPGL in an incidentally discovered adrenal mass; or initial biochemical workup for suspected PPGL.
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# Initial PPGL Biochemical Screening Test Selection

## STEP 1 — Gather Information
Collect clinical triggers (symptoms, incidental adrenal mass), assess availability of random urinary fractionated metanephrines (creatinine-corrected), blood fractionated catecholamines, and plasma-free fractionated metanephrines; review medications and foods per Table 3 that may interfere; evaluate renal function for creatinine correction if urine test considered.  
→ Determine which test is feasible and appropriate for initial screening.

## STEP 2 — Rule In / Rule Out
Perform the selected initial screening test. If random urinary fractionated metanephrines (creatinine-corrected) >3× upper limit of normal, or blood fractionated catecholamines >3× upper limit, or plasma-free fractionated metanephrines > upper limit, then screen positive (rule in PPGL); otherwise screen negative (rule out PPGL).  
→ Proceed to classification based on screen result.

## STEP 3 — Classify or Stratify
If screen positive, proceed to confirmatory testing with 24-hour urinary fractionated metanephrines (or catecholamines) or plasma-free fractionated metanephrines per I-2-3; if screen negative but clinical suspicion remains high, repeat screening with an alternative sample type or consider clinical follow-up; if screen negative and low suspicion, consider alternative diagnoses.  
→ Decide on next diagnostic action.

## STEP 4 — Decide
For screen-positive patients, order confirmatory biochemical tests and arrange imaging per I-3; for screen-negative patients with low suspicion, discharge from PPGL workup; for screen-negative patients with high suspicion, repeat testing or seek specialist consultation.  
→ Initiate appropriate follow‑up pathway.

## Clinical Guardrails / Mimics / Pitfalls
Avoid testing during acute stress, after caffeine, nicotine, or tyramine‑rich foods; discontinue interfering medications (e.g., tricyclic antidepressants, decongestants) per Table 3; false positives common in critically ill or stressed patients; false negatives may occur with severe renal impairment affecting creatinine correction; plasma‑free fractionated metanephrines limited to one measurement under Japanese health insurance for differential diagnosis; ensure proper sample handling (fasting, supine rest 20–30 min, immediate freezing) to prevent degradation.

## Concrete Clinical Example
A 46‑year‑old woman presents with episodic palpitations and hypertension; an incidental 1.5 cm left adrenal nodule is found on abdominal CT. She reports no interfering medications and avoids caffeine. Random urinary fractionated metanephrines, corrected for creatinine, returns at 3.8× the upper limit of normal. Screening test is positive, prompting 24‑hour urinary fractionated metanephrines for confirmation.

**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