Pheo Screening Strategy

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name: pheo-screening-strategy
description: First-line screening logic to identify patients who require biochemical testing for Pheochromocytoma or Paraganglioma. Trigger when a clinician asks "who to screen for pheo", "evaluation of adrenal incidentaloma", or "workup for paroxysmal hypertension."
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# Pheochromocytoma Screening Strategy

This skill provides the clinical decision criteria for initiating biochemical screening for pheochromocytoma and paraganglioma based on the Endocrine Society Clinical Practice Guidelines.

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## Step 1 — Identification of High-Risk Clinical Features

Screen for pheochromocytoma if **any** of the following are present:

1. **Paroxysmal Symptoms ("The Spell"):**
   - Triad of: Episodic headache, sweating, and palpitations.
   - Note: The presence of all three in a hypertensive patient has high specificity (>90%).

2. **Refractory or Early-Onset Hypertension:**
   - Drug-resistant hypertension (uncontrolled on ≥3 agents).
   - Marked blood glucose lability or paradoxically worsening BP with beta-blockers.
   - Hypertension onset at age <20 years.

3. **Adrenal Incidentaloma:**
   - Any adrenal mass discovered on imaging, especially if the unenhanced CT attenuation is >10 Hounsfield Units (HU).

4. **Genetic Predisposition:**
   - Personal or family history of MEN2, NF1, or von Hippel-Lindau (VHL).
   - Personal history of a previous glomus tumor or paraganglioma.

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## Step 2 — Decision: To Screen or Not to Screen?

| Finding Present? | Action |
|---|---|
| **YES** to any above | Move to **Biochemical Testing** (Plasma or 24h Urinary Metanephrines). |
| **NO** | Pheochromocytoma is unlikely; manage as primary hypertension unless other secondary features emerge. |

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## Clinical Guardrails

- **Do NOT proceed to imaging first.** Always obtain biochemical proof before ordering CT or MRI. Imaging first leads to false positives and unnecessary surgeries.
- **Beta-Blocker Warning:** Never start a beta-blocker (e.g., Propranolol, Atenolol) before establishing alpha-blockade if pheo is suspected, as this can trigger a hypertensive crisis due to unopposed alpha-stimulation.
- **Medication Interference:** Many drugs (TCAs, Levodopa, Decongestants) can cause false-positive metanephrine elevations. Review the med list before testing.

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**Source:** Lenders JW, et al. Pheochromocytoma and Paraganglioma: An Endocrine Society Clinical Practice Guideline. *J Clin Endocrinol Metab*. 2014;99(6):1915-42. doi: 10.1210/jc.2014-1498