Properly Collected Plasma Metanephrines Excludes PPGL After False-Positive Screening Tests
Gregory A Kline1, Jessica Boyd2,3, Brenda Polzin4
1Cumming School of Medicine, Department of Medicine, University of Calgary, Calgary, Canada.
The Journal of Clinical Endocrinology and Metabolism
|April 13, 2021
Summary
False-positive screening for pheochromocytoma/paraganglioma (PPGL) is common. Properly collected plasma metanephrines significantly reduce false positives compared to urine tests.
Area of Science:
- Endocrinology
- Clinical Chemistry
- Diagnostic Testing
Background:
- Screening for pheochromocytoma/paraganglioma (PPGL) often yields false-positive results.
- Real-world screening practices may contribute to inaccurate diagnostic interpretations.
Purpose of the Study:
- To assess the correlation between urine and seated plasma metanephrines in outpatients without PPGL.
- To compare these results with meticulously prepared, supine-collected plasma metanephrines.
Main Methods:
- Retrospective cohort study analyzing laboratory and registry data (2012-2018).
- Compared paired urine and plasma metanephrine tests (<90 days apart) in outpatients.
- Evaluated meticulously prepared, supine-collected plasma metanephrines against age-adjusted references.
Main Results:
- A poor-to-moderate correlation (r=0.33-0.50) was found between urine and seated plasma metanephrines.
- 19.2% of outpatients with high urine metanephrines also had high seated plasma metanephrines, despite absence of PPGL.
- Meticulously prepared, supine-collected plasma metanephrines showed a false-positive rate of <3% in patients without PPGL or adrenal mass.
Conclusions:
- Standard urine and seated plasma metanephrine tests show poor correlation and high false-positive rates for PPGL screening.
- Properly prepared and supine-collected plasma metanephrines significantly improve diagnostic accuracy and reduce false positives.
- Optimized sample collection protocols are crucial for reliable PPGL diagnosis.
