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Falsely elevated plasma metanephrine in patients taking midodrine
Holly Emms1, George Farah1, Brian Shine2
11 Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
Annals of Clinical Biochemistry
|January 24, 2018
Summary
Patients taking midodrine may experience falsely high plasma metanephrine levels. This is due to analytical interference from the drug, potentially mimicking phaeochromocytoma or paraganglioma.
Area of Science:
- Clinical Biochemistry
- Pharmacology
- Endocrinology
Background:
- Plasma metanephrines are the primary diagnostic test for phaeochromocytomas and paragangliomas.
- Accurate biochemical testing is crucial for diagnosing these rare neuroendocrine tumors.
Observation:
- Two patients on midodrine, a treatment for severe postural hypotension, presented with significantly elevated plasma metanephrines.
- These elevations were observed in the absence of confirmed phaeochromocytoma or paraganglioma.
Findings:
- Midodrine or its metabolite, desglymidodrine, interferes with plasma metanephrine assays.
- High-performance liquid chromatography tandem mass spectrometry confirmed co-elution of desglymidodrine with metanephrine.
- Discontinuation of midodrine normalized plasma metanephrine concentrations.
Implications:
- Midodrine use can lead to false-positive results in plasma metanephrine testing.
- Clinicians must consider midodrine interference when interpreting elevated plasma metanephrines.
- Awareness of this drug interaction is vital to prevent misdiagnosis of phaeochromocytoma and paraganglioma.
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