Hot Flushes and Migraines Do Not Cause Elevated Metanephrines
Hot flushes and migraines themselves do not cause elevated plasma or urinary metanephrine levels. However, certain migraine medications—specifically triptans like eletriptan—can cause false-positive elevations in urinary metanephrines, which is a critical pitfall to recognize when interpreting these tests.
Key Evidence on Medication Interference
Triptans and False Positives
A case report demonstrated that eletriptan (a triptan used for migraine treatment) caused markedly elevated urinary metanephrines (2,494 μg; normal 45-290 μg) and normetanephrines (1,341 μg; normal 82-500 μg), while plasma metanephrines remained normal or only mildly elevated 1. Within one week of discontinuing eletriptan, both urine and plasma levels completely normalized. This discrepancy between plasma and urine studies strongly suggests assay interference rather than true catecholamine excess.
Other Medications That Interfere
The Endocrine Society guidelines explicitly warn that medications interfering with catecholamine disposition (such as tricyclic antidepressants) and those directly interfering with measurement methods (acetaminophen, mesalamine, sulfasalazine) can result in mildly to markedly raised metanephrine values 2. More recent evidence confirms that norepinephrine reuptake blockers (NRBs), antipsychotics, and nicotine use can independently elevate plasma free normetanephrine and methoxytyramine concentrations in a dose-dependent manner 3.
Physiological Stress vs. Disease States
The guidelines note that physiological stress associated with extreme illness (such as intensive care settings) can cause marked elevations of plasma or urine metanephrines 2. However, this refers to severe systemic illness, not the physiological stress of hot flushes or migraines themselves.
Importantly, chronic cardiometabolic comorbidities and chronic illness do not significantly interfere with plasma free metanephrine measurements—false-positive elevations remain rare (only 7% in patients without pheochromocytoma) when medications are accounted for 3.
Clinical Approach to Suspected False Positives
When to Suspect Medication Interference:
- Discordance between plasma and urine metanephrines (elevated urine with normal/mildly elevated plasma)
- Patient taking triptans, tricyclic antidepressants, NRBs, antipsychotics, or other interfering medications
- Borderline elevations without typical pheochromocytoma symptoms
Recommended Testing Strategy:
- Obtain plasma metanephrines with proper collection technique: Patient supine for at least 30 minutes before blood draw 2
- If elevated, discontinue interfering medications (when medically safe) and retest after appropriate washout period
- For persistent borderline elevations of normetanephrine, consider clonidine suppression testing (97% sensitivity, 100% specificity) 2
- In low-probability cases with borderline results, a wait-and-retest approach over 6+ months can identify enlarging tumors through progressive increases 2
Critical Pitfalls to Avoid
- Do not assume hot flushes or migraines themselves elevate metanephrines—they don't
- Always review the medication list before interpreting metanephrine results, particularly for triptans in migraine patients
- Recognize that seated blood draws increase false-positive rates due to sympathetic activation; supine positioning is essential 2
- Plasma metanephrines are more reliable than urinary measurements when medication interference is suspected, as demonstrated by the eletriptan case 1
The bottom line: If a patient with migraines on triptans has elevated metanephrines, stop the triptan and retest before pursuing extensive pheochromocytoma workup.