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    Eletriptan use may cause falsely elevated urine metanephrine and normetanephrine levels, mimicking pheochromocytoma. Discontinuation of eletriptan led to normalization of these levels, suggesting a drug-induced effect.

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    Area of Science:

    • Biochemistry
    • Endocrinology
    • Pharmacology

    Background:

    • Pheochromocytoma diagnosis relies on detecting excess catecholamines and metabolites.
    • Biochemical tests can yield false positives due to medication side effects.

    Observation:

    • A patient on eletriptan for migraines presented with severely elevated urinary metanephrines and normetanephrines.
    • Plasma levels were only mildly elevated, and adrenal imaging was normal.

    Findings:

    • Urine metanephrine levels were 2,494 μg (normal: 45-290 μg) and normetanephrine levels were 1,341 μg (normal: 82-500 μg).
    • Plasma metanephrines were 27 pg/mL (normal: 0-62 pg/mL) and normetanephrines were 255 pg/mL (normal: 0-145 pg/mL).
    • Within a week of discontinuing eletriptan, all metanephrine and normetanephrine levels normalized.

    Implications:

    • Eletriptan may cause false-positive urine metanephrine and normetanephrine tests.
    • This highlights the importance of considering drug effects in biochemical testing for pheochromocytoma.
    • Further research is needed to clarify the mechanism of eletriptan's effect on urine assays.