Plasma Metanephrines Yield Fewer False-Positive Results Than Urine Metanephrines in Patients With Obstructive Sleep Apnea

• Published in: The journal of clinical endocrinology and metabolism Vol. 109; no. 3; p. 844
• Main Authors: King, Thomas F J, Mok, Yingjuan, Dacay, Lily Mae, Wong, Hang Siang, Hsu, Pon Poh, Tan, Alvin, Wong, Kang Min, Saffari, Seyed Ehsan, Lenders, Jacques W M, Puar, Troy H
• Format: Journal Article
• Language: English
• Published: United States 20.02.2024
• Subjects: obstructive sleep apnea; pheochromocytoma; specificity; sensitivity; secondary hypertension; neuroendocrine tumors
• ISSN: 1945-7197
• DOI: 10.1210/clinem/dgad553

Obstructive sleep apnea (OSA) is associated with increased nocturnal sympathetic activity. In OSA patients, elevations in metanephrines may lead to false-positive tests when evaluating for pheochromocytoma or paraganglioma (PPGL). To evaluate whether morning plasma metanephrines would lead to fewer false-positive results than 24-hour urinary metanephrines in OSA patients. Patients undergoing polysomnography for suspected OSA were recruited. Plasma free and 24-hour urinary metanephrines were measured by HPLC-MS/MS. Patients with elevated levels had repeat measurements, abdominal imaging, and follow-up to diagnose or exclude a PPGL. Seventy-six patients completed polysomnography and biochemical testing; 68 (89.5%) patients had OSA, of whom 19 (27.9%) had elevated plasma and/or urinary metanephrines. On follow-up, one patient had a bladder paraganglioma, while PPGL was excluded in the remaining patients. OSA patients had more false-positive urinary metanephrines (17 of 67, 25.4%) than plasma metanephrines (2 of 67, 3.0%), P < .01, and this was more common in severe OSA (13 of 34, 38.2%), compared to moderate/mild OSA (4 of 33, 12.1%), P < .01. Both plasma and urinary metanephrines decreased after treatment with continuous positive airway pressure. On multivariable analysis, severe OSA, obesity, and family history of hypertension were positive predictors for false-positive urinary metanephrines in patients with suspected OSA. In OSA patients, plasma metanephrines are less likely to yield false-positive results for the diagnosis of PPGL than 24-hour urinary metanephrines. In patients with suspected OSA, obesity, or a family history of hypertension, plasma metanephrines may be the preferred first-line test to avoid unnecessary anxiety or follow-up.