From the Research
The optimal range for normetanephrines in females is typically 0-148 pg/mL when measured in plasma, as marked elevations above this level may indicate conditions such as pheochromocytoma or paraganglioma 1. This reference range may vary slightly between different laboratories, but generally, values below 148 pg/mL are considered normal for adult females.
- Normetanephrine is a metabolite of norepinephrine, a stress hormone produced by the adrenal glands.
- Elevated levels of normetanephrine can indicate conditions such as pheochromocytoma (a rare adrenal tumor), neuroblastoma, or other catecholamine-producing tumors. When interpreting normetanephrine results, it's essential to consider that certain factors can temporarily increase levels, including:
- Stress
- Strenuous exercise
- Certain medications (such as tricyclic antidepressants, MAO inhibitors, and some decongestants)
- Caffeine consumption
- Alcohol withdrawal For accurate results, patients should avoid these potential interferents before testing when possible. If levels are elevated, repeat testing or additional diagnostic procedures may be recommended to confirm findings before making clinical decisions, as marked metanephrine elevations (> 3 times the upper limit of normal [ULN]) are highly suggestive of pheochromocytoma or paraganglioma 1. The diagnostic utility of ratios to creatinine of 'spot' urinary metanephrines has been compared with 24-h-urinary and plasma results in phaeochromocytomas and paragangliomas, and the results suggest that spot urine collection may facilitate diagnosis and follow-up of these conditions through improved patient compliance 2. However, the optimal range for normetanephrines in females is best supported by the most recent study, which suggests a normal range of 0-148 pg/mL 1.