Metanephrines, Urine 24 Hr
This is a useful test to determine the cause of persistent hypertension. The urine sample is slightly more accurate, since having blood taken can cause the hormones and metabolites to increase.
Metanephrine is a metabolite of adrenaline (one of the hormones produced by the adrenal glands- these hormones are known as catecholamines). By measuring its levels, doctors can get a clear picture of the activity of the catecholamines in the body. Catecholamines are a group of hormones that are released into the blood in times of stress. The most common catecholamines are norepinephrine and epinephrine. These are produced by the adrenal glands and cells of the sympathetic nervous system. The metabolites of these hormones can be measured in the urine. Measuring metabolites in the urine is used to determine adrenal functions since rare disorders like pheochromocytomas can cause these hormone levels to be abnormal. Therefore, this is a useful test to determine the cause of persistent hypertension. The urine sample is slightly more accurate than a blood sample, since having blood taken can cause these hormones and metabolites to increase.
This test is performed in following conditions such as:
• Persistent high blood pressure
• High blood pressure that does not respond to treatment
• Severe headaches
• Sweating and flushing
• Rapid heart rate
No caffeine before or during collection. Avoid tobacco, tea, coffee, for three days prior to specimen collection. It is preferable to be off medications for three days prior to collection. Common antihypertensives (diuretics, ACE inhibitors, calcium channel blockers, alpha and beta blockers) cause minimal or no interference. Medications which are alpha agonists (Aldomet), alpha blockers (Dibenzyline) should be avoided 18-24 hours prior to specimen collection. Monamine oxidase inhibitors should be discontinued at least one week prior to beginning collection. The person being tested should void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Refrigerate specimen before returning it to the lab.
Estimated Time Taken
Turnaround for this test is typically 8-10 business days.