Preparation of the patient for the analysis of metanephrines in 24-hour urine

Quantitative determination of metanephrines (metanephrine, normetanephrine, and 3-methoxytyramine) in urine is performed using high-performance liquid chromatography (HPLC) with electrochemical detection, a technique that is the gold standard in laboratory diagnostics. This technique enables accurate and reliable chromatographic quantification of all three parameters from a single sample.

Patient Preparation

Two to three days prior to urine collection, avoid consuming: coffee, cocoa, tea, cola, bananas, and citrus fruits, products containing vanilla, chocolate, hazelnuts, kiwi, and avocado. Five days before urine collection, it is preferable to discontinue therapy with medications containing adrenaline or similar compounds: dopamine, methyldopa (Aldomet, Aldoril, Dopegit, Dopamet), nasal drops, bronchodilators, cough syrups, ACE inhibitors, calcium antagonists, MAO inhibitors, phenothiazines, antidepressants, alpha1 and beta2 antagonists, labetalol, nitroglycerin, theophylline, and Na-nitroprusside.

• The urine collection bottle can be obtained at the BioDiagnostica reception desk or you can prepare yourself a dark bottle with a volume of 1.5-2 liters.
• Pour the preservative into the bottle (10-15 ml of 25% HCl).
• Consult laboratory staff for the preservative!
• Discard the first morning urine. Collect each subsequent urine during the day and night in the bottle. Also, pour the first morning urine of the next day into the bottle to complete the urine collection.
• Record the start and end times of urine collection. During collection, keep the bottle with preservative cold (4-8 °C).
• Bring the collected urine to the laboratory as soon as possible.
• If possible, measure the volume of collected urine, record the value, pour a portion of 50-100 ml and bring it to the laboratory.
• If it is not possible to accurately measure the volume of collected urine, bring the entire amount to the laboratory. The preserved urine sample can be stored for up to 5 days at temperatures of 2-8 °C.
• For longer periods, the sample is stored at -20 °C.
• If it is difficult or not possible to collect a 24-hour urine sample, “spontaneous” urine samples can be analyzed, and in that case, the results are expressed relative to the concentration of creatinine in the urine.