Metanephrines, 24-Hour Urine

Metanephrines, 24-Hour Urine

Alternate Test Name

Metanephrines, Fractionated, 24 Hour Urine

Epic Mnemonic
Sunquest Mnemonic

LAB409
UMETNB

Category

Sendouts

Methodology

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Stable Isotope Dilution Analysis

Test Performance Schedule

Monday - Friday

Result Availability

3 – 5 days

Container

24-hour urine container, no preservative
Note: Additionof 50% acetic acid or 10 g boric acid prior to start of collection is preferred but not required. Refrigeration during and after urine collection is an acceptable means of urine preservation.
• If adding preservative:
• Add 25 mL 50% acetic acid or 10 g boric acid at start of collection
• Children under 5 years, add 15 mL 50% acetic acid or 3 g boric acid

Volume

Pref. Vol.: 10.0 mL from mixed entire 24 hour collection
Min. Vol.: 2.0 mL from mixed entire 24 hour collection

Collection Instructions

• To begin collection, have patient urinate, noting the date and exact time
• Discard the first portion of urine, but document date and time of voiding on the container label and test requisition as the “start” of the timed specimen
• Save all urine voided during the designated time period (usually 24 hours), including the portion voided at exact end of time period
• Document date and time of final voiding on the label and requisition as the “end” of the timed specimen
• Refrigerate during and after collection

Transportation Instructions

Refrigerate during and after collection

Stability

• Room Temperature: 7 days
• Refrigerated (preferred): 7 days
• Frozen: 14 days

Causes for Rejection

Specimens preserved with boric acid or acetic acid

Remarks

Patient Preparation:
Tricyclic antidepressants, labetalol, and sotalol medications may elevate levels of metanephrines producing results that cannot be interpreted. If clinically feasible, it is optimal to discontinue these medications at least 1 week before collection. For advice on assessing the risk of removing patients from these medications and alternatives, you may consider consultation with a specialist in endocrinology or hypertension.

Test includes:
• Metanephrine
• Normetanephrine
• Total Metanephrine

CPT Codes

83835

Effective/Revised

11/20/2019

The optimal specimen for this testing is a 24-hour urine collection. Per-day calculations are not reported for patients younger than 7 years of age and for the following specimen types: a random collection, a collection with duration of less than 20 hours, a collection with duration of greater than 28 hours, or a collection with total volume less than 400 mL (if 18 years of age or older) or greater than 5000 mL (all ages). Ratios to creatinine may be useful for these evaluations.

Smaller increases in metanephrine and/or normetanephrine concentrations (less than two times the upper reference limit) usually are the result of physiological stimuli, drugs, or improper specimen collection. Essential hypertension is often associated with slight elevations (metanephrine less than 400 µg/d and normetanephrine less than 900 µg/d). Elevated concentrations may be due to intense physical activity, life-threatening illness, and drug interferences.
Significant elevation of one or both metanephrines (three or more times the upper reference limit) is associated with an increased probability of a neuroendocrine tumor.