Metanephrines Total
Label Mnemonic: MET24
Epic Lab Code: LAB7451
Downtime Form: A-1a General Laboratory Requisition
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
24 hr Urine More information
Specimen Instructions:
Refrigerate during 24 hr collection in plastic container. Adequate refrigeration is the most important aspect of specimen preservation.

Abstain from medications for 72 hours prior to collection.
Collection Medium:
Urine - 24 hour/timed plastic urine container
Minimum:
Preferred Minimum: 4 mL of a well-mixed urine from 24 hour collection. Random urine is also accepted at reference lab. Refrigerate during collection and submission.

Absolute Minimum: 2.5 mL of a well-mixed urine from 24 hour collection. Random urine is also accepted at reference lab. Refrigerate during collection and submission.
Rejection Criteria:
Room temperature specimens.
Turn Around Time:
1-4 days upon receipt at reference laboratory.
Reference Range:
Reference Intervals for 24 Hour Calculations (24-Hour Urine)

Components             Reference Interval

Metanephrine
  Male
    0-6 years            Not Established 
    7-12 years           45-179 μg/d 
    13-17 years          61-202 μg/d 
    18 years and older   62-207 μg/d 

  Female
    0-6 years            Not Established 
    7-17 years           42-135 μg/d 
    18 years and older   39-143 μg/d 

Normetanephrine
  Male
    0-6 years            Not Established 
    7-12 years           70-273 μg/d 
    13-17 years          92-312 μg/d 
    18-29 years          95-379 μg/d 
    30 years and older   125-510 μg/d 

  Female
    0-6 years            Not Established 
    7-12 years           52-247 μg/d 
    13-17 years          73-266 μg/d 
    18 years and older   109-393 μg/d 

Creatinine (24 hr)
  Male
    3-8 years            140-700 mg/d
    9-12 years           300-1300 mg/d
    13-17 years          500-2300 mg/d
    18-50 years          1000-2500 mg/d
    51-80 years          800-2100 mg/d
    81 years and older   600-2000 mg/d

  Female
    3-8 years            140-700 mg/d
    9-12 years           300-1300 mg/d
    13-17 years          400-1600 mg/d
    18-50 years          700-1600 mg/d
    51-80 years          500-1400 mg/d
    81 years and older   400-1300 mg/d
Interpretive Data:
The optimal specimen for this testing is a 24-hour urine collection. Per-day calculations are not reported for patients younger than 18 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. 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 700 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.
Comments:
If screening for Neuroblastoma, the following tests are suggested: CAT24 (Catecholamines, Fractionated; Dopamine is included), HVA24 (Homovanillic Acid), VMA24 (Vanillylmandelic Acid).

Secreting neuroendocrine tumors typically are associated with metanephrine or normetanephrine concentrations several times higher than the upper reference intervals. Other reasons for elevated concentrations include intense physical activity, life-threatening illness, and drug interferences. Essential hypertension is often associated with slight elevations (metanephrine less than 3500 nmol/day and normetanephrine less than 4900 nmol/day). Other reasons for slight and moderate elevations include emotional and physical stress and improper specimen collection.
Methodology:
Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry
CPT Code:
83835
 
See also:
Catecholamines, Fractionated, 24 hr Urine
Homovanillic Acid, 24 hr Urine
Vanillylmandelic Acid, 24 hr Urine