Clinics and Departments

Laboratory Services

Lab Dept:

Urine/Stool

Test Name:

METANEPHRINES FRACTIONATED, TIMED URINE

General Information

Lab Order Codes:

METP

Synonyms:

Metanephrines, Urine, 24 hour collection

CPT Codes:

83835 – Metanephrines

Test Includes:

Metanephrines Total 24 hr urine, Normetanephrines 24 hr urine, Metanephrine 24 hr urine, and Creatinine 24 hr urine

Logistics

Test Indications:

A first and second-order screening test for the presumptive diagnosis of catecholamine-secreting pheochromocytomas and paragangliomas.

Confirming positive plasma metanephrine results.

Lab Testing Sections:

Urine/Stool - Sendouts

Referred to:

Mayo Medical Laboratories (Test# 83006/METAF)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

2 days, test set up Monday - Saturday

Special Instructions:

See Patient Preparation

A 24 hour urine container with either 10 g (pediatric 3 g) boric acid or 25 mL (pediatric 15 mL) of 50% acetic acid should be obtained from the laboratory at the start of collection.

Submit an entire 24-hour urine collection. Refrigerate specimen during and after collection.

Note: Starting and ending times of collection are required for a timed urine collection and must be documented electronically or on the proper request form.

Specimen

Specimen Type:

Urine, timed

Container:

Plastic leakproof container with either 10 g (pediatric 3 g) boric acid or 25 mL (pediatric 15 mL) of 50% acetic acid should be obtained at the start of collection. Urine GUARD® collection container is preferred for a timed urine sample.

Draw Volume:

Submit an entire 24-hour urine collection

Processed Volume:

10 mL (Minimum: 2 mL) aliquot from a 24 hour urine collection

Collection:

For timed urine collections, empty the bladder, discard the voided sample, and note the start time. Collect all urine voided for the specified time period. At the end of the period, note the finishing time, add the last voided sample to the container by emptying the bladder. Bring the refrigerated container to the lab. Make sure all specimens submitted to the laboratory are properly labeled with the patient’s name, medical record number and date of birth.

Special Processing:

Lab Staff: Mix 24 hour urine with preservative well. Measure total volume and document. Remove 10 mL (Minimum: 5 mL) aliquot into a 13 mL urine tube. Store and ship specimen at refrigerated temperatures. Forward promptly.

Patient Preparation:

Tricyclic antidepressants (TCA), labeltalol, and sotalol medications may elevate levels of metanephrines producing results which 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.

Sample Rejection:

Specimens other than urine; mislabeled or unlabeled specimens

Interpretive

Reference Range:

Metanephrine (mcg/24 hrs)

Age

Males (mcg/24 hrs)

Females (mcg/24 hrs)

Normotensives

0 – 2 years:

Not established

Not established

3 – 8 years:

29 - 92

18 - 144

9 – 12 years:

59 - 188

43 - 122

13 – 17 years:

69 - 221

33 - 185

≥18 years:

44 - 261

30 – 180

Hypotensives

All ages:

<400

<400

Normetanephrine (mcg/24 hrs)

Age

Males (mcg/24 hrs)

Females (mcg/24 hrs)

Normotensives

0 – 2 years:

Not established

Not established

3 – 8 years:

34 – 169

29 – 145

9 – 12 years:

84 – 422

55 – 277

13 – 17 years:

91 – 456

57 – 286

18 – 29 years:

103 – 390

103 – 390

30 – 39 years:

111 – 419

111 – 419

40 – 49 years:

119 – 451

119 – 451

50 – 59 years:

128 – 484

128 – 484

60 – 69 years:

138 – 521

138 – 521

≥70 years:

148 – 560

148 – 560

Hypertensives

All ages:

<900

<900

Total Metanephrine (mcg/24 hrs)

Age

Males (mcg/24 hrs)

Females (mcg/24 hrs)

Normotensives

0 – 2 years:

Not established

Not established

3 – 8 years:

47 – 223

57 – 210

9 – 12 years:

201 – 528

107 – 394

13 – 17 years:

120 – 603

113 – 414

18 – 29 years:

190 – 583

142 – 510

30 – 39 years:

200 – 614

149 – 535

40 – 49 years:

211 – 646

156 – 561

50 – 59 years:

222 – 680

164 – 588

60 – 69 years:

233 – 716

171 – 616

≥70 years:

246 – 753

180 – 646

Hypertensives

All ages:

<1300

<1300

Interpretation: Increased metanephrine/normetanephrine levels are found in patients with pheochromocytoma and tumors derived from neural crest cells.

Total urine metanephrines ≤1300 mcg/24 hours can be detected in non-pheochromocytoma hypersensitive patients.

Further clinical investigation (e.g., radiographic studies) are warranted in patients whose total urinary metanephrine levels are >1300 mcg/24 hours (approximately 2 times the upper limit of normal). For patients with total urinary metanephrine levels of <1300 mcg/24 hours further investigations may also be indicated if either the normetanephrine or the metanephrine fraction of the total metanephrines exceed their respective upper limit for hypertensive patients. Finally repeat testing or further investigations may occasionally be indicated in patients with urinary metanephrine levels below the hypertensive cut-off, or even normal levels, if there is a very high clinical index of suspicion.

Critical Values:

N/A

Limitations:

See Patient Preparation

Significant physical stress (e.g. hypertensive stroke) may elevate levels of metanephrines.

This test utilizes a high-performance liquid chromatography/tandem mass spectrometry (LC-MS/MS) method and is not affected by the interfering substances that affected the previously utilized spectrophotometric (Pisano reaction) method (i.e., diatrizoate, chlorpromazine, hydrazine derivatives, imipramine, MAO inhibitors, methyldopa, phenacetin, ephedrine, or epinephrine).

This method is also not subject to the known interference of acetaminophen (seen with the plasma metanephrine high-performance liquid chromatography [HPLC]-EC method.)

Methodology:

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

References:

Mayo Medical Laboratories January 2013

Updates:

3/18/2004: Test moved from Specialty Laboratories to Mayo Medical Laboratories.
7/12/2010: Units update from ug/24 hours to mcg/24 hours.



  Lab Test Directory
    Chemistry
    Coagulation
    Flow/Immunology
    Hematology
    Microbiology/ Virology
    Other Fluids
    Pathology
    Serology
    Transfusion Services
    Urine/Stool

  Search Lab Test Directory
    List All Documents

  Lab Staff

  E-mail Lab Services