Metanephrines (Urine)

Testing Laboratory

Department

Chemical Pathology

Delphic Registration Code (Alpha Code)

METU

Test Code (Numeric Code)

3583

Laboratory Handling

Phlebotomy

Urine is collected into acid bottles (20mL of 6mol/L HCl)

Separating

Make aliquot for urine creatinine
Send primary sample to HPLC

Laboratory

LabPLUS High Performance Liquid Chromatography

Sample Stability

Must acidified within 48 hours of commencement of collection if the urine is not collected into acid bottles

Associated Tests

• Catecholamines (Urine)
• Metanephrines (Blood)

Synonyms

Metanephrine, Normetanephrine, 3-Methoxytyramine, 3MT

Turnaround Time

1 week

Specimen Type

• 24hr Urine
• Urine

Specimen Requirements

Tube/Container Type:

Preferred

• Acidified 24hr Urine Container
• BD Urine Tube (no additive)

Acceptable

• 24hr Urine Container
• BD Urine Tube (no additive)

Minimum Sample Volume (ml)

5

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• Specimen Container

Acceptable

• BD Urine Tube (no additive)

Minimum Sample Volume (ml)

2

Additional Specimen Information

Adult:

If measurement of catecholamines is also required on the same specimen, the 24h urine MUST be collected into a plastic 2L bottle containing acid (20mL of 6mol/L HCl).

Casual urine samples are not recommended for adults. Please register for QSCP and refer to the department.

Children:

Casual urines must be registered URGENTLY and given to Automation staff for acidifying WITHIN 2 HOURS of collection.
Acidify to a pH of 3 - 4

If a sample misses the 2 hour acidification window, please still acidify the sample immediately and record the time.

The analytical department will then make a decision on how to proceed. These samples should be registered for METU and QSCP to alert the department of the issue.

For casual collects on children at ACH the following protocol is used:

Once the sample is collected, send immediately to the laboratory. Please mark request form "Urgent" so that samples are treated with HCl as soon as possible.

Aliquot Instructions

Sample Type

• Urine

Transport to Lab

Ambient (8 - 24 degrees Celsius)
Chilled (2 - 8 degrees Celsius)
Frozen

Additional Referral/Aliquot Information

Please acidify before transporting to LabPlus.

Test Method

High performance liquid chromatography with electrochemical detection (HPLC-ECD)

Limitations / Interference

Effects of stress or acute illness
Metanephrines are metabolites of catecholamines, and their secretion is increased by stress e.g. acute illness, surgery, cardiac failure, stroke. Screening for phaeochromocytoma / paraganglioma should be delayed until the acute episode has settled.

Causes of false positives
Catecholamine rich diets including a diet containing pineapples, bananas, avocado, kiwi fruits, nuts or walnuts may increase casual urine metanephrine on average 2 times. This effect may last for 24 hours.
Levo‑dopa and dopamine infusion may significantly increase methoxytyramine, usually this rise is greater than 10 times the upper reference limit.
As with metanephrine and normetanephrine, significant illness may also increase the levels of methoxytyramine to 2–4 times upper reference limit.

Uncertainty of Measurement

Metanephrine 12% Normetanephrine 12%

Billing Code

3583

The best tests for diagnosing phaeochromocytoma are:

1. Urine metanephrines (24h urine for adults)

2. Plasma metanephrines (5mL EDTA blood)

Urine and plasma metanephrines have superior diagnostic performance to urine catecholamines.

Notes:

1. This test is not intended for the detection of neuroblastoma in children. Urine metanephrines are only recommended for children with hypertension.

2. Metanephrines are increased by stress e.g. acute illness, heart failure, stroke. Screening for phaeochromocytoma should be delayed until the acute illness has settled, unless the findings will have a clear impact on acute management (caution is needed in interpretation).

Contact Information