N-Methylhistamine, Urine

Test Code

CPT Codes


Preferred Specimen
5 mL of an unpreserved 24-hour urine collected in a leak-proof urine container

Minimum Volume
3 mL

Other Acceptable Specimens
Unpreserved random urine, or 24-hour urine in 30 mL 6N HCl, or 25 mL of 50% acetic acid, or 5g Na2CO3, or 10g boric acid

Collect 24 hour urine with no preservatives.

Total volume required. Record on both the specimen container and the request form.

Urine Preservative Collection Options:
Note: The addition of preservative or application oftemperature controls must occur within 4 hours of completion of the collection: 6N HCl, 50% Acetic Acid, Na(2)CO(3), Toluene, 6N HNO(3), Boric Acid, Thymol

Transport Temperature
Refrigerated (cold packs)

Specimen Stability
Room temperature: 24 hours
Refrigerated: 8 days
Frozen: 14 days

Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) • Enzymatic Colorimetric Assay

Setup Schedule
Set up: Tues, Thurs; Report available: 5 days

Reference Range
N-Methylhistamine, Urine
0-5 years 120-510 mcg/g creatinine
6-16 years 70-330 mcg/g creatinine
>16 years 30-200 mcg/g creatinine

Clinical Significance
Screening for and monitoring of mastocytosis and disorders of systemic mast-cell activation, such as anaphylaxis and other forms of severe systemic allergic reactions.

Monitoring therapeutic progress in conditions that are associated with secondary, localized, low-grade persistent, mast-cell proliferation and activation such as interstitial cystitis.

Performing Laboratory
Mayo Clinic Laboratories
200 First Street SW
Rochester, MN 55905

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.