N-Methylhistamine, Random, Urine

Test Code

NMHR

Quest Code

39604

Includes

Creatinine

Preferred Specimen

5 mL urine collected in a sterile, screw-cap container with no preservative

Patient Preparation
Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine as these medications increase N-methylhistamine (NMH) levels.

Minimum Volume

3 mL

Instructions

1. Collect a random urine specimen within a few hours of symptom onset.
2. No preservative

Advisory Information: Patients with chronic mast cell activation often have chronically elevated N-methylhistamine (NMH) levels and will sometimes have intermittent NMH elevations. In these cases, a 24-hour urine collection is preferred. See 39559-N-Methylhistamine, 24 Hour, Urine.

Transport Container

Plastic urine container

Transport Temperature

Frozen

Specimen Stability

Room temperature: 14 days
Refrigerated: 28 days
Frozen: 28 days

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

Reference Range

N-Methylhistamine, Random, Urine

0-5 years	120-510 mcg/g Cr
6-16 years	70-330 mcg/g Cr
>16 years	30-200 mcg/g Cr

Creatinine, Random, Urine	See Laboratory Report

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 using random urine specimens.

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 Clinical Laboratories

200 1st Street SW

Rochester, MN 55905-0001

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.