N-Methylhistamine, Random, Urine

Message

Sendout, Mayo test code: NMHR

Test Code

LAB234002

Alias/See Also

1-Methylhistamine
Histamine Metabolites
Urinary N-Methylhistamine
NMHR
NMH
N-Methylhistamine

CPT Codes
82542, 82570

Preferred Specimen

5 mL random urine collection

Patient Preparation
Patient must not be taking monoamine oxidase inhibitors (MAOI) 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.

Transport Container

Plastic vial

Transport Temperature

Refrigerated

Specimen Stability

Refrigerated (preferred): 28 days
Frozen: 28 days
Ambient: 14 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Methodology
NMHR1: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) CRETR: Enzymatic Colorimetric Assay

FDA Status
Approved

Setup Schedule

Tuesday, Thursday

Report Available

3-7 days

Limitations

While an average North American diet has no effect on urinary N-methylhistamine (NMH) levels, mild elevations (around 30%) may be observed on very histamine-rich diets. This problem is more pronounced if random-urine specimens are used and collected following a histamine-rich meal.

NMH levels may be depressed in individuals who have an alteration in the histamine-N-methyltransferase gene (HNMT), which encodes the enzyme that catalyzes NMH formation. This alteration results in an amino acid change that decreases the rate of NMH synthesis.

When N-acetylcysteine is administered at levels sufficient to act as an antidote for the treatment of acetaminophen overdose, it may lead to falsely decreased creatinine results.

Reference Range

Included with 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 Clinic Laboratories, Rochester, Minnesota

Additional Information
N-Methylhistamine, Random, Urine

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.