Ordering Recommendation

Aid in evaluation of patient with allergic signs and symptoms, such as anaphylaxis and other forms of severe systemic allergic reactions. May assist when diagnosing and monitoring mast-cell activation disorders or when evaluating histamine production over a longer time frame. Patients with chronic mast-cell activation often have chronically elevated N-methylhistamine (NMH) levels and will sometimes have intermittent NMH elevations. In these cases, N-Methylhistamine, 24-Hour Urine (2011034) is preferred.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine as these medications increase N-methylhistamine (NMH) levels. Specimen should be collected within a few hours of symptom onset.



Specimen Preparation

Transfer 5 mL urine to ARUP Standard Transport Tubes. (Min: 3 mL)
Test is not performed at ARUP; separate specimens must be submitted when multiple tests are ordered.

Storage/Transport Temperature

Refrigerated. Also acceptable: Room temperature and frozen.

Unacceptable Conditions

Ambient: 2 weeks; Refrigerated: 28 days; Frozen: 28 days


Quantitative Liquid Chromatography-Tandem Mass Spectrometry/Colorimetry




3-10 days

Reference Interval

By Report

Interpretive Data

Compliance Category

Performed by non-ARUP Laboratory


Hotline History


CPT Codes

82542, 82570


Component Test Code* Component Chart Name LOINC
3002744 N-Methylhistamine, Random Urine 13781-0
3002745 Creatinine Concentration, Random Urine 2161-8
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • 1-Methylhistamine
  • Histamine Metabolites
  • Urinary N-Methylhistamine
N-Methylhistamine, Random Urine

Mayo Clinic Laboratories