N-Methylhistamine, Random Urine

Abbrev Code:NMHR   
Order Code:LAB8221Order Name:N-Methylhistamine Random Urine
Methodology:Liquid chromatography/Tandem mass spectrometry (LC-MS/MS); Enzymatic colorimetric assay
CPT Codes: 82542 x1, 82570 x1
Turnaround Time:Specimens are sent to reference laboratory Mon-Fri; results are reported within 3-7 days.
Special Instructions:This test is for random urine collection only.  For timed urine see N-Methylhistamine, 24 hour Urine.

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.

This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared by the U.S. Food and Drug Administration.

Collection Instructions

Specimen:Urine, random
Optimal Volume:Submit entire collection; analysis requires 3 mL
Minimum\Peds Volume:3 mL
Container:Plastic leakproof container, sterile
Collection Instructions:Collect a random urine specimen within a few hours of symptom onset.
Patient Preparation:Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine as these medications increase N-methylhistamine (NMH) levels.
Causes for Rejection:Preserved urine; timed collection.

Processing and Shipping

Specimen Processing:Aliquot 5 mL, 3 mL minimum. Store refrigerated.
Shipping Instructions:Ship refrigerated.
Stability:28 days room temperature, refrigerated (preferred) and frozen.
Test Performed at or Referral Lab Lab Sendouts  (Mayo Medical Laboratories)
Referral Lab number:NMHR


Reference Range:

0-5 y

120-510 mcg/g creatinine

6-16 y

70-330 mcg/g creatinine

Greater than16 y

30-200 mcg/g creatinine



Use: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.

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