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HelpOrder Code NMHR1 N-Methylhistamine, Random, Urine
Ordering Guidance
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 NMH24 / N-Methylhistamine, 24 Hour, Urine.
Specimen Required
Only orderable as part of a profile. For more information see NMHR / N-Methylhistamine, Random, Urine.
Patient Preparation: Patient must not be taking monoamine oxidase inhibitors (MAOI) or aminoguanidine as these medications increase N-methylhistamine (NMH) levels.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Container/Tube: Plastic, 5-mL tube
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Useful For
Screening for and monitoring of mastocytosis and disorders of systemic mast-cell activation, such as anaphylaxis and other forms of severe systemic allergic reactions as a part of a random urine collection profile
Monitoring therapeutic progress in conditions that are associated with secondary, localized, low-grade persistent, mast-cell proliferation and activation such as interstitial cystitis
Method Name
Only orderable as part of a profile. For more information see NMHR / N-Methylhistamine, Random, Urine.
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
N-Methylhistamine, RandomSpecimen Type
UrineSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 28 days |
| Ambient | 28 days | |
| Frozen | 28 days |
Reference Values
Only orderable as part of a profile. For more information see NMHR / N-Methylhistamine, Random, Urine.
0-5 years: 120-510 mcg/g creatinine
6-16 years: 70-330 mcg/g creatinine
>16 years: 30-200 mcg/g creatinine
Method Description
N-methylhistamine (NMH) is removed from urine using solid phase extraction. The eluate is analyzed using liquid chromatography/tandem mass spectrometry and quantified using a stable isotope labeled internal standard, d3-NMH. NMH and d3-NMH are detected in multiple reaction monitoring mode using the specific transitions for m/z 126 to m/z 109, and m/z 129 to m/z 112, respectively.(Unpublished Mayo Method)
Day(s) Performed
Monday, Wednesday, Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82542
Specimen Minimum Volume
3 mL