Home
HelpTest Code NMH1D N-Methylhistamine, 24 Hour, Urine
Reporting Name
N-Methylhistamine, 24 Hr, UPerforming Laboratory
Mayo Clinic Laboratories in Rochester
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 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 NMH24 / N-Methylhistamine, 24 Hour, Urine.
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Ordering Guidance
Random urine collection is preferred for patients with episodic symptoms, eg, in the context of allergic reactions, brought on by specific environmental factors; order NMHR / N-Methylhistamine, Random, Urine.
Specimen Required
Only orderable as part of a profile. For more information see NMH24 / N-Methylhistamine, 24 Hour, Urine.
Patient Preparation: Patient must not be taking monoamine oxidase inhibitors (MAOIs) 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 urine for 24 hours.
2. No preservative.
3. Aliquot into plastic tube and send at refrigerate temperature.
Specimen Type
UrineSpecimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
Only orderable as part of a profile. For more information see NMH24 / N-Methylhistamine, 24 Hour, Urine.
0-5 years: 120-510 mcg/g creatinine
6-16 years: 70-330 mcg/g creatinine
>16 years: 30-200 mcg/g creatinine
Interpretation
Increased concentrations of urinary N-methylhistamine (NMH) are consistent with urticaria pigmentosa (UP), systemic mastocytosis, or mast-cell activation. Because of its longer half-life, urinary NMH measurements have superior sensitivity and specificity than histamine, the parent compound. However, not all patients with systemic mastocytosis or anaphylaxis will exhibit concentrations outside the reference range and healthy individuals may occasionally exhibit values just above the upper limit of normal.
The extent of the observed increase in urinary NMH excretion is correlated with the magnitude of mast-cell proliferation and activation, UP patients, or patients with other localized mast-cell proliferation and activation, show usually only mild elevations, while systemic mastocytosis and anaphylaxis tend to be associated with more significant rises in NMH excretion (2-fold or more). There is, however, significant overlap in values between UP and systemic mastocytosis, and urinary NMH measurements should not be relied upon alone in distinguishing localized from systemic disease.
Up to 25% variability in random urine excreted levels may be observed, making 24-hour urine collections preferable for cases with borderline results.
Children have higher NMH levels than adults. By the age of 16 years, adult levels have been reached.
Day(s) Performed
Monday, Wednesday, Friday
Report Available
3 to 7 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| NMH1D | N-Methylhistamine, 24 Hr, U | 44340-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 605159 | N-Methylhistamine, 24 Hr | 44340-8 |