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N-Methylhistamine, Urine, 24-hour
MessageSendout, Mayo test code: NMH24
Test Code
LAB5210322
Alias/See Also
1-Methylhistamine
Histamine Metabolites
Urinary N-Methylhistamine
NMH24
Histamine Metabolites
Urinary N-Methylhistamine
NMH24
CPT Codes
82542
Preferred Specimen
5 mL urine collected from a 24-hour urine container.
Minimum Volume
3 mL
Other Acceptable Specimens
URINE PRESERVATIVE COLLECTION OPTIONS
Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.
| Ambient | OK |
| Refrigerate | Preferred |
| Frozen | OK |
| 50% Acetic Acid | OK |
| Boric Acid | OK |
| Diazolidinyl Urea | No |
| 6M Hydrochloric Acid | OK |
| 6M Nitric Acid | OK |
| Sodium Carbonate | OK |
| Thymol | No |
| Toluene | No |
Instructions
1. Collect urine for 24 hours.
2. No preservative.
3. Aliquot into plastic tube and send at refrigerate temperature.
2. No preservative.
3. Aliquot into plastic tube and send at refrigerate temperature.
Transport Container
Plastic, 5-mL tube
Transport Temperature
Refrigerated
Specimen Stability
Refrigerated (preferred): 28 days
Frozen: 28 days
Ambient: 14 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
NMH1D: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) CRT24: 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.
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 24-hour urine collection specimens
Monitoring therapeutic progress in conditions that are associated with secondary, localized, low-grade persistent, mast-cell proliferation and activation such as interstitial cystitis
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, 24 Hour, Urine
