Home
HelpOrder Code NMH24 N-Methylhistamine, 24 Hour, Urine
Ordering Guidance
Random urine collections are 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.
If the total volume provided is less than 300 mL, this test will be canceled and NMHR ordered and performed.
Necessary Information
Specimen volume (in milliliters) and duration are required.
Specimen Required
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.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
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 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
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| NMH1D | N-Methylhistamine, 24 Hr, U | No | Yes |
| CRT24 | Creatinine, 24 HR, U | No | Yes |
Special Instructions
Method Name
NMH1D: Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
CRT24: Enzymatic Colorimetric Assay
Reporting Name
N-Methylhistamine, 24 Hr, USpecimen Type
UrineSpecimen Minimum Volume
1.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 14 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
N-METHYLHISTAMINE
0-5 years: 120-510 mcg/g creatinine
6-16 years: 70-330 mcg/g creatinine
>16 years: 30-200 mcg/g creatinine
CREATININE
Males: 930-2955 mg/24 hours
Females: 603-1783 mg/24 hours
Reference values have not been established for patients who are younger than 18 years.
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, d[3]-NMH. NMH and d[3]-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)
Creatinine:
The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)
Day(s) Performed
Monday, Wednesday, Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82542