N-Methylhistamine, 24-Hour Urine
Also known as: NMETHYL U
Use
The N-Methylhistamine, 24-Hour Urine test aids in the evaluation of patients with allergic signs and symptoms, such as anaphylaxis. It may assist in diagnosing and monitoring mast cell activation disorders or in evaluating histamine production over a longer time frame. It is particularly beneficial for conditions where histamine metabolism and its byproducts are of clinical interest, such as in mast cell disorders.
Special Instructions
A 24-hour urine collection of 300 mL or greater is required. If submitting a random urine or 24-hour collection with a total volume of less than 300 mL, consider the N-Methylhistamine, Random Urine test instead. Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine as these medications increase N-methylhistamine levels. Collection duration and urine volume must be provided for testing.
Limitations
The test is not performed at ARUP Laboratories; separate specimens must be submitted when multiple tests are ordered. The method is highly specific, but any interfering factors should be considered in the context of the clinical scenario. Ambient stability is 2 weeks; refrigerated and frozen stability is 28 days. Incorrect collection or storage could affect analytic outcomes.
New York Approved
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 44340-8
Result Turnaround Time
6-12 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
5 mL
Minimum Volume
3 mL
Container
ARUP standard transport tubes
Collection Instructions
From a well-mixed 24-hour collection transfer 5 mL urine to ARUP standard transport tubes.
Patient Preparation
Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine.
Storage Instructions
Refrigerated is preferred but room temperature or frozen is also acceptable.
Causes for Rejection
Collection duration and urine volume missing; volume less than 300 mL.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 weeks |
| Refrigerated | 28 days |
| Frozen | 28 days |