N Methylhistamine, 24 Hour Urine (Sendout)

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General Information

Lab Name
N Methylhistamine, 24 Hour Urine (Sendout)
Lab Code
RUNMHT
Epic Ordering
N-Methylhistamine, 24 Hour Urine (Sendout)
External Test Id
NMH24
Description

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
  • Monitoring therapeutic progress in conditions that are associated with secondary, localized, low-grade persistent, mast-cell proliferation and activation such as interstitial cystitis

Patient Preparation:

  • Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine, as these medications increase N-methylhistamine (NMH) levels.
  • Patient should avoid consuming histamine-rich food 24 hours prior to/during collection (e.g., cheese, chicken, liver, eggplant, sauerkraut, sirloin steak, spinach, tomatoes, wine, or yogurt).

Ordering Requirements: Pre-approved for UW Medicine Allergy Clinics. Orders from other locations require Laboratory Medicine Resident (LMR) approval.

Ordering Note: This test is for timed urine collections only. For random urine collections, refer to N-Methyl Histamine (MIAA), Random Urine (Sendout) [OLTG #478].

Synonyms
1-Methylhistamine, MIAA-Urine, N-methylhistamine, N-Methylimidazoleacetic Acid-Urine, NMH24
Components

Interpretation

Method

N-Methylhistamine: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Creatinine: Enzymatic Colorimetric Assay

Reference Range
See individual components
Ref. Range Notes

Reference Ranges:

0-5 years: 120-510 mcg/g creatinine
6-16 years: 70-330 mcg/g creatinine
>16 years: 30-200 mcg/g creatinine

Ordering & Collection

Specimen Type
Urine
Collection

24 Hour Collection: Collect urine for 24 hours in a preservative-free amber polyethylene urine collection container. Refrigerate during collection (preferred). Record the collection interval.

  • The application of temperature controls (refrigeration) must occur within 4 hours of completion of the collection.
  • If the total volume provided is less than 300 mL, the order will be changed to the random urine test by Mayo Clinic.
Approval Required
Pre-approved for UW Medicine Allergy Clinics. Orders from other locations require Laboratory Medicine Resident (LMR) approval.
Handling Instructions

Outside Laboratories:

  • Mix urine well. Measure and record total volume. Document the total volume and collection interval on the DLMP requisition.
  • Aliquot 5 mL urine to a plastic screw-cap vial and refrigerate specimen.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 14 days.

Quantity
requested: 5 mL urine
minimum: 3 mL urine

Processing

Processing
  • The application of temperature controls (refrigeration) must occur within 4 hours of completion of the collection.
  • Mix specimen well. Measure and record total volume.
  • Document the collection interval and total volume on the requisition. Provide Sendouts with a copy.
  • Aliquot 5 mL urine to a plastic, screw-capped vial and refrigerate.

Result-at-entry:

  • RUMINT (Collection Interval): <Enter the collection interval in hr.>
  • RUMTV (Total Volume): <Enter the total volume in mL.>

Sendouts:

  • Order Mayo Test: NMH24.
  • Interfaced: Yes.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 14 days.

Performance

LIS Dept Code
Sendouts Mayo Lab (RF) (MARF)
Performing Location(s)
Sendout Mayo Clinic Laboratories
800-533-1710

200 First Street Southwest
Rochester, MN 55901
Sendout Mayo Clinic Laboratories (Superior Drive)
800-533-1710

3050 Superior Drive NW
Rochester, MN 55901
Frequency
Performed: Tuesday, Thursday. Report Available: 3-7 days from sample receipt.
Available STAT?
No

Billing & Coding

CPT codes
82542
LOINC
44340-8
Interfaced Order Code
UOW4981