N-Methylhistamine, 24 Hour Urine

Abbrev Code:NMH24   
Order Code:LAB8220Order Name:N-Methylhistamine, 24 hour Urine
Methodology:Liquid chromatography/Tandem mass spectrometry (LC-MS/MS); Enzymatic colorimetric assay.
CPT Codes: 82542 x1
Turnaround Time:Specimens are sent to reference laboratory Mon-Fri; results are reported within 3-7 days.
Special Instructions:Please indicate volume and duration of collection on collection and aliquot container.

This test is for timed urine collection only.  Random urine collections are preferred for patients with episodic symptoms, for example in the context of allergic reactions, brought on by specific environmental factors. For random specimens see N-Methylhistamine, Random Urine.

This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared by the U.S. Food and Drug Administration.

Collection Instructions

Specimen:Urine timed
Optimal Volume:Submit entire collection; analysis requires 3 mL.
Minimum\Peds Volume:3 mL
Container:3 L plastic jug
Collection Instructions:Store specimen refrigerated during collection.  Do not use preservative.
Patient Preparation:Patient must not be taking monoamine oxidase inhibitors (MAQIs) or aminoguanidine as these medications increase N-Methylhistamine (NMH) levels.
Causes for Rejection:Preserved urine; random collection.

Processing and Shipping

Specimen Processing:Aliquot 5 mL, 3 mL minimum.  Store refrigerated.
Shipping Instructions:Ship refrigerated.
Stability:28 days room temperature, refrigerated (preferred) and frozen.
Test Performed at or Referral Lab Lab Sendouts  (Mayo Medical Laboratories)
Referral Lab number:NMH24


Reference Range:
0-5 y 120-510 mcg/g creatinine
6-16 y 70-330 mcg/g creatinine
Greater than 16 y 30-200 mcg/g creatinine
Use:Screening for 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.

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