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Test Code NMHIN N-Methylhistamine, 24 Hour, Urine

Reporting Name

N-Methylhistamine, U

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

Profile Information

Test ID Reporting Name Available Separately Always Performed
NMH N-Methylhistamine, U No Yes
NCTU Creatinine Concentration No Yes

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Urine


Specimen Required


Container/Tube: Plastic, 5-mL tube (T465)

Specimen Volume: 5 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. No preservative.

Additional Information:

1. 24-Hour volume is required.

2. 24-Hour collection is preferred, but random specimen is also acceptable.

3. See Urine Preservatives in Special Instructions for multiple collections.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 8 days
  Frozen  14 days
  Ambient  24 hours

Reference Values

0-5 years: 120-510 mcg/g creatinine

6-16 years: 70-330 mcg/g creatinine

>16 years: 30-200 mcg/g creatinine

Day(s) and Time(s) Performed

Tuesday, Thursday; 10 a.m.

Test Classification

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

CPT Code Information

82542

LOINC Code Information

Test ID Test Order Name Order LOINC Value
NMHIN N-Methylhistamine, U In Process

 

Result ID Test Result Name Result LOINC Value
NCTU_ Creatinine Conc 2161-8
21589 N-Methylhistamine, U 44340-8
TM73 Collection Duration 13362-9
VL63 Urine Volume 3167-4

Clinical Information

N-methylhistamine (NMH) is the major metabolite of histamine, which is produced by mast cells. Increased histamine production is seen in conditions associated with increased mast-cell activity, such as allergic reactions, but also in mast-cell proliferation disorders, in particular mastocytosis.

 

Mastocytosis is a rare disease. Its most common form, urticaria pigmentosa (UP), affects the skin and is characterized by multiple persistent small reddish-brown lesions that result from infiltration of the skin by mast cells. Systemic mastocytosis is caused by the accumulation of mast cells in other tissues and can affect organs such as the liver, spleen, bone marrow, and small intestine. The mast-cell proliferation in systemic mastocytosis can be either benign or malignant. In children, benign systemic mastocytosis tends to resolve over time, while in most, but not all adults, the disease is progressive. Systemic mastocytosis may or may not be accompanied by UP.(1,3) Patients with UP or systemic mastocytosis can have symptoms ranging from itching, gastrointestinal distress, bone pain, and headaches; to flushing and anaphylactic shock.

 

Diagnosis of mastocytosis is made by bone marrow biopsy; however, patients with systemic mastocytosis usually exhibit elevated levels of NMH.(1-5) Other biochemical markers include 11-beta prostaglandin F(2) alpha, a metabolite of prostaglandin D2 (23BPG / 2,3 Dinor-11Beta-Prostaglandin F2 Alpha, Urine), and tryptase, alpha or beta (TRYPT / Tryptase, Serum).

Interpretation

Increased concentrations of urinary N-methylhistamine (NMH) are consistent with urticaria pigmentosa (UP), systemic mastocytosis, or mast-cell activation. Because of its longer half-life, urinary NMH measurements have superior sensitivity and specificity than histamine, the parent compound. However, not all patients with systemic mastocytosis or anaphylaxis will exhibit concentrations outside the reference range and healthy individuals may occasionally exhibit values just above the upper limit of normal.

 

The extent of the observed increase in urinary NMH excretion is correlated with the magnitude of mast-cell proliferation and activation, UP patients, or patients with other localized mast-cell proliferation and activation, show usually only mild elevations, while systemic mastocytosis and anaphylaxis tend to be associated with more significant rises in NMH excretion (2-fold or more). There is, however, significant overlap in values between UP and systemic mastocytosis, and urinary NMH measurements should not be relied upon alone in distinguishing localized from systemic disease.

 

Up to 25% variability in spot-urine excreted levels may be observed, making 24-hour urine collections preferable for cases with borderline results.

 

Children have higher NMH levels than adults. By the age of 16, adult levels have been reached.

Clinical Reference

1. Roberts LJ II, Oates JA: Disorders of vasodilator hormones: the carcinoid syndrome and mastocytosis. In Williams Textbook of Endocrinology. Eighth edition. Edited by JD Wilson, DW Foster. Philadelphia, WB Saunders Company, 1992, pp 1625-1634

2. Akin C, Metcalfe DD: Mastocytosis. In Allergic Skin Disease: A Multidisciplinary Approach. Edited by DYM Leung, MW Greaves. New York. Marcel Dekker, Inc., 2000, pp 337-352

3. Keyzer JJ, de Monchy JG, van Doormaal JJ, van Voorst Vader PC: Improved diagnosis of mastocytosis by measurement of urinary histamine metabolites. N Engl J Med 1983;309(26):1603-1605

4. Heide R, Riezebos P, van Toorenbergen AW, et al: Predictive value of urinary N-methylhistamine for bone marrow involvement in mastocytosis. J Invest Dermatol 2000;115(3):587

5. Van Gysel D, Oranje AP, Vermeiden I, et al: Value of urinary N-methylhistamine measurements in childhood mastocytosis. J Am Acad Derm 1996;35(4):556-558

Analytic Time

3 days

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

Method Name

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

NCTU: Enzymatic Colorimetric Assay

Urine Preservative Collection Options

Ambient

Yes

Refrigerated

Preferred

Frozen

Yes

6N HCl

Yes

50% Acetic Acid

Yes

Na2CO3

Yes

Toluene

Yes

6N HNO3

Yes

Boric Acid

Yes

Thymol

Yes