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N-Methylhistamine, 24 Hour, Urine

Important Note

Collect one plain Brown Jug when 2,3 Dinor 11 Beta-Prostaglandin F2 Alpha, N-Methylhistamine and Histamine are all ordered. One collection in a Plain Brown Jug is acceptable for all three tests.

Additional Codes


Advisory Information

Random urine collections are preferred for patients with episodic symptoms, for example in the context of allergic reactions, brought on by specific environmental factors. See NMHR / N-Methylhistamine, Random, Urine.

Specimen Required

Patient Preparation: Patient must not be taking monoamine oxidase inhibitors (MAOIs) or aminoguanidine as these medications increase N-methylhistamine (NMH) levels.

Supplies: Aliquot Tube, 5 mL (T465)

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 in Special Instructions for multiple collections.

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

Specimen Type


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

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



Males: 930-2955 mg/24 hours

Females: 603-1783 mg/24 hours


Reference values have not been established for patients who are less than 18 years of age.


For SI unit Reference Values, see

Day(s) and Time(s) Performed

Tuesday, Thursday; 10 a.m.

Analytic Time

3 days

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
NMH24 N-Methylhistamine, 24 Hr, U 44340-8


Result ID Test Result Name Result LOINC Value
CR_A Creatinine, 24 HR, U 2162-6
605159 N-Methylhistamine, 24 Hr 44340-8
TM10 Collection Duration 13362-9
VL8 Urine Volume 3167-4