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Test ID RLTE4 Leukotriene E4, Random, Urine

Ordering Guidance

Patients with mast cell activation syndrome may have chronically elevated leukotriene E4 (LTE4), however, in certain situations LTE4 can exhibit intermittent elevations. In these cases, a 24-hour urine collection is preferred. For 24-hour urine collection, order TLTE4 / Leukotriene E4, 24 Hour, Urine.

Additional Testing Requirements

For an optimal evaluation, testing for urinary leukotriene E4 should be accompanied with laboratory investigations for the presence of serum tryptase (TRYPT / Tryptase, Serum), urinary 2,3-dinor 11 beta-prostaglandin F2 alpha (23BPR / 2,3-Dinor 11 Beta-Prostaglandin F2 Alpha, Random, Urine) and urinary N-methylhistamine (NMHR / N-Methylhistamine, Random, Urine).

Specimen Required

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube: Plastic vial

Specimen Volume: 5 mL

Collection Instructions:

1. Within a few hours of symptom onset, collect a random urine specimen.

2. No preservative

3. Aliquot urine into a plastic vial and send frozen.

Useful For

Aiding in the evaluation of patients at-risk for mast cell activation syndrome (eg, systemic mastocytosis, IgE-mediated allergies, or aspirin-exacerbated respiratory disease) using random urine collections

Profile Information

Test ID Reporting Name Available Separately Always Performed
LTE4R Leukotriene E4, Random, U No Yes
CRTFR Creatinine, Random, U No Yes

Method Name

LTE4R: Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

CRTFR: Enzymatic Colorimetric Assay

Reporting Name

Leukotriene E4, Random, U

Specimen Type


Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen (preferred) 28 days
  Refrigerated  7 days
  Ambient  24 hours

Reference Values


≤104 pg/mg creatinine



≥18 years old: 16-326 mg/dL

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

Day(s) Performed

Monday, Thursday

Report Available

2 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information



LOINC Code Information

Test ID Test Order Name Order LOINC Value
RLTE4 Leukotriene E4, Random, U 33343-5


Result ID Test Result Name Result LOINC Value
603457 Leukotriene E4, Random, U 33343-5
CRTFR Creatinine, Random, U 2161-8