Leukotriene E4 (LTE4), Random Urine (Sendout)

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General Information

Lab Name
Leukotriene E4 (LTE4), Random Urine (Sendout)
Lab Code
RURLT4
Epic Name
Leukotriene E4 (LTE4), Random Urine (Sendout)
External Test Id
RLTE4
Description

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).
  • Increased excretion of LTE4 is nonspecific and should not be used alone to make a clinical diagnosis of a MC activation disease.

Test Highlights: Quantitation of urinary metabolites of histamine, prostaglandin D2, and leukotriene E4 may provide significant clues for the diagnosis and management of symptomatic patients with both clonal and nonclonal mast cell activation syndromes. The presence of 1 or more elevated levels of these biomarkers in urine greatly narrows diagnostic possibilities for causes of symptoms, informs the practitioner what specific metabolic pathways are involved, and targets the treatment in a specific, personalized fashion.

    For an optimal evaluation, testing for urinary leukotriene E4 should be accompanied with laboratory investigations for the presence of serum Tryptase [TRYPT], 2,3-Dinor 11 Beta-Prostaglandin F2 Alpha, Random Urine (Sendout) [RUR23B] and N Methylhistamine, Random Urine (Sendout) [RURNMH].

      Systemic mastocytosis is a heterogenous disease and lack of elevated LTE4 does not exclude the diagnosis of mast cell disease.

        Increased excretion of LTE4 has also been reported in the following conditions: asthma, eosinophilic pneumonia, respiratory syncytial virus infection, atopic dermatitis, Crohn disease, and rheumatoid arthritis.

          Patient Preparation: Patients taking 5-lipoxygenase inhibitor zileuton (Zyflo) may have decreased concentrations of leukotriene E4 (LTE4). If medically feasible, the patient should not take zileuton for 48 hours before specimen collection.

            Ordering Requirements: Test pre-approved for orders originating from Fred Hutch, UW Medicine, or The Vancouver Clinic Allergy Clinics (MSALL, UESALL, VANTVC). Orders from other locations require Laboratory Medicine Resident (LMR) approval.

              Ordering Note: This test is for random urine collections only. For timed collections, refer to Leukotriene E4, 24 Hour Urine (Sendout) [RULTE4].

              Synonyms
              Cysteinyl Leukotriene, LTE4, Mast Cell Activation Syndrome, Mastocytosis, RLTE4, Systemic Mast Cell Activation
              Components
              Code Name
              RURLTR Leukotriene E4 (LTE4), Random Urine
              RURCRE Creatinine, Random Urine

              Interpretation

              Method

              Leukotriene E4: Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

              Creatinine: Enzymatic Colorimetric Assay

              Reference Range
              See individual components
              Ref. Range Notes

              Reference Values:

              Leukotriene E4, Random Urine: < or =104 pg/mg creatinine
              Creatinine, Random Urine (> or =18 years): 16-326 mg/dL

              Interpretation: Elevated urinary leukotriene E4 concentrations above 104 pg/mg creatinine may be suggestive of mast cell activation syndrome if compatible features of disease are present.

              Interferences and Limitations

              Cautions:

              Mast cell (MC) activation disorder is a heterogenous disease, and the absence of elevated LTE4 does not exclude the diagnosis of MC disease.

              Increased excretion of LTE4 is nonspecific and should not be used alone to make a clinical diagnosis of a MC activation disease.

              This assay measures both LTE4 and the 11-trans-LTE4 as markers of MC release.

              Ordering & Collection

              Specimen Type
              Urine
              Collection

              Within a few hours of symptom onset, collect a random urine specimen in a preservative-free collection container.

              Approval Required
              Test pre-approved for orders originating from Fred Hutch, UW Medicine, or The Vancouver Clinic Allergy Clinics (MSALL, UESALL, VANTVC). Orders from other locations require LMR approval.
              Handling Instructions

              Outside Laboratories:

              • Aliquot 5 mL urine to a plastic screw-cap vial, leaving room for expansion. Freeze urine at -20°C while awaiting shipment. Transport samples on dry ice.
              • Indicate "random collection" on the DLMP requisition.

              Stability: Frozen (preferred): 28 days; Refrigerated: 7 days; Ambient: 24 hours.

              Quantity
              Requested: 5 mL urine
              Minimum: 2 mL urine

              Processing

              Receiving Instructions

              Transfer 5 mL urine to a plastic, screw-capped vial, leaving room for expansion. Freeze specimen at -20°C.

              Sendouts:

              • Order Mayo Test: RLTE4
              • Interfaced: Yes [Interface: 601; Worksheet: MAFZ]

              Stability: Frozen (preferred): 28 days; Refrigerated: 7 days; Ambient: 24 hours.

              Misc Sendout

              Performance

              Lab Department
              Sendouts Mayo Lab (RF)(MARF)
              Frequency
              Performed: Monday, Tuesday, Thursday. Reported: 2-9 days from sample receipt at Mayo Clinic Lab.
              Available STAT?
              No
              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

              Billing & Coding

              CPT Codes
              82542, 82570
              LOINC
              33343-5
              Interfaced Order Code
              UOW6217