Leukotriene E4 (LTE4), Random Urine (Sendout)

General Information

Lab Name

Lab Code

1070

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], urinary 2,3-dinor 11 beta-prostaglandin F2 alpha (OLTG #692) and urinary N-methylhistamine (OLTG #478).

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.

Ordering Requirements: Pre-approved for UW Medicine Allergy Clinics. 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 separate test Leukotriene E4, 24 Hour Urine (Sendout) [RULTE4].

Synonyms

Cysteinyl Leukotriene, LTE4, Mast Cell Activation Syndrome, Mastocytosis, RLTE4, Systemic Mast Cell Activation

Interpretation

Method

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

Creatinine: Enzymatic Colorimetric Assay

Ref. Range Notes

Reference Range:

Leukotriene E4:

< or =104 pg/mg creatinine

Interpretation: Elevated urinary leukotriene E4 (LTE4) 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: Patients taking 5-lipoxygenase inhibitor zileuton/Zyflo may have decreased concentrations of leukotriene E4 (LTE4) if dosage has not been discontinued for 48 hours. 11-trans-LTE4 interferes with the LTE4 analysis.

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

Pre-approved for UW Medicine Allergy Clinics. Orders from all other locations require Laboratory Medicine Resident (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: 28 days; Refrigerated: 7 days; Ambient: 24 hours.

Quantity

requested: 5 mL urine
minimum: 2 mL urine

Processing

Processing

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

Login: SEND1-;FREEZE

RSNDT1: MAYO
RSTYP1: URN-RAND
RTSRQ1: ;Leukotriene E4, Random Urine (Mayo Test RLTE4)

Sendouts:

Order Mayo Test: RLTE4.

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

Performance

LIS Dept Code

Performing Location(s)