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

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.

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.