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HelpOrder Code 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, USpecimen Type
UrineSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Frozen (preferred) | 28 days |
| Refrigerated | 7 days | |
| Ambient | 24 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
LEUKOTRIENE E4
≤104 pg/mg creatinine
CREATININE
≥18 years old: 16-326 mg/dL
Reference values have not been established for patients who are younger than 18 years of age.
Method Description
Leukotriene E4:
The specimen and an internal standard are assayed by liquid chromatography tandem mass spectrometry(LC-MS/MS). The analyte is detected by multiple-reaction monitoring.(Lueke AJ, Meeusen JW, Donato LJ, Gray AV, Butterfield JH, Saenger AK: Analytical and clinical validation of an LC-MS/MS method for urine leukotriene E4: A marker of systemic mastocytosis. Clin Biochem. 2016;49[13-14]:979-982)
Creatinine:
This enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)
Day(s) Performed
Monday, Tuesday, Thursday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82542
82570