Update Type: Test Code Change
Test Updated: 03/01/2023
Test Overview
Test Methodology

LTE4: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
AACT: Enzymatic Colorimetric Assay

Test Usage

Evaluating patients suspected of having systemic mastocytosis

Identification of aspirin sensitivity in patient respiratory diagnoses

Reference Range *

< or equal to 104 pg/mg creatinine

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

Patients taking 5-lipoxygenase inhibitor Zileuton/Zyflo may have decreased concentrations of leukotriene E4 (LTE4) if dosage has not been discontinued for 48 hours. If possible, discontinue for 48 hours before testing.

Test Details
Days Set Up
Tuesday, Friday
Analytic Time

3 - 9 days

Soft Order Code
MRLE4 (random) or MTLE4 (24 hour)
  • RLTE4
  • TLTE4
Reference Laboratory
Mayo RLTE4 or TLTE4
Special Testing
Specimen Requirements
Collection Instructions

Send urine in a plastic cup/container to Specimen Processing refrigerated with no preservative.

Alternate Specimen
Refrigeration is the preferred preservative. But acceptable others are: 50 % acetic acid, boric acid or sodium carbonate.
Normal Volume
4 mL
Minimum Volume
1 mL
Storage Temperature
Refrigerated preferred, frozen acceptable
Additional Information

Test sent to Mayo Clinic Laboratories.

CPT Code
Fee Code