Alpha-L-Iduronidase, Leukocytes

Casandra

Casandra Test Code MC62537Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID IDUAWCPT Code 82657

Alpha-L-Iduronidase, Leukocytes

Clinical Use

Use

This test is useful for diagnosing mucopolysaccharidosis I, including Hurler, Scheie, and Hurler-Scheie syndromes in leukocytes. It provides diagnostic testing for patients with clinical signs and symptoms suspicious for mucopolysaccharidosis type I (MPS I). Enzyme testing is included in the diagnostic workup for infants following a positive newborn screen result for MPS I. The test measures the activity of alpha-L-iduronidase enzyme to confirm a diagnosis of MPS I, as deficiency can lead to a wide range of symptoms due to glycosaminoglycan accumulation.

Special Instructions

This test is preferred for diagnostic testing rather than for determining carrier status. For carrier detection, order IDUA / Mucopolysaccharidosis Type I, IDUA Gene Sequencing with Deletion/Duplication, Varies. Collect and send whole blood specimen in original tube without aliquoting. Specimens should be collected Monday through Thursday only, and not the day before a holiday. The specimen is optimal when shipped refrigerated and arrives within 6 days of collection.

Limitations

The presence of a pseudodeficiency allele may cause reduced activity of alpha-L-iduronidase in the artificial substrate, resulting in values below the normal reference range but higher than typical for MPS I patients. This test does not differentiate between Hurler and Scheie syndromes. Enzyme levels may appear normal in individuals receiving enzyme replacement therapy or who have undergone hematopoietic stem cell transplant. Enzymatic testing is not reliable for carrier detection.

Test Details

New York Approved