Cerebrotendinous Xanthomatosis, Blood Spot

Casandra

Casandra Test Code MC88634Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID CTXBSCPT Code 82542

Cerebrotendinous Xanthomatosis, Blood Spot

Clinical Use

Use

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder of bile acid synthesis resulting from the deficiency of the mitochondrial enzyme, sterol 27-hydrolase. It leads to increased storage of cholestenol and ketosterol bile acid precursors in tissues and deficiency of chenodeoxycholic acid. This test is crucial for evaluating patients suspected of CTX, as it measures elevated levels of bile acid precursors such as 7-alpha-hydroxy-4-cholesten-3-one (7a-C4) and 7-alpha,12-alpha-dihydroxycholest-4-en-3-one (7a12aC4) in dried blood spot specimens. Diagnosis and early treatment with chenodeoxycholic acid can improve clinical outcomes.

Special Instructions

For accurate specimen collection, ensure the blood dries completely on filter paper in a horizontal position for at least 3 hours. Do not expose the specimen to heat or direct sunlight and keep it dry. This test can be part of the Hepatosplenomegaly Panel, Blood Spot if ordered with other specific tests, causing cancellations if ordered as individual tests.

Limitations

This test is not suitable for identifying carriers of CTX or evaluating bile acid malabsorption. Elevations in bile acid precursors might also occur in patients with bile acid malabsorption or ileal resection, potentially causing diagnostic confusion. Proper specimen handling is vital to avoid rejection issues like serum rings or insufficient specimen.

Test Details

New York Approved