Cerebrotendinous Xanthomatosis, Blood Spot
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
Not provided.
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.
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
7-alpha-hydroxy-4-cholesten-3-one
Analyte7-alpha,12-alpha-dihydroxycholest-4-en-3-one
Analyte
LOINC Codes
- 92739-2 - CTX Pnl DBS
- 59462-2 - Clinical biochemist review
- 92763-2 - 7a-OH-4-chol-3-one DBS-sCnc
- 92760-8 - 7a12aDiOHchol4en3one DBS-sCnc
Result Turnaround Time
3-7 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
2 Blood spots
Minimum Volume
1 Blood spot
Container
Blood Spot Collection Card (Filter Paper)
Collection Instructions
Let blood dry completely on filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.
Storage Instructions
Keep specimen dry.
Causes for Rejection
Blood spot showing serum rings, Insufficient specimen, Layering, Multiple applications
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 10 days |
| Refrigerated | 10 days |
| Frozen | 59 days |
