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HelpTest Code CTXWB Cerebrotendinous Xanthomatosis, Blood
Ordering Guidance
For assessment of bile acid malabsorption in patients with irritable bowel syndrome-diarrhea, order 7AC4 / 7AC4, Bile Acid Synthesis, Serum.
This test is also available as a part of a panel; see HSMWB / Hepatosplenomegaly Panel, Blood. If this test (CTXWB) is ordered with either GPSYW / Glucopsychosine, Blood or OXYWB / Oxysterols, Blood, the individual tests will be canceled and HSMWB ordered.
Specimen Required
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Green top (sodium heparin, lithium heparin), yellow top (ACD B)
Specimen Volume: 1 mL
Collection Instructions: Send whole blood in original vial. Do not aliquot.
Forms
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Useful For
Evaluating patients with a clinical suspicion of cerebrotendinous xanthomatosis (CTX)
Monitoring of individuals with CTX on chenodeoxycholic acid (CDCA) therapy
This test is not useful for the identification of carriers
This test is not useful for the evaluation of bile acid malabsorption
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
Cerebrotendinous Xanthomatosis, BSpecimen Type
Whole bloodSpecimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated (preferred) | 72 hours | |
| Ambient | 48 hours |
Reference Values
7-ALPHA-HYDROXY-4-CHOLESTEN-3-ONE (7a-C4)
Cutoff: ≤0.750 nmol/mL
7-ALPHA,12-ALPHA-DIHYDROXYCHOLEST-4-en-3-ONE (7a12aC4)
Cutoff: ≤0.250 nmol/mL
Interpretation
An elevation of 7-alpha-hydroxy-4-cholesten-3-one (7a-C4) and 7-alpha,12-alpha-dihydroxycholest-4-en-3-one (7a12aC4) is strongly suggestive of cerebrotendinous xanthomatosis.
Clinical Reference
1. Mignarri A, Magni A, Del Puppo M, et al: Evaluation of cholesterol metabolism in cerebrotendinous xanthomatosis. J Inherit Metab Dis. 2016 Jan;39(1):75-83
2. Nie S, Chen G, Cao X, Zhang Y: Cerebrotendinous xanthomatosis: a comprehensive review of pathogenesis, clinical manifestations, diagnosis, and management. Orphanet J Rare Dis. 2014 Nov 26;9:179
3. DeBarber AE, Luo J, Star-Weinstock M, et al: A blood test for cerebrotendinous xanthomatosis with potential for disease detection in newborns. J Lipid Res. 2014 Jan;55(1):146-154
4. Federico A, Gallus GN: Cerebrotendinous xanthomatosis. In: Adam MP, Everman DB, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2003. Updated March 17, 2022. Accessed December 28, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1409/
5. Lutjohann D, Stellaard F, Bjorkhem I: Levels of 7alpha-hydroxycholesterol and/or 7alpha-hydroxy-4-cholest-3-one are the optimal biochemical markers for the evaluation of treatment of cerebrotendinous xanthomatosis. J Neurol. 2020 Feb;267(2):572-573. doi: 10.1007/s00415-019-09650-0
6. Mandia D, Chaussenot A, Besson G, et al: Cholic acid as a treatment for cerebrotendinous xanthomatosis in adults. J Neurol. 2019 Aug;266(8):2043-2050. doi: 10.1007/s00415-019-09377-y
Day(s) Performed
Tuesday
Report Available
3 to 9 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CTXWB | Cerebrotendinous Xanthomatosis, B | 92737-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| BA4365 | Interpretation (CTXWB) | 59462-2 |
| BA4363 | 7a-hydroxy-4-cholesten-3-one | 92762-4 |
| BA4364 | 7a,12a-dihydroxycholest-4-en-3-one | 92759-0 |
| BA4366 | Reviewed By | 18771-6 |