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Test 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, B

Specimen Type

Whole blood

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Refrigerated (preferred) 72 hours
  Ambient  48 hours

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

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

Day(s) Performed

Tuesday

Report Available

3 to 9 days

Performing 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