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Test Code CTXP Cerebrotendinous Xanthomatosis, Plasma


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 HSMP / Hepatosplenomegaly Panel, Plasma. If this test (CTXP) is ordered with either GPSYP / Glucopsychosine, Plasma or OXNP / Oxysterols, Plasma, the individual tests will be canceled and HSMP ordered.



Specimen Required


Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium heparin, lithium heparin), yellow top (ACD B)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.3 mL

Collection Instructions:

1. Centrifuge at 4° C if possible

2. Aliquot plasma into a plastic vial. Do not disturb or transfer the buffy coat layer.

3. Send frozen.

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.

Secondary ID

65631

Useful For

Evaluating patients with a clinical suspicion of cerebrotendinous xanthomatosis (CTX) using plasma specimens

 

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, P

Specimen Type

Plasma

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen 65 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

7-ALPHA-HYDROXY-4-CHOLESTEN-3-ONE (7a-C4)

Cutoff: ≤0.300 nmol/mL

 

7-ALPHA,12 ALPHA–DIHYDROXYCHOLEST-4-en-3-ONE (7a12aC4)

Cutoff: ≤0.100 nmol/mL

Day(s) Performed

Tuesday, Thursday

Report Available

3 to 7 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
CTXP Cerebrotendinous Xanthomatosis, P 92746-7

 

Result ID Test Result Name Result LOINC Value
BA4379 Interpretation (CTXP) 59462-2
BA4376 7a-hydroxy-4-cholesten-3-one 92761-6
BA4377 7a,12a-dihydroxycholest-4-en-3-one 92758-2
BA4378 Reviewed By 18771-6