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HelpTest ID 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
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
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
65631Useful 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.
Specimen Type
PlasmaSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| 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 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82542