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Test Code CTXBS Cerebrotendinous Xanthomatosis, Blood Spot


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 HSMBS / Hepatosplenomegaly Panel, Blood Spot. If this test (CTXBS) is ordered with either GPSY / Glucopsychosine, Blood Spot or OXYBS / Oxysterols, Blood Spot, the individual tests will be canceled and HSMBS ordered.



Specimen Required


Supplies:

-Card-Blood Spot Collection (Filter Paper) (T493)

-Card-Postmortem Screening (Filter Paper) (T525)

Container/Tube:

Preferred: Blood Spot Collection Card (Filter Paper)

Acceptable: Whatman Protein Saver 903 filter paper, PerkinElmer 226 filter paper, Munktell filter paper, Postmortem Screening Card or collected with EDTA, sodium heparin, lithium heparin, or ACD B-containing devices

Specimen Volume: 2 Blood spots

Collection Instructions:

1. Let blood dry completely on filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

2. At least 1 spot should be complete (ie, unpunched).

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry.

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)


Secondary ID

65630

Useful For

Evaluating patients with a clinical suspicion of cerebrotendinous xanthomatosis (CTX) using dried blood spot specimens

 

Monitoring individuals with CTX on chenodeoxycholic acid 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, BS

Specimen Type

Whole blood

Specimen Minimum Volume

1 Blood spot

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Refrigerated (preferred) 10 days FILTER PAPER
  Frozen  59 days FILTER PAPER
  Ambient  10 days FILTER PAPER

Reject Due To

Blood spot showing serum rings Insufficient specimen Layering Multiple applications Reject

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
CTXBS Cerebrotendinous Xanthomatosis, BS 92739-2

 

Result ID Test Result Name Result LOINC Value
BA4361 Interpretation (CTXBS) 59462-2
BA4359 7a-hydroxy-4-cholesten-3-one 92763-2
BA4360 7a,12a-dihydroxycholest-4-en-3-one 92760-8
BA4362 Reviewed By 18771-6