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Order 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)


Useful For

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

 

Monitoring 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, 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

Method Description

A 3-mm dried blood spot is extracted with internal standard. The extract is subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. The MS/MS is operated in the multiple reaction monitoring positive mode to follow the precursor to product species transitions for each analyte and internal standard. The ratio of the extracted peak areas to internal standard determined by the LC-MS/MS is used to calculate the concentration of in the sample.(Unpublished Mayo method)

Day(s) Performed

Tuesday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82542