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CD4 Subset Assay (LAB000658)
Test Mnemonic:

 CD4

Specimen Requirements:
Collection:

Collect blood aseptically by venipuncture into a sterile EDTA (Lavender-top tube) blood collection tube;a pediatric EDTA microtainer tube is also acceptable.

NOTE: Specimens collected on Friday must reach Galveston Lab by noon.  Use Streck Cyto-Chex BCT collection tubes (Streck Cat # 213361) to avoid test cancellations.  Time-sensitive specimens should not be collected late Friday or the eve of a holiday.
Container:

EDTA (Lavender-top tube).  Fill tube within +/- 10% from the fill line.

A pediatric EDTA microtainer tube is acceptable.
Minimum Volume:

1 ml
Storage/Transport:

Specimen must be stored at room temperature (18-25°C). DO NOT REFRIGERATE.
Specimen Preparation:

Specimen must be stained within 48 hours of draw and analyzed within 24 hours of staining.
Stability:

Specimen collected in standard EDTA tube is stable for 48 hours from the time of collection and stored at Room Temperature.

Specimen collected in Cyto-Chex BCT tube is stable for 5 days from the time of collection and stored at Room Temperature.
Causes for Rejection:
  • Clotted, hemolyzed, and quantity not sufficient.
  • Expired specimen.
  • Refrigerated specimen.
  • Specimen collected in an anticoagulant other than EDTA and Cyto-Chex BCT tube.
  • Over/under filled specimen tube.
  • Improperly labeled specimen.
  • Questionable specimen quality.
Reference Range:

By report (reports may vary based on instrumentation, patient age, and sex)
Turnaround Time:

 48 Hours from the time of receiving in the lab.

Note: Testing is performed Monday- Friday (8 am-5 pm).  Friday's cut-off is noon.
Methodology:

This assay is designed to enumerate percentage, and absolute cell counts of lymphocyte subsets in whole blood samples.  Whole blood is added with fluorochrome-labeled antibodies that bind specifically to cell surface antigens on lymphocytes.  After incubation, lysing, and fixation, percent and absolute lymphocytes counts are enumerated utilizing an internal quantitation standard, and are run on a Flow Cytometer instrument.
Performed:

University of Texas Medical Branch-Galveston 
Lab:

Hematopathology Division; Flow Cytometry Section; CSW 7.412
Synonyms:

CD4, Helper T-cell, CD4 positive T lymphocyte, T4
Clinical Indication:

CD4 subset assay is clinically indicated for assessing immune function, particularly in individuals with HIV infection, to monitor disease progression, treatment response, and the need for opportunistic infection prophylaxis.
CPT 4 Code:

  86361 
Note:

 
When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
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