Overview: Absolute Lymphocyte Count Test
Introduction: The Absolute Lymphocyte Count Test measures lymphocytes, a type of white blood cell, to assess immune system function and diagnose conditions like infections, immune deficiencies, or leukemia, which can cause weakness or frequent infections. Aligned with 2023 hematology guidelines, it uses flow cytometry for accurate counting, aiding in identifying immune or malignant conditions. This test is essential for guiding immunosuppressive or anticancer therapies and improving outcomes in hematology.

Other Names: ALC Test, Lymphocyte Count Assay.

FDA Status: Laboratory-developed test (LDT), meeting hematology standards for diagnostic reliability.

Historical Milestone: Lymphocyte counting started in the early 20th century via microscopy. Flow cytometry in the 1980s improved accuracy, and by the 2000s, automated systems enhanced clinical utility for immune disorder diagnostics.

Purpose: Diagnoses immune disorders, infections, or blood cancers, guides therapy, and monitors disease in patients with symptoms like weakness or infections.

Test Parameters: 1. Absolute Lymphocyte Count

Pretest Condition: No fasting required. Collect whole blood at any time. Report symptoms like frequent infections, fatigue, or medications (e.g., chemotherapy) affecting lymphocytes.

Specimen: 2-5 mL whole blood (EDTA tube). Transport in a biohazard bag within 24 hours at room temperature to preserve cell viability.

Sample Stability at Room Temperature: 24 hours

Sample Stability at Refrigeration: 48 hours

Sample Stability at Frozen: Not frozen, as cells may lyse.

Medical History: Document infections, immune disorders, or family history of leukemia. Include current medications, especially immunosuppressants or chemotherapy.

Consent: Written consent required, detailing the test's purpose, diagnostic implications, and potential therapy needs.

Procedural Considerations: Employs flow cytometry to count lymphocytes. Results are available in 1-2 days, supporting timely diagnosis.

Factors Affecting Result Accuracy: Chemotherapy or steroids may reduce lymphocyte counts. Hemolysis or improper storage can degrade samples. Recent infections may elevate counts temporarily.

Clinical Significance: Low lymphocyte counts suggest immune deficiency or leukemia, prompting further testing. Elevated counts may indicate viral infections or chronic lymphocytic leukemia.

Specialist Consultation: Consult a hematologist or immunologist for result interpretation. Oncology referral is advised for suspected malignancies.

Additional Supporting Tests: Flow cytometry immunophenotyping, bone marrow biopsy, or viral serology to confirm underlying causes.

Test Limitations: Non-specific changes require clinical correlation. Transient lymphocytosis or lymphopenia may need repeat testing.

References: American Society of Hematology Guidelines, 2023; Swerdlow SH, Blood, 2022.