Lymphocyte count (manual differential blood count)

What Is a Lymphocyte Count?

A lymphocyte count is a blood test that identifies the number of lymphocytes (a specific type of white blood cell) in your blood sample. These cells are crucial for immune function, helping your body fight infections and respond to illnesses. The test may be used to assess immune health, diagnose conditions like infections, or monitor treatments for diseases such as cancer or autoimmune disorders. Manual differential counts are often performed by trained medical professionals to provide detailed cell counts, including subtypes of lymphocytes.

Why Might You Need This Test?

Your doctor may order a lymphocyte count if you have symptoms like frequent infections, fatigue, or unexplained weight loss. It can also be used to monitor conditions such as leukemia, lymphoma, HIV, or other immune-related diseases. Sometimes, it’s part of a routine check-up or to evaluate how your body is responding to treatment.

How Is the Test Performed?

This test involves drawing blood from a vein in your arm. The blood sample is then examined under a microscope by a trained technician or pathologist to count the lymphocytes and sometimes their subtypes. Manual differential counts provide more detailed results compared to automated tests, which may not distinguish between different lymphocyte types.

What Do the Results Mean?

Results can vary depending on your health and medical history. A low lymphocyte count may suggest immune suppression, infections, or certain cancers. A high count could indicate an overactive immune response, chronic infections, or other conditions. Your doctor will interpret the results in the context of your overall health and symptoms.