1. What is CD4 Count?

The CD4 count is a test that measures the number of CD4 cells (T-helper cells) in a blood sample. These white blood cells play a crucial role in the immune system and are the primary target of HIV.

2. How Does the Calculator Work?

The calculator uses the CD4 count equation:

Where:

• \( ALC \) — Absolute lymphocyte count (cells/μL)
• \( CD4\% \) — Percentage of lymphocytes that are CD4+ cells

Explanation: The equation calculates the absolute CD4 count by multiplying the total lymphocyte count by the percentage of CD4+ cells.

3. Importance of CD4 Count

Details: CD4 count is essential for monitoring immune function in HIV patients, determining when to start antiretroviral therapy, and assessing risk for opportunistic infections.

4. Using the Calculator

Tips: Enter ALC (from CBC) in cells/μL and CD4 percentage (from flow cytometry). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal CD4 count?
A: Normal range is typically 500-1500 cells/μL. Below 200 indicates severe immune suppression.

Q2: How often should CD4 counts be monitored?
A: For HIV patients, typically every 3-6 months depending on treatment status and viral load.

Q3: What factors can affect CD4 count?
A: Time of day, recent infections, vaccinations, stress, and certain medications can cause temporary fluctuations.

Q4: Is this calculation as accurate as direct measurement?
A: While useful for estimation, direct measurement via flow cytometry is more accurate for clinical decision-making.

Q5: Can CD4 percentage be used alone?
A: Yes, CD4% (normal 30-60%) can be used when ALC is normal, but absolute count is generally preferred.