Which laboratory test measures blood levels of antibodies to particular antigens?

• A. Complete blood count (CBC)
• B. Antibody titer (serologic titer)
• C. Erythrocyte sedimentation rate (ESR)
• D. Hematocrit (Hct)

Answer: (B)

Verified step by step guidance

1. Understand the purpose of each laboratory test listed: Complete Blood Count (CBC) measures the overall number and types of blood cells; Erythrocyte Sedimentation Rate (ESR) measures inflammation by how quickly red blood cells settle; Hematocrit (Hct) measures the proportion of red blood cells in blood.
2. Recognize that measuring blood levels of antibodies to specific antigens involves detecting the immune response, which is not the function of CBC, ESR, or Hct.
3. Identify that an Antibody titer (serologic titer) is a laboratory test designed specifically to measure the concentration of antibodies in the blood against particular antigens.
4. Recall that antibody titers are used to assess immunity, diagnose infections, or monitor immune status by quantifying antibody levels through serial dilution and detection methods.
5. Conclude that the correct test for measuring blood levels of antibodies to particular antigens is the Antibody titer (serologic titer).