Which sample is used for measuring hemoglobin concentration in a laboratory CBC?

Which sample is used for measuring hemoglobin concentration in a laboratory CBC?

• A. Serum
• B. Plasma
• C. Whole blood
• D. Blood smear

Answer: (C)

Hemoglobin concentration comes from the Hb contained inside red blood cells, so the sample must include the cellular component that carries Hb. Serum and plasma are the liquid portions of blood with cells removed, so they lack intact red blood cells and cannot directly reflect total Hb. A blood smear is used to assess cell appearance and morphology, not to quantify Hb. In a CBC, a whole blood sample is collected and then the analyzer MPH or lyses the cells to release Hb for measurement, which is why whole blood is the appropriate sample.

Hemoglobin concentration comes from the Hb contained inside red blood cells, so the sample must include the cellular component that carries Hb. Serum and plasma are the liquid portions of blood with cells removed, so they lack intact red blood cells and cannot directly reflect total Hb. A blood smear is used to assess cell appearance and morphology, not to quantify Hb. In a CBC, a whole blood sample is collected and then the analyzer MPH or lyses the cells to release Hb for measurement, which is why whole blood is the appropriate sample.