Blood work:
A complete guide for monitoring HIV

May 2007     View PDF     En español

Red Blood Cells: The Oxygen Carriers

Red Blood Cell (RBC) Count:
RBCs are produced in your bone marrow, and they carry oxygen and carbon dioxide through your body. The RBC count is the number of red blood cells found in a small amount of blood called a cubic milliliter, or mL. Normal levels for men range from 4.5–6.1 million/mL, and for women 4.0–5.3 million/mL. It’s not uncommon for people with HIV to have RBC values below normal.

Slightly lower values should not be cause for alarm. However, greatly lower numbers can be a sign of anemia. Symptoms include fatigue, shortness of breath, pale skin color and menstrual problems. Anemia can be caused by some medicines and/or illness. Low RBC counts occur with lower hemoglobin and hematocrit levels. Anemia may be treated with iron supplements, erythropoietin (Epogen) or in severe instances, a blood transfusion.

Hemoglobin:
Hemoglobin is a RBC protein that carries oxygen through the body. Normal levels in women are 12–16 grams per deciliter (g/dl) and in men 14–18g/dl. It’s not uncommon for people with HIV to have lower than normal hemoglobin levels. This is usually due to fewer RBCs produced by the bone marrow because of HIV or some anti-HIV drugs that suppress the marrow.

Drugs that cause bone marrow suppression will also lower hemoglobin counts. People with HIV who have mild anemia sometimes take iron supplements or erythropoietin (Epogen), a hormone that stimulates the production of RBCs to increase hemoglobin counts. If anemia is severe, however, erythropoietin therapy should not replace a blood transfusion.

Hematocrit:
The hematocrit is another way to measure RBCs. It is the percentage of blood cells in your body that are red blood cells. Normal values range in men from 40–54% and in women 37–47%. Hematocrit values indicate the thickness of the blood as well as its ability to carry oxygen. A low hematocrit also indicates anemia.

Mean Corpuscular Volume (MCV):
The MCV measures the average size of red blood cells. The average MCV ranges from 80–100 femtoliters (fL). A low MCV shows that cells are smaller than normal. This may be due to an iron deficiency or chronic disease. MCV is generally higher than normal in people taking Retrovir (zidovudine, AZT) or in people with vitamin B12 and folic acid deficiencies.

Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC):
These measure the amount and volume of hemoglobin in an average cell. These are less important but help to detect various anemias and leukemias.