The most popular blood test for iron-deficiency anemia is the ferritin blood test. This test measures how much iron your body is storing at a given time in the liver, spleen, and bone marrow. This test is a good indicator of whether or not your body has enough iron for normal function.Also, the hemoglobin (Hgb) concentration and the mean corpuscular volume (MCV) of red blood cells are measured to detect iron deficiency, a lack of oxygen in the blood due to having fewer and smaller red blood cells in your system.