340 Anatomy & Physiology Essentials Copyright Goodheart-Willcox Co., Inc. marrow. When bone marrow stem cells are damaged, they cannot produce a sufficient number of RBCs, WBCs, and platelets. The small number of blood cells that are manufactured in the bone marrow have difficulty developing into mature blood cells, resulting in aplastic anemia. Bone marrow stem cell damage may be caused by: • toxins (such as those found in pesticides) • radiation therapy or chemotherapy • infectious diseases (for example, hepatitis, Epstein-Barr virus, human immunodeficiency virus (HIV), and autoimmune disorders such as rheumatoid arthritis and lupus) • cancer in another part of the body that affects the bone marrow • idiopathic causes (unknown causes) Treatments for aplastic anemia are aimed at reducing the factors that are damaging bone marrow stem Acquired Anemias Many conditions and factors may cause an acquired anemia. Examples include a dietary deficiency, blood loss, hormones, exposure to parasitic worms, chronic diseases, pregnancy, or damage to a specific part of the body. Iron-Defi cient Anemia The most common type of anemia, iron-deficient anemia, accounts for nearly 50% of all anemias worldwide. Iron-deficient anemia typically results from an insufficient dietary intake of iron or loss of iron from intestinal bleeding. Parasitic worms that result in intestinal bleeding are the main cause of iron-deficient anemia world- wide. Parasitic worms are most commonly found in developing or low-income countries. Pregnant women may also suffer from iron- deficient anemia. This happens because their bodies must supply the fetus with hemoglobin, depleting the woman’s own iron levels. (Recall that the heme molecule in hemoglobin is composed of iron.) If iron-deficient anemia is caused by a poor diet, an iron supplement can be prescribed. Foods rich in iron, such as leafy, green vegetables, are also recommended (Figure 11.16). Aplastic Anemia A rare but serious condition known as aplastic anemia is caused by damage to the stem cells in the bone Goodheart-Willcox Publisher Figure 11.15 The results of a CBC can be used to determine the presence of a disease or disorder. The Low/High column shows counts lower (L) or higher (H) than normal. Complete Blood Count Example Test Results Test Results Low/High Units Normal Ranges CBC with Differential Red Blood Count 3.5 (L) × 10-6/μl 4.1–5.1 (F) / 4.70–6.10 (M) Hemoglobin 10.8 (L) g/dl 12.0–16.0 (F) / 14.0–18.0 (M) Hematocrit 31.1 (L) % 37.0–48.0 (F) / 42.0–52.0 (M) Platelets 302 × 10-3/μl 140–415 White Blood Count 7.2 × 10-3/μl 4.5–11 Lymphocytes 48 (H) % 17–44 Monocytes 7.0 % 3–10 Neutrophils 43 (L) % 45–76 Eosinophils 2.0 % 0–4 Basophils 0 % 0–2 M = Male F = Female Elevated white blood count may signal disease or infection. Low red blood count, hemoglobin, and hematocrit signal anemia. Robyn Mackenzie/Shutt erstock.com Figure 11.16 One way to help fight iron-deficient anemia is to adopt a diet rich in leafy green vegetables like those shown here.