Blood Cell Counts, Types, and Hematologic Disorders: Key Concepts for Medical Students

Normal RBC count in a typical healthy person per cubic millimeter of blood.

4.5-6 million RBCs/mm³

Normal WBC count in a typical healthy person per cubic millimeter of blood.

5,000-10,000 WBCs/mm³

Normal platelet count in a typical healthy person per cubic millimeter of blood.

150,000-400,000 platelets/mm³

Approximate normal hemoglobin concentration in females.

14 g/dL

Approximate normal hemoglobin concentration in males.

15 g/dL

Site where RBCs and platelets are produced.

Red bone marrow

Blood cells produced in red bone marrow and lymphoid tissue that function as part of the immune system.

White blood cells

WBCs that defend the body against bacteria by phagocytosis.

Neutrophils

WBCs that increase enormously during acute infections as bone marrow releases its reserves.

Neutrophils

WBCs associated with allergies and parasites rather than bacterial defense.

Eosinophils

Granulocytes that stain red.

Eosinophils

Granulocytes containing granules that stain blue.

Basophils

Actively phagocytic WBCs that are important in inflammation and are formed in bone marrow.

Monocytes

The three granulocytes formed in bone-marrow sinusoids that pass through immature stages.

Neutrophils, eosinophils, and basophils

Decreased oxygen-carrying hemoglobin in peripheral blood.

Anemia

Condition producing pallor of the oral mucosa, conjunctiva, and nail beds plus fatigue, weakness, and shortness of breath.

Anemia

Anemia caused by premature RBC destruction and a shortened RBC lifespan.

Hemolytic anemia

The three major hereditary forms of hemolytic anemia.

Spherocytosis, sickle cell anemia, and thalassemia

Less common causes of hemolytic anemia involving antibodies or a parasite.

Autoimmune or allergic reactions and malaria

Hereditary hemolytic anemia in which spherical RBCs are fragile and likely to rupture.

Spherocytosis

Hereditary hemolytic anemia for which splenectomy is curative.

Spherocytosis

Hemolytic anemia caused by defective hemoglobin formation and associated with Mediterranean ancestry.

Thalassemia

Substance produced by the breakdown of hemoglobin.

Bilirubin

Hemolytic disease caused when an Rh-negative mother produces antibodies against an Rh-positive fetus, especially affecting later pregnancies.

Erythroblastosis fetalis

Hemolytic anemia involving abnormal HbS, vaso-occlusion, ischemia, and bone infarcts.

Sickle cell anemia

Anemia in children commonly complicated by osteomyelitis with lytic destruction and periosteal reaction.

Sickle cell anemia

Condition producing biconcave superior and inferior vertebral endplate indentations called fish vertebrae.

Sickle cell anemia

Condition producing multilevel central endplate depressions and H-shaped vertebrae on MRI.

Sickle cell anemia

Macrocytic anemia caused by B12 or folate deficiency and defective DNA synthesis.

Megaloblastic anemia

Type of megaloblastic anemia associated with the most common cause of vitamin B12 deficiency.

Pernicious anemia

Condition associated with gastric atrophy, a tubular bald stomach, and decreased or absent rugal folds.

Pernicious or megaloblastic anemia

Anemia caused by generalized failure of the bone marrow to function.

Aplastic anemia

Anemia associated with chemical or drug exposure, infection, or cancer invading the bone marrow.

Aplastic anemia

Simultaneous decrease in RBCs, WBCs, and platelets.

Pancytopenia

Anemia caused by infiltration of marrow with nonhematopoietic cells or encroachment caused by cortical thickening.

Myelophthisic anemia

Anemia caused by marrow replacement from disorders such as Gaucher disease, osteopetrosis, or myelofibrosis.

Myelophthisic anemia

Condition defined in the chapter as increased production of erythrocytes, granulocytes, and platelets.

Polycythemia

Primary polycythemia characterized by bone-marrow hyperplasia.

Polycythemia vera

Polycythemia caused by a long-term inadequate oxygen supply.

Secondary polycythemia

Polycythemia associated with severe pulmonary disease, cyanotic congenital heart disease, or high altitude.

Secondary polycythemia

Condition illustrated by profound obesity, severe hypoventilation, chronic hypoxia, and engorged pulmonary vessels.

Secondary polycythemia

Neoplastic proliferation of white blood cells.

Leukemia

Leukemia described by the chapter as cancer of bone marrow involving primitive WBCs.

Myelocytic leukemia

Leukemia described by the chapter as a lymphatic malignancy in which lymphocytes dramatically increase.

Lymphatic leukemia

Blood-cell changes caused when excessive leukemic WBCs crowd out normal cells.

Decreased circulating RBCs and platelets

Abrupt, rapidly progressing leukemia most common in children.

Acute lymphocytic leukemia

Acute leukemia more common in adults.

Acute myelocytic leukemia

Finding strongly associated with chronic leukemia on this test.

Splenomegaly

Neoplasm of the lymphoreticular system involving lymph nodes, spleen, or lymphoid tissue in organs.

Lymphoma

Most common radiographic finding in lymphoma.

Mediastinal lymph-node enlargement

Characteristic diagnostic cells of Hodgkin lymphoma.

Reed-Sternberg cells

Lymphoma that usually originates in lymph nodes.

Hodgkin lymphoma

Lymphoma more likely to originate in extranodal or parenchymal organs.

Non-Hodgkin lymphoma

Primary GI sites commonly involved by lymphoma.

Stomach and small bowel

Condition in which direct extension from adjacent lymph nodes can produce bone erosion.

Lymphoma

Self-limited viral disease of the lymphoreticular system caused by Epstein-Barr virus.

Infectious mononucleosis

EBV disease producing mild fever, fatigue, sore throat, and swollen lymph nodes.

Infectious mononucleosis

Disease showing elevated WBCs, atypical lymphocytes resembling monocytes, and antibodies to EBV.

Infectious mononucleosis

Sex-linked bleeding disorder caused by decreased or absent factor VIII.

Hemophilia

Bleeding disorder whose radiographic changes result primarily from recurrent hemorrhage into joints.

Hemophilia

Mass-like bone destruction caused by hemorrhage that can mimic a malignant tumor.

Pseudotumor of hemophilia

Platelet-deficiency disorder treated by the chapter as another name for thrombocytopenia.

Purpura

Three mechanisms that can cause purpura: decreased production, increased destruction, or splenic sequestration.

Platelet deficiency

Condition producing spontaneous hemorrhage in the skin, oral mucosa, and internal organs.

Purpura

Condition producing uniform, regular thickening of small-bowel mucosal folds because of hemorrhage.

Purpura