Blood Disorders & Hematopoiesis: Types, Causes, and Manifestations

Hematopoiesis

Production and development of blood cells from stem cells in bone marrow.

Blood Disorders

Disorders due to defects in blood cell development or function.

Requirements for RBC production

Protein, iron, folic acid, vitamin B12; deficiencies cause anemia.

Anemia (definition)

Deficiency or functional abnormality of RBCs or hemoglobin; decreased RBCs, Hgb, and Hct.

Causes of anemia

Impaired RBC production, increased RBC destruction, acute or chronic blood loss.

Normocytic anemia

RBCs normal size.

Microcytic anemia

RBCs abnormally small.

Macrocytic anemia

RBCs abnormally large.

Normochromic anemia

Normal hemoglobin content.

Hypochromic anemia

Reduced hemoglobin content.

Iron-deficiency anemia (type)

Microcytic-hypochromic anemia; most common worldwide.

Causes of iron-deficiency anemia

Poor intake, impaired duodenal absorption, pregnancy, chronic blood loss.

Pathophysiology of iron-deficiency anemia

Depleted iron stores → decreased circulating iron → impaired Hgb/myoglobin → reduced oxygen-carrying capacity.

Manifestations of iron-deficiency anemia

Low Hgb/Hct, pale skin, fatigue, dyspnea, chest pain, brittle/spoon nails, decreased serum iron.

Pernicious anemia (type)

Macrocytic-normochromic anemia caused by vitamin B12 or intrinsic factor deficiency.

Causes of pernicious anemia

Vitamin B12 deficiency, intrinsic factor deficiency.

Pathophysiology of pernicious anemia

Impaired DNA synthesis → poor RBC production → decreased oxygen transport → nerve demyelination.

Manifestations of pernicious anemia

Megaloblasts, GI inflammation, fatigue, paresthesias, sore tongue, jaundice, enlarged spleen/liver, CHF.

Folate deficiency anemia (type)

Macrocytic-normochromic anemia due to folate deficiency.

Causes of folate deficiency anemia

Alcoholism, fad diets, low vegetable intake.

Pathophysiology of folate deficiency anemia

Folate deficiency → decreased RBC synthesis.

Manifestations of folate deficiency anemia

Cheilosis, stomatitis, oral ulcers, dysphagia, watery diarrhea.

Sickle cell anemia (type)

Normocytic-normochromic anemia caused by genetic mutation producing Hemoglobin S.

Cause of sickle cell anemia

Genetic mutation replacing glutamic acid with valine.

Pathophysiology of sickle cell anemia

HbS → deoxygenation → RBC sickling → rigid, elongated RBCs → vaso-occlusion.

Manifestations of sickle cell anemia

Sickle-shaped RBCs, severe anemia, swollen hands/feet, bone pain, jaundice, recurrent crises.

Thalassemias (type)

Microcytic-hypochromic anemia due to defective α or β globin chain synthesis.

Causes of thalassemia

Autosomal recessive disorder causing defective globin chain synthesis.

Pathophysiology of thalassemia

Impaired α/β chain → decreased Hgb → buildup of unpaired chains → RBC destruction.

Manifestations of thalassemia

Bronze skin, facial bone prominence, severe anemia, splenomegaly, hepatomegaly, CHF.

Leukemia (definition)

Malignant neoplasm of WBCs that originates in bone marrow and spreads to lymph tissues.

Classification of leukemia

ALL, CLL, AML, CML.

Acute leukemia characteristics

Poorly differentiated blast cells; rapid progression.

Chronic leukemia characteristics

Well-differentiated cells; slow progression.

Acute Lymphoblastic Leukemia (ALL)

Most common childhood cancer; rapid proliferation of immature lymphoblasts.

Pathophysiology of ALL

Excess lymphoblasts crowd out normal cells; nonfunctional leukemic cells enter blood/lymph.

Manifestations of ALL

Pale skin, fatigue, fever, bone pain, bruising, lymphadenopathy, hepatosplenomegaly, headaches, leukostasis.

Chronic Lymphocytic Leukemia (CLL)

Gradual production of malignant B lymphocytes.

Pathophysiology of CLL

Malignant B cells fail to produce antibodies; autoimmune destruction of RBCs possible.

Manifestations of CLL

Fatigue, lymph node enlargement, hepatosplenomegaly, B-cell deficiencies, anemia, low platelets.

Acute Myelogenous Leukemia (AML)

Cancer of myeloid line; similar symptoms to ALL.

Chronic Myelogenous Leukemia (CML)

Myeloid cancer associated with Philadelphia chromosome (22 & 9 translocation).

Pathophysiology of CML

Chronic phase progresses to blastic phase resembling acute leukemia.

Manifestations of CML

Fatigue, weight loss, fever, night sweats, hyperuricemia, gout, hepatosplenomegaly.

Hodgkin Lymphoma

Cancer of lymph nodes with Reed-Sternberg cells.

Causes of Hodgkin lymphoma

EBV association, genetic disorders.

Pathophysiology of Hodgkin lymphoma

Spreads from one lymph node group to the next; RS cells; B/T-cell defects.

Manifestations of Hodgkin lymphoma

Localized lymph node enlargement, fever, weight loss, fatigue, infection susceptibility.

Non-Hodgkin Lymphoma

Lymphoid cancer WITHOUT Reed-Sternberg cells.

Causes of Non-Hodgkin lymphoma

Genetic disorders, infections, environmental exposures, immunodeficiencies.

Pathophysiology of Non-Hodgkin lymphoma

Chromosomal translocation; B, T, or NK-cell defects.

Manifestations of Non-Hodgkin lymphoma

Multiple peripheral lymph node enlargements.

Multiple Myeloma

B-cell cancer causing excess immunoglobulin production and bone destruction.

Pathophysiology of Multiple Myeloma

Malignant plasma cells produce abnormal IgG, infiltrate bone, form tumors.

Manifestations of Multiple Myeloma

Hypercalcemia, bone/back pain, anemia, infections, free immunoglobulins in blood/urine.

Polycythemia Vera (PV)

Excessive production of RBCs, WBCs, and platelets.

Causes of PV

Increased sensitivity to growth factors; hereditary tendency.

Pathophysiology of PV

Increased blood viscosity → engorged vessels → slow flow → decreased perfusion → hypercoagulable state.

Manifestations of PV

Headache, hypertension, vessel distension, hepatosplenomegaly, plethora, erythromelalgia, inappropriate clotting (DVT).