Pathophysiology Chapter 22: Disorders of Hemostasis

Study Notes

Manifestations of Impaired Oxygen Transport

Anemia results from impaired oxygen transport, leading to compensatory mechanisms
Signs and symptoms: fatigue, weakness, dyspnea, headache, faintness, pallor, tachycardia, low cardiac output, palpitations, ventricular hypertrophy

Primary Causes of Anemia

Excessive loss of red cells from bleeding
Destruction (hemolysis) of RBCs
Defective RBC production
Inadequate RBC production due to bone marrow failure

Red Blood Cell Indices

MCV (Mean Corpuscular Volume): reflects RBC size
- Microcytic: smaller than normal
- Macrocytic: larger than normal
- Normocytic: normal size
MCHC (Mean Corpuscular Hemoglobin Concentration): reflects average amount of hemoglobin in RBCs
- Normochromic: normal color
- Hypochromic: pale color

Types of Anemia

Acute Blood Loss Anemia
- Excessive loss of red cells from bleeding
- Clinical and red cell changes depend on rate of hemorrhage and whether bleeding is internal or external
- Causes circulatory collapse
Chronic Blood Loss Anemia
- Leads to iron deficiency anemia
- Asymptomatic until Hgb < 8 d/dL
- GI bleeding, menstrual disorders
- RBCs produced have too little Hgb
- Microcytic and hypochromic
Hemolytic Anemia
- Characterized by premature destruction of RBCs
- Shortened life-span
- Increased bone marrow activity
- Normocytic and normochromic
Sickle Cell Disease
- Abnormal substitution of an amino acid in hemoglobin molecules
- Inherited disorder
- Recessive disorder
- Sickle cell trait
- Sickle cell disease
- Clinical manifestations: acute pain, jaundice, vaso-occlusive crisis
Iron Deficiency Anemia
- Etiology: dietary deficiency, loss of iron through bleeding
- Impoverished populations
- Vegetarians
- GI bleeding
- Menstruation
- Pregnant women
- Microcytic and hypochromic
- Clinical manifestations: pica, spoon-shaped deformity of fingernails, glossitis, angular cheilitis, dysphagia
Megaloblastic Anemia
- Caused by impaired DNA synthesis
- MCV > 100 fL
- Impaired maturation and division
- Develops slowly
- Vitamin B12 deficiency and folic acid deficiency
Vitamin B12 Deficiency
- Essential for DNA synthesis and normal red blood cell maturation
- Risk factors: proton pump inhibitors, GI disease, gastrectomy, or gastric bypass
- Pathophysiology: vitamin B12 bound to intrinsic factor
- Clinical manifestations: mild jaundice, neurologic changes
- Macrocytic and normochromic
Folic Acid Deficiency
- Required for DNA synthesis and red cell maturation
- Etiology: dietary deficiency, alcohol abuse, celiac disease
- Clinical manifestations: similar to Vitamin B12 deficiency
- Macrocytic and normochromic
Aplastic Anemia
- Disorder of bone marrow stem cells
- Reduction of all three hematopoietic cell lines
- Pancytopenia
- Etiology: high doses of radiation, chemotherapy, chemicals, and toxins
- Clinical manifestations: fatigue, weakness, frequent infections
Chronic Disease Anemia
- Complication of chronic infections, inflammation, cancer
- Renal failure
- Kidneys are primary site for erythropoietin
- Clinical manifestations: fatigue, weakness, pallor

Polycythemia

Abnormally high total red blood cell mass
Increased RBC count, hemoglobin, and hematocrit
Increased blood volume and viscosity
Clinical manifestations: hypertension, headache, dizziness, decreased cerebral blood flow, venous stasis, thromboembolism

Geriatric Considerations

HCT levels are lower after age 60
Decreased production of RBCs
Chronic illnesses, infection
Anemia in elderly is never normal
Nutrient deficiencies secondary to altered absorption, interference by medications, malabsorption

Description

This quiz covers the disorders of hemostasis, including inappropriate blood clotting and insufficient clotting to stop blood flow. It discusses the mechanisms of thrombosis and bleeding in relation to hemostasis.