Diagnosis

Anemia

Etiology

Etiology of decreased production [2kz]

1. Hypoproliferative Microcytic Anemia (corrected reticulocyte <2%, MCV<80)

   • Iron deficiency anemia / Malnutrition

   • Anemia of chronic disease (inflammatory inhibition through cytokines)

   • Sideroblastic anemia

   • Thalassemia

   • Lead poisoning 

2. Hypoproliferative Normocytic Anemia (corrected reticulocyte <2%, MCV 80-100)

   • Anemia of chronic disease (inflammatory inhibition through cytokines)

   • Renal failure (low on EPO stimuli)

   • Bone marrow failure (Leukemia, Lymphoma, Myelofibrosis, Myelodysplasia, Aplasia)

   • Pure red cell aplasia

   • Myelofibrosis or myelophthisic processes

   • Multiple myeloma

3. Hypoproliferative Macrocytic Anemia (corrected reticulocyte <2%, MCV>100)

   • Alcohol

   • Liver disease

   • Hypothyroidism (low on thyroxin stimuli)

   • Folate and Vitamin B12 deficiency

   • Myelodysplastic syndrome

   • Drug-induced

     • Diuretics 

     • Chemotherapeutic agents

     • Hypoglycemic agents

     • Antiretroviral agents

     • Antimicrobials

     • Anticonvulsants

Etiology of hemolytic anemia [2kz]

reticulocyte count is > 2%, elevated LD, decreased haptoglobin

• Extravascular hemolysis: RBC prematurely destroyed by the liver and spleen

  • Hemoglobinopathies (sickle cell, thalassemia)

  • Enzyemopathies (G6PD deficiency, pyruvate kinase deficiency)

  • Membrane defects (hereditary spherocytosis, hereditary elliptocytosis)

  • Drug-induced

• Intravascular hemolysis: red cells lyse within the circulation, and is less common. 

  • Paroxysmal nocturnal hemoglobinuri

  • Autoimmune hemolytic anemia (idiopatic, lymphoma, SLE, infection, drugs, transfusion -> Coombs test)

  • Transfusion reactions

  • Microangiopathic hemolytic anemia

  • Disseminated Intravascular Coagulation

  • Infections

  • Snake bites/venom

Physical etiologies

• Traumatic hemorrhage

• Burns

• Frostbite

• Prosthetic valves and surfaces

• Pregnancy

Infectious etiologies

• Viral - Hepatitis, Mononucleosis, cytomegalovirus

• Bacterial - Clostridia, gram-negative sepsis

• Protozoal - Malaria, leishmaniasis, toxoplasmosis, hookworm (GI loss), schistosomiasis (urinary loss)

Genetic etiologies

• Hemoglobinopathies (Sickle cell anemia, Thalassemia -> decreased MCV/ferritin)

• Enzyme abnormalities (Glucose-6-ph Dehydrogenase, Pyruvate kinase, Paroxysmal nocturnal hemoglobinuri)

• Defects of the RBC cytoskeleton Sspherocytosis)

• Congenital dyserythropoietic anemia

• Rh null disease

• Hereditary xerocytosis

• Abetalipoproteinemia

• Fanconi anemia

Pathophysiology

• Decrease in intravascular volume -> hypovolemia -> hypotension -> baroreceptor in carotid bulb -> sympathetic stimuli -> adrenaline/ADH/renin/angiotensin -> tachycardia, increased cardiac stroke volume, vasoconstriction and decreased urine output

Epidemiology

Incidence per 100.000 [4ce]

Prevalence per 100.000 [4ce]

Approach

1. Blood test: MCV, Ferritin, B12, Folic acid, Lactic dehydrogenase, Haptoglobin [2kz]

2. Corrected reticulocyte count = percent reticulocytes x (patient's HCT/normal HCT)

   • If > 2: hemolysis or acute blood loss

   • If < 2: hypoproliferation

3. MCV:

   • MCV <80

   • MCV 90-100

   • MCV >100

4. Other tests based on reticulocytes and MCV:

   • Hemofec

   • Urine stix: hematuria

   • Coombs test

   • Blood smear

   • Coloscopy in elders

Treatment

1. Acute treatment of anemia:

   • IV fluids, crossmatched blood transfusions, oxygen

   • Maintain hemoglobin > 7 g/dL (> 8 g/dL if cardiovascular disease)

2. Treatment of the underlying cause

   • Nutritional deficiencies: Oral/IV iron, B12, and folate

   • Chronic disease

   • Hemolytic anemia: mechanical valve replacement, discontinue medication, splenectomy, exchange transfusions (hemoglobinopathies), antifibrinolytic agents (DIC)

Differential diagnoses

Aplastic anemia, Colorectal cancer, Folic acid deficiency, Hemolytic anemia, Hypothyroidism, Hypovolemia, Paroxysmal nocturnal hemoglobinuria, Shock, Sickle cell disease, Systemic lupus erythematosus, Thalassemia, Vitamin B12 deficiency