Anemia
General Characterisctics Definition: anemia is a decrease in red blood cells. Happens due to underproduction, increased destruction or loss of red cells. Diagnosis of anemia: Hgb < 135 (men) Hgb <120 (women) Reticulocyte count is a value that reflects a level of RBC production. Low Retic count indicates underproduction and elevated retic count indicates increased destruction or blood loss
General Characteristics Clinical Presentation: symptoms originate from decreased oxygen delivery such as fatigue and exertional dyspnea, dizziness Signs include pallor, tachycardia, orthodontic hypotension Other signs and symptoms are related to specific causes of anemia
Diagnosis Low retic Underproduction Low MCV Normal MCV High MCV Microcytic anemia Normocytic anemia Macrocytic Anemia
Diagnosis High Retic Increased Destruction or blood loss Increased LDH, bilirubin. Decreased haptoglobin S/s bleeding Hemolysis Acute blood loss
Microcytic Anemias (Low retic, low MCV)
Iron Deficiency Definition: Iron deficiency is the most common cause of anemia. Low levels of serum iron and iron stores resulting in decreased RBC production. Etiology: Underlying cause of iron deficiency must be identified Menstrual blood loss and pregnancy are the most common causes of iron deficiency GI blood loss is most common in all other patients Diagnosis: low Hgb, retic, MCV, serum ferritin and iron. TIBC is increased Tx: supplement iron and treating the underlying cause
Thalassemia Definition: It is an inherited trait causing decreased production of either alpha or beta globin chains resulting in destruction of RBCs and a microcytic anemia. The anemia is caused by both hemolysis and decreased production of RBCs. Hydrops fatalis is the most severe form of alpha thalassemia and is incompatible with life. Diagnosis: iron studies=normal, microcytic anemia (low Hgb, retic and MCV) with poikiloctes, target cells and uncleared RBCs on the peripheral smear. Hgb electrophoresis is definitive test for beta thalassemia. analysis shows elevated Hgb A2 and/or Hgb F. Alpha thalassemia is diagnosed using the alpha globin gene analysis Treatment: transfusions and chelation therapy as needed for iron overload. Splenectomy and stem cell transplant may be considered in very severe cases.
Sideroblastic Definition: sideroblastic anemia is a disorder with abnormal iron metabolism resulting in sideroblasts seen on peripheral smear or in the bone marrow. Etiology: hereditary, lead poisoning, ETOH, copper deficiency, hypothermia, MDS. Diagnosis: CBC shows microcytic anemia, increased serum ferritin and iron. Diagnosis: Bone marrow bx shows ringed sideroblasts and basophilic stippling. Treatment: correct the underlying cause. Pyridoxine 50-200mg PO daily for some hereditary causes. Supportive transfusions.
Normocytic Anemias (Low Retic, normal MCV)
Anemia of Chronic Disease Definition: An anemia associated with a chronic disease such as an autoimmune disease, chronic infection or inflammatory disease. It is often normocytic but can be microcytic. Diagnosis: Diagnosis of Exclusion! CBC shows normochromic normocytic anemia with a normal peripheral smear. serum iron and TIBC may be low. Ferritin can be normal or elevated as an acute phase reactant. EPO (erythropoietin) may be low especially in chronic kidney disease. Treatment: treat underlying chronic disease. If EPO is low, supplement.
Macrocytic Anemia (Low Retic, High MCV)
Megaloblastic Anemia Definition: Composed of 2 main types: folic acid deficiency and B12 deficiency Results in impaired DNA synthesis and ineffective erythropoesis and macrocytosis due to one of the above deficiencies.
B12 Deficiency Etiology: dietary deficiency, pernicious anemia, gastrectomy, chronic pancreatitis, ileal resection Clinical Presentation: glossitis, numbness, paresthesias, decreased vibratory and positional sense, dementia Diagnosis: CBC shows microcytic anemia, decreased retic, increased MCV, deceased B12 Treatment: 1mg B12 IM q weekly or q monthly depending on severity until normalization of Hgb. Long term therapy is B12 IM q month. Of note: coexistence of iron deficiency occurs in 1/3 of cases
Folate Deficiency Etiology: decreased intake, ETOH, malabsorption, pregnancy, medications (methotrexate, sulfasalazine, anticonvulsants) Diagnosis: decreased Hgb, decreased Retic, increased MCV, decreased folate Treatment: folic acid 1mg PO daily until Hgb and folic acid levels corrected. High dose folic acid may be used for severe malabsorption cases.
Non-megaloblastic Etiology: liver disease, ETOH, hypothyroidism, MDS, medications that impair DNA synthesis such as hydroxyurea and 5-FU Diagnosis shows typical macrocytosis anemia but normal folate and B12 levels Treatment: treat the underlying cause, stop the offending medication
Hemolytic Anemias (Low Hgb, High Retic)
General Characteristics Categorized by the site of hemolysis: intrinsic or extrinsic Intrinsic: hemolysis occurs intravascularly. Causes include incompatible blood transfusion, hemaglobinopathies, cold agglutinin disease, malaria Extrinsic: hemolysis occurs in the reticuloendothelial system- usually the spleen. The cause is often immune mediated.
G6PD Deficiency Definition: G6PD is an intrinsic hemolysis. It is an X linked enzyme deficiency on glucose-6-phosphate dehydrogenase. Etiology: Hemolysis can be precipitated by eating fava beans, infections or medications. Diagnosis: CBC shows low Hgb and smear shows Heinz bodies/bite cells. Low G6PD levels is the hallmark for diagnosis. Treatment: avoid instigating medication or fava beans. Transfusions given as needed.
Sickle Cell Disease Definition: Single amino acid substitution at position 6 in beta globin chain causing RBCs to sickle resulting in hemolysis and micro-vascular occlusion. Clinical presentation: vaso-occlusive symptoms (acute chest pain, pain crises, CVA) and infarction. Diagnosis: normocytic anemia, high Retic, neutrophilia. Peripheral smear shows sickle cells. Definitive diagnosis: made with Hgb electrophoresis. Treatment: hydroxyurea and supportive care with hydration, oxygen, analgesia, transfusions.
Hereditary Spherocytosis Definition: A defect in a protein of the RBC membrane. Clinical presentation: patients present with anemia, jaundice, and splenomegaly. Diagnosis: CBC shows anemia, high Retic, positive osmotic fragility test makes the definitive diagnosis. Treatment: folate supplementation and splenectomy.
Autoimmune Hemolytic Anemia Definition: acquired auto-immune RBC destruction Two main types: warm and cold Warm: IgG antibodies destroy RBCs. Etiology: medications, malignancy, most commonly idiopathic. Cold: IgM antibodies bind to RBCs at temperatures below 37C causing complement fixation and Intravascular hemolysis with cold exposure. Diagnosis: anemia with positive direct antiglobalization test (DAT) or Coomb's test. Cold agglutinin titers will confirm the type of autoimmune hemolytic anemia. Treatment: corticosteroids, IVIG, Rituximab, splenectomy. Treatment is based on severity