Approach to Anemia
Anemia is a disorder of the red blood cell. Anemia is present when there is a decreased level of hemoglobin in the blood below the reference level for the age, sex and pregnancy state of the individual. Symptoms
Depends on acuteness and severity of anemia. Symptoms can occur when anemia is chronic, however most patients are asymptomatic. Symptoms which relate to the underlying cause include non-specific complaints such as fatigue, headache, faintness, dyspnea, palpitations, intermittent claudication, tinnitus.
Physical Exam Findings
- General: pallor of mucus membranes, signs of hyperdynamic circulation (tachycardia, bounding pulse, cardiomegaly, and systolic flow murmur), heart failure, orthostatic hypotension
- Specific: koilonychia (ridging and spoon shape nails in iron deficiency anemia), jaundice (hemolytic anemia), bone deformities (thalassemia), leg ulcers (sickle cell disease), splenomegaly, petechaie/purpura (bleeding disorder), glossitis (iron, folate, vitamin B12 deficiencies), neurologic abnormalities (vitamin B12 deficiency)
Classification of Etiologies
|
Decreased production
Nutritional deficiencies
-iron deficiency
-vitamin B12 deficiency
-folate deficiency
Bone marrow suppression
-Infections: HIV, tuberculosis, malaria, hepatitis
-Drugs: Isoniazid, chloramphenicol, alcohol, zidovudine, 5-FU, hydroxyurea
-Chronic disease: renal and liver disease, rheumatologic diseases, hypothyroidism
Hemoglobinopathies
-Thalassemias
|
Increased destruction or loss
Blood loss
-acute or chronic GI bleeding
-menstrual bleeding
-trauma
Hemolysis
-Malaria
-G6PD deficiency
-Microangiopathic hemolytic anemia: TTP, HUS, DIC, eclampsia, HELLP
-Hereditary spherocytosis
-Autoimmune hemolytic anemia
-Sickle cell disease
-Hypersplenism
|
Laboratory Findings
1. Red cell values: vary according to age, sex, pregnancy state
Normal hemoglobin in men 13-18 g/dl normal MCV 76-96
Normal hemoglobin in women 11.5 -16.5 normal MCV 76-96
In adults, severe anemia is defined by a hemoglobin of < 7 g/dL.
2. Leukocyte and platelet counts: distinguish isolated anemia from pancytopenia. If pancytopenia, bone marrow aspiration/biopsy should be considered as the problem is usually in the bone marrow.
3. Reticulocyte count: Increases with the severity of the anemia, as in chronic hemolysis. A lower reticulocyte index in the face of anemia suggests: impaired bone marrow function, deficiency of iron, vitamin b12 or folate; lack of erythropoietin (renal failure); ineffective erythropoiesis
4. Peripheral Blood smear: very useful in pointing towards specific types of anemia.
Classification of anemia by red cell size
Microcytic anemia
- Iron deficiency anemia: most common worldwide. Clinically: brittle nails, atrophy of papillae of tongue, brittle hair. Etiology: poor diet, chronic blood loss (schistosomiasis, worms, GI loss from esophageal varices, peptic ulcer). Diagnosis: MCV < 80, blood smear shows hypochromic red cells, pencil shaped (poikilocytosis), target cells. Treatment: iron replacement ferrous sulfate 200 mg tds
- Anemia of chronic disease: associated with chronic inflammatory or malignant disease. Etiologies: infectious (TB, lung abscess, pneumonia, endocarditis) or non-infectious (rheumatoid arthritis, lupus), malignancy. Clinical features: normocytic anemia, reduced serum iron and TIBC, normal or raised ferritin. Treatment is treat underlying cause.
- Thalassemia: heterogeneous group of genetic disorders which result from a reduced rate of synthesis of alpha (4 chains) or beta chains (2 chains) of hemoglobin. Changes in normal ratio results in each of the disorders. Thalassemia minor: often asymptomatic. Beta thalassemia major: autosomal recessive, presents with hepatosplenomegaly, bone expansion, infections. Diagnosis; severe hypochromic microcytic anemia with raised reticulocyte count, target cells
Normocytic Anemia
- Anemia of chronic disease: see above
- Hypothyroidism: treatment is thyroid replacement
- Acute blood loss: can be normocytic before iron stores are reduced
Macrocytic Anemia:
- Vitamin B12 deficiency: Etiologies include malnutrition (alcoholics, vegetarians), pernicious anemia, decreased absorption (celiac sprue, Crohn’s disease), increased competition (fish tapeworm, intestinal bacterial overgrowth). Clinical features neurologic changes (numbness, paresthesia, decreased vibratory and positional sense, and ataxia). Smear shows hypersegmented neutrophils. Treatment: replacement of B12
- Folate deficiency: Etiologies include malnutrition (alcoholics, elderly), decreased absorption (sprue), impaired metabolism (methotrexate, trimethoprim, antimalarials). Treatment: folate repletion
- Hemolytic Anemia: See table for etiologies
- Due to red cell destruction and increased red cell turnover. Bone marrow is able to compensate 5 times the normal rate. Clinical features: jaundice, hepatosplenomegaly, dark urine. Labs: increased reticulocyte count, indirect hyperbilirubinemia, shistocytes on blood smear. Treatment: treatment underlying cause of hemolysis
Approach to Anemia
1. Obtain a thorough history: menstrual history, bleeding tendencies, hematuria, rectal bleeding, melena.
2. Check CBC, MCV, peripheral blood smear, bone marrow examination
3. Consider colonoscopy/endoscopy, urinalysis/ urine cytology for hematuria, pelvic ultrasound for fibroids.
4. Treatment of the cause
5. Packed red blood cells transfusion
- Consider blood transfusion (BT) if hemoglobin < 7 g/dL and patient is symptomatic
- If the patient has signs of heart failure due to anemia
- Acute blood loss and hemodynamically unstable or very symptomatic
6. Patients with anemia may have an intolerance to exercise and may fatigue quickly. PT's should be mindful of this and gradually work up to moderate levels of exercise with frequent rest breaks.
