Anemia

Anemia is defined as a hemoglobin <13.5 g/dL in men or <12.0 g/dL in women. Etiologies are categorized by decreased RBC production, increased RBC destruction, and/or blood loss. Evaluation of anemia begins with an assessment of the MCV to distinguish microcytic (MCV <80), normocytic (MCV 80–100), and macrocytic (MCV>100) anemias. MCHC is used to distinguish hypochromic (<33), normochromic (33–35), and hyperchromic (>35) anemia.

Differential Diagnosis

Microcytic

• Iron deficiency
  –Most common cause of anemia
  –Due to chronic blood loss (e.g., menstrual, GI bleeding, frequent blood donation)
• Sideroblastic anemia
• Lead poisoning
• Thalassemia
• Anemia of chronic disease (often late)
  Macrocytic
• Vitamin B₁₂ or folate deficiency
  –Malabsorption
  –Poor dietary intake
  –Pernicious anemia
  –Alcohol abuse
• Liver disease
• Alcohol and medications (e.g., chemotherapeutics, HIV medications)
• Hypothyroidism
• HIV
• Myelodysplastic syndrome
• Acute leukemia
• Reticulocytosis (e.g., hemolytic anemia, production of RBCs in response to blood loss and/or vitamin B₁₂ or iron repletion)

Normocytic
• Hemorrhage, blood loss
• Anemia of chronic disease
  –Renal disease (due to decreased erythropoietin production)
  –Hypometabolic states (e.g., protein malnutrition, hypothyroidism)
• Infection
• Hemolysis (drug-induced, autoimmune, SLE, G-6PD deficiency)
• Bone marrow disease
  –Aplastic anemia
  –Bone marrow invasion (e.g., malignancy)
• Hypothyroidism
• Renal insufficiency
• Sickle cell disease
• Microangiopathy
• Membrane defects (e.g., hereditary spherocytosis)
• Disseminated intravascular coagulation
• Thrombotic thrombocytopenic purpura

Workup and Diagnosis

• Detailed history and physical examination
  –History of bleeding, past history of anemia, family history
  –Vital signs, including orthostatic blood pressure/pulse
  –Include rectal and stool guaiac
• Initial laboratory studies include CBC with red cell indices (MCV, MCHC, RDW), peripheral smear (may show characteristic cell types such as spherocytes, schistocytes, multinucleated cells), and reticulocyte count (increased if anemia is due to blood loss or RBC destruction; decreased if due to marrow failure)
• Further studies may include iron panel (iron, ferritin, transferrin saturation, TIBC), haptoglobin, vitamin B₁₂ and folate levels, bilirubin, LDH, LFTs, TSH, renal function, hemoglobin electrophoresis, bone marrow aspirate, GI workup
• Etiology may be classified based on laboratory results
  –Iron deficiency: Decreased ferritin, reticulocytes, MCV, and MCH; increased TIBC
  –Chronic disease: Decreased reticulocytes and TIBC; normal MCV and MCH
  –B₁₂ and/or folate deficiency: Decreased reticulocytes; increased MCV
  –Marrow failure: Decreased reticulocytes; may involve other cell lines
  –Hemolysis: Increased reticulocytes, bilirubin, and LDH; decreased haptoglobin in cases of intravascular hemolysis

Treatment

• Severe cases of anemia require immediate intervention if hemodynamic compromise occurs
• Administer supplemental O₂ as needed
• In cases of ongoing acute blood loss, establish two large-bore IVs; monitor and send for blood type and cross
• IV fluids as necessary to maintain blood pressure
• Blood transfusion is generally indicated for Hb <8
  –Young, healthy patients should only be transfused if symptomatic or have ongoing acute blood losses
  –Cardiac patients may require transfusion at Hb <10
  –Avoid transfusing beyond Hb >12, as this may increase blood viscosity and impair O₂ delivery
• Supplement vitamin B₁₂, folate, and iron as necessary
• Patients with primary marrow disorders require transfusions, further evaluation, and possibly a bone marrow transplant
• Treat underlying disease according to established protocols

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

Other Book Chapters Related to Anemia

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Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

More About Causes of Anemia

• Back to symptom: Anemia: Introduction (review 810 causes)
• Next Book Extract About Anemia: Fatigue (In A Page: Pediatric Signs and Symptoms)
• All Book Extracts: All Online Book Extracts for Anemia

More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

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• ANEMIA (Differential Diagnosis in Primary Care)
• PALLOR OF THE FACE, NAILS, OR CONJUNCTIVA (Differential Diagnosis in Primary Care)

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