1. ANEMIA DEFINITION
• According to World Health Organization criteria, anemia is defined as
blood hemoglobin (Hb) concentration <13g/dl or
hematocrit(hct)<39% in adult males; Hb< 12g/dl or Hct<37% in adult
females.
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31. • The acuteness and severity of the anemia determine whether
transfusion therapy with packed RBCs is indicated.
• Rapid occurrence of severe anemia (e.g., after acute GI hemorrhage
resulting in Hct<25%,following volume repletion) or development of
angina or other symptoms is an indication for transfusion.
• Hct should increase 3–4% [Hb by 10 g/L (1 g/dL)] with each unit of
packed RBCs, assuming no ongoing losses.
• Chronic anemia (e.g., vitamin B12 deficiency), even when severe, may
not require transfusion therapy if the pt is compensated and specific
therapy (e.g., vitamin B12) is instituted.
32. • Iron deficiency: find and treat cause of blood loss, oral iron (e.g., FeSO4 300 mg
tid).
• Folate deficiency: common in malnourished, alcoholics; less common now than
before folate food supplementation; folic acid 1 mg PO qd (5 mg qd for pts with
malabsorption).
• Vitamin B12 deficiency: can be managed either with parenteral vitamin B12 100
μg IM qd for 7 d, then 100–1000 μg IM per month or with 2 mg oral crystalline
vitamin B12 per day. An inhaled formulation is also available.
• Anemia of chronic disease: treat underlying disease; in uremia use recombinant
human erythropoietin, 50–150 U/kg three times a week; role of erythropoietin in
other forms of anemia of chronic disease is less clear; response more likely if
serum erythropoietin levels are low. Target Hb 9–10 g/dL. Iron administration is
not useful.
33. • Sickle cell anemia: hydroxyurea 10–30 mg/kg per day PO increases level of Hemoglobin F
(HbF) and prevents sickling, treat infections early, supplemental folic acid; painful crises
treated with oxygen, analgesics (opioids), hydration, and hypertransfusion; consider
allogeneic bone marrow transplantation in pts with increasing frequency of crises.
• Thalassemia: transfusion to maintain Hb >90 g/L (>9 g/dL), folic acid, prevention of Fe
overload with deferoxamine (parenteral) or deferasirox (oral) chelation; consider
splenectomy and allogeneic bone marrow transplantation.
• Aplastic anemia: antithymocyte globulin and cyclosporine leads to improvement in 70%,
bone marrow transplantation in young pts with a matched donor.
• Autoimmune hemolysis: glucocorticoids, sometimes immunosuppressive agents,
danazol, plasmapheresis, rituximab.
• G6PD deficiency: avoid agents known to precipitate hemolysis
