Microcytic Anemias

Iron deficiency (NE/M 1999:341 1986)

• i marrow iron — 4 heme synthesis — microcytosis — anemia

• Special clinical manifestations: angular cheilosis, atrophic glossitis, pica (consumption of nonnutritive substances such as ice. clay), koilonychia (nail spooning)

Plummer-Vinson syndrome (iron deficiency anemia, esophageal web & atrophic glossitis)

• Etiologies: chronic bleeding (Gl. menstrual, etc.). 4 supply (malnutrition; 4 absorp. due to celiac sprue. Crohn's. * gastric pH. subtotal gastrectomy), t demand (preg.. epo)

• Diagnosis: 4 Fe. tTIBC.4 ferritin (espec 15). 4 Fe/TIBC (espec. 15%). * soluble transferrin receptor; * pit; unless history c w a different etiology, initiate workup for GIB

• Treatment: Fe supplementation ( 6 wks to cornea anemia; 6 mos to replete Fe stores)

Thalassemias (nejm 2005:353 1135)

• I synthesis of a- or p-globin chains of Hb • / subunits — destruction of RBCs and erythroid precursors;.. anemia from hemolysis and ineffective erythropoiesis

• a-thalassemia: deletions in a-globin gene complex on chr. 16 (nl 4 a genes)

3 c*— a-thal-2 trait silent carrier; 2 a-» a-thai-1 trait or u-thal minor mild anemia 1a-» HbH ({$«) disease severe anemia, hemolysis, and splenomegaly | 0 a genes Hb Barts (74) intrauterine hypoxia and hydrops fetalis

• ^-thalassemia: mutations in |i-globin gene on chr. 11 — absent or 4 gene product

1 mutated gene — thai minor mild anemia (no transfusions)

2 mutated (J genes thai intermedia (occasional transfusions) or thai major ( Cooleys anemia; transfusion-dependent) depending on severity of mutations

I • Special clinical manifestations (in severe cases): chipmunk fades, pathologic fractures, hepatosplenomegaly. high-output CHF. bilirubin gallstones, iron overload syndromes (from chronic transfusions) | • Diagnosis: MCV 70. normal Fe. MCV/RBC count <13. • * retics. basophilic stippling; Hb electrophoresis: T HbAj (ajfij) in |4-thal; normal pattern in a-thal trait

• Treatment: folate: transfusions - deferoxamine, deferasirox (oral iron chelator);

splenectomy if ¿50% ? in transfusions; consider allogeneic HSCT in children w severe p-thal major

Anemia of chronic inflammation (ACI; nejm 2005:3511011)

• Impaired iron utilization & 1 epo-responsiveness due to t hepcidin & cytokines in setting of autoimmune disorders, chronic infection, inflammation. HIV. malignancy

• Dx: 4 Fe. 4TIBC. ± t ferritin; usually normocytic but can be microcytic if prolonged

• ACI w Fe-deficiency anemia: soluble transferrin receptor (sTFR) T in Fe deficiency sTFR log Ferritin: >2 — ACI w Fe deficiency; <1 -»ACI alone (Blood 1997:89 1052)

• Treatment: treat underlying disease • erythropoietin; for cancer- or chemo-related use epo for goal Hb 10-12 (11-12 if sx) g dl. Iron if ferritin -100 or Fe TIBC - 20% Sideroblastic anemia

• Defective heme biosynthesis within RBC precursors

• Etiologies: hereditary, idiopathic (MDS). reversible (alcohol, lead, isoniazid.

chloramphenicol, copper deficiency, hypothermia)

• Special clinical manifestations: hepatosplenomegaly. iron overload syndromes

• Diagnosis: can be micro-, normo-. or macrocytic: variable population of hypochromic RBCs;

T Fe. normal TIBC.! ferritin, basophilic stippling. RBC Pappenheimer bodies (iron-containing inclusions), ringed sideroblasts (with iron-laden mitochondria) in BM

• Treatment: treat reversible causes; supportive transfusions for severe anemia; high-dose pyridoxine for some hereditary cases

Figure 5-2 Approach to microcytic ancmui

Microcytic Anemia

4 ferritin Fe/TIBC <18% MCV/RBC >13

Iron deficiency normal iron studies

MCV/RBC <13 basophilic stippling : T retics t abnl Hb electro. +

Thalassemia

T Fe, nl TIBC t ferritin basoph.lic stippling nnged sideroblasts in BM

Sideroblastic chronic inflammation

Was this article helpful?

0 0

Post a comment