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microcytic anemia

Anemia with low erythrocyte mean corpuscular volume (MCV). Etiology: 1) iron-deficiency anemia a) chronic blood loss b) iron-poor diet c) celiac disease 2) anemia of chronic disease, chronic inflammation 3) lead poisoning 4) hyperthyroidism (occasional) 5) genetic defects (some may be acquired)* a) hemolysis* b) thalassemia c) some hemoglobinopathies d) sideroblastic anemia* Genetics: - defects in SLC11A2 are a cause of hypochromic microcytic anemia Laboratory: 1) complete blood count (CBC) with differential a) anemia: RBC count 1] < 5 x 10E12/L in Fe deficiency 2] > 5 x 10E12/L in thalassemia b) RDW 1] > 16 in Fe deficiency 2] < 16 in thalassemia c) microcytosis d) microcytic anemia in menstruating woman precludes need to prove iron deficiency provided normal prior blood hemoglobin (MKSAP19) 3) reticulocyte count 3) iron studies a) serum iron b) total iron-binding capacity (TIBC) c) serum ferritin d) transferrin saturation 1] measured by serum iron/total-iron binding capacity (TIBC) 2] <10% is consistent with iron deficiency 3] >15% is consistent with anemia of chronic disease 4] 10-15% indicates a bone marrow biopsy to distinguish iron deficiency from anemia of chronic disease 4) peripheral smear 5) fecal occult blood 6) blood lead level 7) low serum erythropoietin level confirms hypoplastic marrow 8) hemoglobin electrophoresis a) target cells, sickle cells on peripheral smear b) splenomegaly c) evidence of bone remodelling d) hemoglobinopathy e) beta-thalassemia 1] hemoglobin A2 3-7% in beta-thalassemia minor 2] hemoglobin A2 7-90% in beta-thalassemia major 9) free erythrocyte (zinc) protoporphyrin (FEP) a) increased in: 1] iron deficiency 2] anemia of chronic disease 3] heavy metal exposure b) normal in: 1] thalassemia 2] sideroblastic anemia 10) bone marrow biopsy if indicated a) leukopenia b) thrombocytopenia c) myelocytes d) nucleated erythrocytes e) lymphadenopathy f) splenomegaly Special laboratory: 1) upper GI endoscopy a) suspicion of upper GI bleed b) telangiectasias (hereditary hemorrhagic telangiectasias) [4] 2) colonoscopy for positive fecal occult blood Management: 1) treat specific etiology 2) see anemia

Interactions

disease interactions

Related

anemia of chronic disease (ACD) hemoglobinopathy hypochromic anemia mean corpuscular volume (MCV)

Specific

iron-deficiency anemia thalassemia

General

anemia microcytosis

Database Correlations

OMIM 206100

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 572-74
  2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 409-415
  3. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  4. Medical Knowledge Self Assessment Program (MKSAP) 14, 16, American College of Physicians, Philadelphia 2006, 2012 - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  5. Jain S, Kamat D. Evaluation of microcytic anemia. Clin Pediatr (Phila). 2009 Jan;48(1):7-13. PMID: 18832550
  6. DeLoughery TG et al Microcytic Anemia N Engl J Med 2014; 371:1324-1331. October 2, 2014 PMID: 25271605 http://www.nejm.org/doi/full/10.1056/NEJMra1215361
  7. ARUP consult: Microcytic Anemia Testing Algorithm https://arupconsult.com/algorithm/microcytic-anemia-testing-algorithm