Microcytic anemia Notes

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Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Microcytic anemia essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Microcytic anemia by visiting the associated Learn Page.
NOTES NOTES MICROCYTIC ANEMIA GENERALLY, WHAT IS IT? PATHOLOGY & CAUSES ▪ Inherited/acquired anemias, small erythrocytes, varying hemoglobin content SIGNS & SYMPTOMS ▪ Decreased oxygen to tissues → fatigue, pallor, dyspnea, activity intolerance MNEMONIC: Find Those Small Cells Last DIAGNOSIS LAB RESULTS ▪ Complete blood count (CBC), peripheral blood smear analysis, blood chemistry, iron studies TREATMENT OTHER INTERVENTIONS ▪ Nutrient replacement, packed red blood cell transfusions Microcytic anemias Fe deficiency Thalassemia Sideroblastic Chronic disease Lead poisoning OSMOSIS.ORG 415
IRON-DEFICIENCY ANEMIA osms.it/iron-deficiency-anemia PATHOLOGY & CAUSES ▪ Microcytic, hypochromic anemia, small erythrocytes, decreased hemoglobin ▪ Insufficient iron → decreased iron for hemoglobin synthesis → impaired erythropoiesis → production of microcytic, hypochromic erythrocytes ▫ Insufficient iron to synthesize hemoglobin during erythropoiesis (most common cause of anemia worldwide) CAUSES Insufficient intake/absorption ▪ Decreased intake ▫ Eating disorders (e.g. pica, anorexia, bulimia); self-imposed dietary restrictions (e.g. vegan diet); food insecurity ▪ Decreased absorption ▫ Celiac disease, surgical resection of gastrointestinal (GI) tract, bariatric surgery, excessive dietary calcium, tannates, oxalates Increased need ▪ Increased need ▫ Pregnancy, lactation ▪ Increased growth ▫ Infants, children, adolescents Increased loss ▪ Overt blood loss ▫ Hematemesis, trauma-related hemorrhage, heavy menses, hematuria, multiple blood donations ▪ Occult ▫ GI bleed (e.g. peptic ulcer, tumor); vascular lesions (e.g. hemorrhoids); hookworm/other helminthic infections 416 OSMOSIS.ORG COMPLICATIONS ▪ High-output heart failure, angina, cardiorespiratory failure ▪ Infants, young children ▫ Impaired growth, development SIGNS & SYMPTOMS Decreased oxygen to tissues ▪ Pallor ▪ Fatigue, activity intolerance, exertional dyspnea, angina ▪ Compensatory mechanisms ▫ Palpitations, increased pulse, increased cardiac output, tachypnea, selective shunting of blood to vital organs (e.g. skin to kidneys) Effects on epithelial tissues ▪ Glossitis ▫ Smooth, “beefy red” tongue ▪ Cheilosis ▫ Scaling, fissuring; dryness; lip scaling ▪ Koilonychia ▫ Spoon-shaped, concave nails ▪ Esophageal stricture ▪ Gastric atrophy ▪ Blue sclerae ▪ Pagophagia ▫ Obsessive consumption of ice DIAGNOSIS LAB RESULTS ▪ ▪ ▪ ▪ ↓ red blood cell count Low/normal reticulocytes ↓ hemoglobin, hematocrit Hypochromic-microcytic erythrocytes ▫ Decreased: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC)
Chapter 52 Microcytic Anemias ▫ Blood smear analysis: erythrocytes with increased central pallor (> ⅓ diameter, anisocytosis (anisto = unequal), poikilocytosis (poikilo = irregular), target cells (resemble target; center stain with pallor ring, outside stain ring) ▪ Iron studies ▫ Decreased serum iron, ferritin (stores cellular iron) ▫ Decreased transferrin saturation (major iron transport protein) ▫ Increased total iron binding capacity OTHER DIAGNOSTICS ▪ History, physical examination (e.g. colonoscopy for GI bleed) TREATMENT MEDICATIONS ▪ PO iron supplements (e.g. ferrous sulfate) ▪ Parenteral iron ▫ Severe, persistent anemia ▫ Intolerance of PO iron ▫ Nonadherence to PO supplements/ dietary changes OTHER INTERVENTIONS ▪ Increase dietary iron ▫ Heme iron (e.g. meat) absorbed better than non-heme iron (e.g. eggs, legumes, nuts) ▫ Vitamin C increases absorption; calcium decreases absorption ▪ Blood transfusion LEAD POISONING-RELATED ANEMIA osms.it/lead-poisoning PATHOLOGY & CAUSES ▪ Lead exposure, toxicity → anemia ▪ Lead absorbed through lungs/skin/GI tract ▫ Interferes with enzymatic steps in heme pathway → decreased hemoglobin synthesis, microcytosis ▫ Impairs sodium/potassium ATPase in erythrocyte cell membrane → hemolysis RISK FACTORS ▪ Water contaminated with industrial waste/ from pipes made of lead/that contain lead solder ▪ Exposure to leaded paint/paint dust/chips (esp. children); increased risk in older homes (built before 1978, lead in paint since banned) ▪ Exposure to soil/dust contaminated with lead ▪ Breathing industrial emissions containing lead (e.g. smelters, refineries, battery manufacturing, recycling) ▪ Food/ beverages from lead-glazed ceramics SIGNS & SYMPTOMS ▪ Small, hypochromic red blood cells → hypoxemia → decreased oxygen to tissues → tissue hypoxia → fatigue, dyspnea, activity intolerance ▪ Lead toxicity ▫ Abdominal pain, headache, difficulty concentrating, muscle/joint pain, confusion, ataxia OSMOSIS.ORG 417
DIAGNOSIS TREATMENT OTHER INTERVENTIONS LAB RESULTS ▪ ▪ ▪ ▪ ▪ ↑ serum blood lead level (BLL) Basophilic stippling ↓ or normal MCV ↓ mean MCH Hemolysis ▫ ↑ indirect bilirubin, LDH ▫ ↓ haptoglobin ▪ Eliminate exposure ▪ Chelation therapy ▫ Dimercaptosuccinic acid (DMSA, AKA succimer), CaNa2EDTA THALASSEMIA osms.it/thalassemia PATHOLOGY & CAUSES ▪ Thallas = sea; emia = blood ▪ Inherited hemoglobinopathies; most common in individuals with Mediterranean, Middle Eastern, Southeast Asian, African genetic descent ▪ Hemoglobin synthesis with insufficient globin chains → impaired erythropoiesis, malfunctioning erythrocytes ▪ Autosomal recessive inheritance; wide range of phenotypes, clinical syndromes ▪ Deficient alpha/beta chains → imbalanced beta chain to alpha chain ratio → globin chains aggregate, precipitate in erythroid precursors → unstable hemoglobin tetramer ▫ Impaired erythropoiesis ▫ Intramedullary hemolysis and apoptosis ▫ Small, hypochromic cells → decreased oxygen to tissues ▫ Production of few microcytic, hypochromic erythrocytes with rigid, less deformable membranes → extravascular hemolysis, phagocytosis by reticuloendothelial macrophages TYPES Alpha-thalassemia ▪ Deletion of ≥ one gene(s) encoding alpha 418 OSMOSIS.ORG globin chains → absent/ reduced chains ▪ One gene missing: alpha-thalassemia minima ▫ Benign carrier state ▪ Two genes missing: alpha-thalassemia minor, alpha thalassemia trait ▫ Mild anemia ▪ Three genes missing: hemoglobin H (HbH) disease ▫ Mild anemia/may require periodic transfusions (variable presentation) ▪ Four genes missing: alpha-thalassemia major, hydrops fetalis, hemoglobin Barts ▫ Incompatible with extrauterine life due to inability to form normal hemoglobin; death occurs before/shortly after birth ▫ Only hemoglobin Barts (Hb Barts) is produced; tetramers of gamma globulin, oxygen not delivered to fetal tissues ▫ Severe anemia during fetal development → hydrops fetalis → heart failure, hepatomegaly, ascites, death Beta-thalassemia ▪ Genetic mutations of one/both genes → absent/reduced beta chains ▪ Mutation in one beta globin chain: betathalassemia minor, thalassemia trait ▫ Asymptomatic carrier state/mild anemia ▪ Mutation in two beta globin chains: reduced beta globin production → betathalassemia intermedia
Chapter 52 Microcytic Anemias ▫ Heterogeneous presentation ▫ May become transfusion-dependent later in life ▪ No beta globin chains produced: betathalassemia major ▫ Transfusion dependent COMPLICATIONS ▪ Hemolytic, microcytic, hypochromic anemia ▫ Chronic tissue hypoxia ▫ Leg ulcers ▫ High output heart failure ▫ Hypermetabolic state → nutritional deficiencies (children: growth impairment) ▪ Extrameduallary hematopoiesis → bone marrow hyperplasia, bone marrow widens, structural malformations (e.g. facial irregularity, osteoporosis, premature fusion of epiphysis in children) ▪ Hemolysis → increased bilirubin → gallstones ▪ Iron overload, deposition in tissue ▫ Myocardium → arrhythmias, restrictive cardiomyopathy, heart failure ▫ Pancreas, other endocrine glands → endocrinopathies (e.g. diabetes, thyroid dysfunction) ▫ Liver → cirrhosis, hepatocellular cancer ▫ Kidneys → renal insufficiency (metabolic load from high hematopoietic cell turnover) ▪ Hydrops fetalis ▫ Alpha thalassemia major only ▪ Treatment-related complications ▫ Transfusions, chelation therapy SIGNS & SYMPTOMS ▪ With exception of alpha-thalassemia major, mild compared to beta-thalassemia ▪ Decreased oxygen to tissues ▫ Systemic: pallor, fatigue, activity intolerance ▫ Cardiac: altered hemodynamics, e.g. tachycardia, low blood pressure, arrhythmias ▪ Chronic hemolysis ▫ Jaundice, dark urine, hepatosplenomegaly DIAGNOSIS LAB RESULTS ▪ ↓ serum hemoglobin ▪ Decreased/normal/increased reticulocyte count → degree of impaired erythropoiesis ▪ White blood cells, platelets normal ▪ Red blood cell indices ▫ Hypochromic-microcytic erythrocytes ▫ MCHC increased related to erythrocyte dehydration ▫ Decreased MCV ▫ High red cell distribution width (RDW) ▪ Blood smear analysis ▫ Poikilocytosis (dacrocytes, i.e. teardropshaped cells) ▫ Anisocytosis ▫ Erythroblasts (nucleated red blood cells) ▫ Target cells ▫ Inclusions (precipitated globin chains) ▪ Blood chemistry indicative of hemolysis ▫ Increased lactate dehydrogenase (LDH) ▫ Increased indirect (unconjugated) bilirubin ▫ Decreased haptoglobin ▪ Iron studies ▫ Increased serum iron, transferrin saturation (TSAT), serum ferritin ▪ Diagnostics to determine organ involvement (e.g. cardiac MRI, thyroid hormone, glucose levels, bone mineral density) ▪ Hemoglobin analysis using highperformance liquid chromatography (HPLC)/hemoglobin electrophoresis, genetic testing (confirmation) OSMOSIS.ORG 419
TREATMENT ▪ According to phenotype MEDICATIONS ▪ Folic acid supplements: support erythropoiesis SURGERY ▪ Splenectomy OTHER INTERVENTIONS ▪ Blood transfusions ▪ Chelation therapy ▪ Allogeneic hematopoietic cell transplantation (beta-thalassemia major) ▪ Consultation with cardiology, other specialties: organ involvement ▪ Ongoing monitoring: individuals with high impairment (e.g. blood, iron studies; liver studies; growth, development in children) 420 OSMOSIS.ORG

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Microcytic anemia essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Microcytic anemia by visiting the associated Learn Page.