Microcytic anemia Notes

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