ANEMIA And Its Laboratory Diagnosis By: Ahmad Sh. Silmi IUG, Hematologist firstname.lastname@example.org
Objectives At the end of this chapter you will be able to: • Define anemia • Discuss the causes and clinical significance of different categories of anemia • Describe the classification of anemia • Explain - Microcytic anemia - Macrocytic anemia - Normochromic normocytic anemia • Discuss the laboratory findings for each category of anemia • Perform basic laboratory tests for the diagnosis of anemia
Chapter Outline 3.1. Definition of anemias 3.2. Classification of anemias 3.2.1. Hematologic Response to Anemia 3.2.2. Signs of Accelerated Bone Marrow Erythropoiesis 3.2.3. Physiologic Response to Anemia 3.2.4. Methods of classification 3.2.5. Anemia Diagnosis/Cause 3.2.6. Lab Investigation of Anemia 3.3. Types of anemia . 3.3.1 microcytic hypochromic anemia 3.3.2. macrocytic normocytic anemias 3.3.3. normocytic anemias 3.3.4. normocytic anemias due to hemoglobinopathies
3.1. Introduction 3.1.1. Definition of Anemia Anemia is a decrease in the RBC count, Hgb and/or HCT values as compared to normal reference range for age and sex (Also determined by alteration in plasma volume) ‘True’ anemia: decreased RBC mass and normal plasma volume Pseudo or dilutional anemia: normal RBC mass and increased plasma volume An increase in plasma volume can occur in Pregnancy, volume overload (IVs) congestive heart failure Low Hgb and HCT values
3.1.1. Definition of Anemia cont’d….. • Anemia must also relate to the level of hemoglobin the individual normally possesses. • If an adult male usually maintains a hemoglobin level of 16g/dl, and over a period of days is noted to have decreased to 14g/dl, this must be considered significant even though both values are within the normal range for an adult male.
3.1.1. Definition of Anemia cont’d….. • Various diseases and disorders are associated with decreased hemoglobin levels. These include: • Nutritional deficiencies • External or internal blood loss • Increased destruction of RBCs • Ineffective or decreased production of RBCs • Abnormal hemoglobin synthesis • Bone marrow suppression by toxins, chemicals, or radiation & replacement by malignant cells • Infection
3.1.1. Definition of Anemia cont’d….. • Functionally anemia is defined as tissue hypoxia (inability of the body to supply tissue with adequate oxygen for proper metabolic function) • There is an abnormal hemoglobin with an increased O2 affinity resulting in an anemia with normal or raised hemoglobin levels, hematocrit, or RBC count. • Generally anemia is not a disease, but rather the expression of an underlying disorder or disease.
3.1.1. Definition of Anemia cont’d….. • Anemia may develop: • When RBC loss or destruction exceeds the maximal capacity of bone marrow RBC production or • When bone marrow production is impaired
3.1.2.Hematologic Response to Anemia Tissue hypoxia causes increased renal release of erythropoietin (EPO) to accelerate bone marrow erythropoiesis The normal bone marrow can increase its activity 7-8 times normal Marrow becomes hypercellular
Signs of Accelerated Bone Marrow Erythropoiesis • The marrow becomes hypercellular due to a marked increase in RBC precursors (called erythroid hyperplasia) and the M:E ratio falls. • Nucleated RBCs may be released into the blood circulation along with the outpouring of reticulocytes • NRBC number tends to correlate with the severity of anemia • Increased polychromasia on the Wright's- stained blood smear is seen due to increased number of circulating Retics.
If demand exceeds maximal bone marrow activity, RBC production may occur in extramedullary sites, liver, spleen (hepatosplenomegaly).
3.1.3. Physiologic Response to Anemia Ability to adapt to anemia depends on: Age and underlying disease Cardio/pulmonary function Rate at which anemia develops (BM can compensate easier if the onset of anemia is slow), Underlying disease
3.1.4. Clinical features: • Symptomsof hypoxia: decreased oxygen delivery to the tissues/organs causes: • fatigue , faintness, weakness, dizziness, headaches, dyspnea, poor exercise tolerance, leg cramps.
3.1.4.Clinical features cont’d….: Signs of anemia • general signs include pallor of mucous membrane, which occur if the Hgb concentration is less than 9g/dl, • specific signs are associated with particular types of anemia, for example, jaundice in hemolytic anemia, leg ulcer in sickle cell anemia
3.1.5. Diagnosis of anemia • Before making a diagnosis of anemia, one must consider: • Age • Sex • Geographic location
3.1.5. Diagnosis of anemia cont’d…… • How does one make a clinical diagnosis of anemia? A. Patient history • Dietary habits • Medication • Possible exposure to chemicals and/or toxins • Description and duration of symptoms
3.1.5. Diagnosis of anemia cont’d…… Patient history cont……….. • Tiredness • Muscle fatigue and weakness • Headache and vertigo (dizziness) • Dyspnia (difficult or labored breathing) from exertion • G I problems • Overt signs of blood loss such as hematuria (blood in urine) or black stools
3.1.5. Diagnosis of anemia cont’d…. B. Physical exam • General findings • Hepato or splenomegaly • Heart abnormalities • Skin pallor • Specific findings • In vitamin B12 deficiency there may be signs of malnutrition and neurological changes • In iron deficiency there may be severe pallor, a smooth tongue, and esophageal webs • In hemolytic anemias there may be jaundice due to the increased levels of bilirubin from increased RBC destruction
3.1.5. Diagnosis of anemia cont’d…… C. Lab investigations • A complete blood count, CBC • RBC count • Hematocrit (Hct) or packed cell volume • Hemoglobin determination • RBC indices calculation • Reticulocyte count • Blood smear examination to evaluate: • Poikilocytosis • Leukocytes or Platelets abnormalities
3.1.5. Diagnosis of anemia cont’d….. Lab investigation cont’d…… • A bone marrow smear and biopsy to observe: • Maturation of RBC and WBC series • Ratio of myeloid to erythroid series • Abundance of iron stores (ringed sideroblasts) • Presence or absence of granulomas or tumor cells • Red to yellow ratio • Presence of megakaryocytes
3.1.5.Diagnosis of anemia cont’d….. 4. Hemoglobin electrophoresis
3.1.5. Diagnosis of anemia cont’d….. Lab investigation cont’d…… 5. Antiglobulin testing 6. Osmotic fragility test
3.2. Methods of Anemia Classification Several schemes of classifying anemias exist Morphologic Based on RBC morphology Anemia is divided into three groups mainly on the basis of the MCV (RBC indices) Pathophysiologic Anemia is divided using three main causes/mechanisms Impaired erythrocyte formation (Aplastic anemia, IDA, sideroblastic anemia, anemia of chronic diseases, megaloblastic anemia) Retic count is low The bone marrow fails to respond appropriately due to disease or lack of essential supplies
Methods of Classification cont’d Increased blood loss (Acute, Chronic) Retic count is typically high Anemia results when red cell loss exceeds the bone marrow’s capacity to increase its activity Increased destruction of RBCs (hemolytic anemias) Retic count is typically high Anemia results when red cell destruction exceeds the bone marrow’s capacity to increase its activity
Methods of Classification cont’d Morphologic Categories of Anemia • Normocytic Normochromic anemia (normal red cell indices) • Blood loss anemia • Hemolytic anemia • Aplastic anemia • Chronic diseaes • Renal insufficciency
Methods of Classification cont’d Morphologic Categories of Anemia • Microcytic hypochromic ( low red cell indices) • Iron deficiency anemia • Sideroblastic anemia • Lead poisoning • Thallassemia • Chronic diseases
Methods of Classification cont’d Morphologic Categories of Anemia • Macrocytic Normochromic ( high MCV and MCH, normal MCHC) • Megaloblastic anemia • Liver disease • Post splenectomy • Hypothyroidism • Stress erythropoiesis
Morphologic Categories of Anemia 1 Microcytic/hypochromic 2 2 Macrocytic/Normochromic 1 N.B. The nucleus of a small lymphocyte (shown by the arrow) is used as a reference to a normal red cell size 3 3 Normocytic/Normochromic
3.2.2. Pathophysiological classification 1. A. B. 2.
Microcytic- Hypochromic Anemia • Many RBCs smaller than nucleus of normal lymphocytes • Increased central pallor. • Includes • Iron deficiency anemia • Thalassemia • Anemia of chronic disease • Sideroblastic anemia • Lead poisoning
The Cause of Microcytic-Hypochromic Anemia Iron Protoporphyrin • Iron deficiency • Chronic inflammation or malignant (ACD) • Sideroblastic anemia Heme Globin + • Thalassemia( or ) Hemoglobin
Microcytic/Hypochromic Anemias Normoblastic RBC maturation normocytic red cells RBC maturation in microcytic anemias Normal RBC maturation is shown for comparison Abbott Manual
A. Iron Deficiency Anemia (IDA) Is a condition in which the total body iron content is decreased below a normal level This results in a reduced red blood cell and hemoglobin production More than half of all anemias are due to iron deficiency.
Iron Deficiency Anemia (IDA) • Causes: • Nutritional deficiency • Malabsorption (insufficient or defective absorption) • Inefficient transport, storage or utilization of iron • Increased need • Chronic blood loss (GI bleeding, ulcer, heavy menstruation, etc)
DIETARY SOURCES OF IRON Organic iron eg beef Inorganic Iron eg lentils DAILY IRON REQUIREMENT 10-15mg/day (5-10% absorbed)
Estimated daily iron requirements Units are mg/day Adult men 0.5-1 Postmenopausal female 0.5-1 Menstruating female 1-2 Pregnant female 1.5-3 Children 1.1 Female (age 12-15) 1.6-2.6
Iron absorption, Transport and storage Iron absorbed from duodenum and jejunum in the GIT Moves via circulation to the bone marrow Incorporated with protoporpyirin in mitochondria of the erythroid precursor to make Heme
There are three proteins important for transporting and storage of iron: • Transferrin, • Transferrin receptors and • Ferritin Transport: • Transferrin: transports iron from the plasma to the erythroblasts in the marrow for erythropoiesis • The transferrin will bind to transferrin receptor on the erythrocyte membrane
Storage • Hgb contains about two third of the body iron • At the end of their life, RBCs are broken down in the macrophage of reticuloendothelial system and then iron is released from Hgb enters plasma and provided to transferrin. • Some stored in reticuloendothelial cell as ferritin soluble protein – iron complex) and hemosiderin (37%) (degraded form of ferritin insoluble) • iron is also found in muscles as myoglobin and in other cells as iron containing enzymes
The distribution of body iron Amount of iron Male Female % in average adult (g) (g) of total Hb 2.41.765 ferritin & hemosiderin 1.00.330 Myoglobin 0.150.123.5 Heme enzyme 0.020.150.5 Transferrin-bound 0.0040.0030.1 iron
Iron Deficiency Anemia (IDA) Sequence of iron depletion When iron loss or use exceeds absorption, there is a sequence of iron depletion in the body: • Storage iron decreases/ low serum ferritin; serum iron & TIBC are normal, no anemia, normal red cells. • Serum iron decreases/TIBC increases (increased transferrin); no anemia, normal red cells. • Anemia with microcytic/hypochromic red cells = IDA.
CLINICAL FEATURES IRON DEFICIENCY Symptoms eg. fatigue, dizziness, headache Signs eg. pallor, Tongue atrophy/ glossitis - raw and sore, angular cheilosis (Stomatitis) Angular Cheilosis or Stomatitis Koilonychia Glossitis
Clinical signs and symptoms Spoon‑shaped nails (koilonychia), brittle nails and hair.
Lab Investigation of IDA Iron tests ►Used to differentiate microcytic hypochromic anemia's or detect iron overload (hemochromatosis) Iron circulates bound to the transport protein transferrin Transferrin is normally ~33% saturated with iron Iron tests include serum iron, Total Iron Binding Capacity (TIBC), serum ferritin
Lab Investigation cont’d Serum iron level measures the amount of iron bound to transferrin Does not include the free form of iron Total Iron Binding Capacity (TIBC) Is an indirect measure of the amount of transferrin protein in the serum Inversely proportional to the serum iron level If serum iron is decreased, total iron binding capacity of transferrin increased (transferrin has more empty space to carry iron)
Lab Investigation cont’d Serum ferritin indirectly reflects storage iron in tissues found in trace amount in plasma It is in equilibrium with the body stores Variation in the quantity of iron in the storing compartment is reflected by plasma ferritin concentration e.g. Plasma ferritin is decreases in IDA Plasma ferritin increases in ACD Limitation: During infection or inflammation Serum Ferritin increases like other acute phase proteins, and then it is not an accurate indicator in such situations.
Bone marrow iron (Tissue iron) Tissue biopsy of bone marrow Prussian blue stain Type of iron is hemosiderin