FORMED ELEMENTS• Three types: Erythrocytes – red blood cells Leukocytes – white blood cells Thrombocytes – platelets – cell fragments
Development of hemopoietic system: 3 anatomic stages: Mesoblastic: in extraembryyonic structures - yolk sac (10- 14 days of gestation till 10-12 wks) Hepatic: liver 6-8wks gestation - 20-24wks-primary site of blood cell production (continues till remainder of gestation) Myeloid: bone marrow (10-12 weeks) Exception: lymphocytes –bone marrow+ other organs
Developmental changes:• 2nd to 3rd trimester: circulating erythrocytes and granulocytes increase• 2nd trimester - Haematocrit levels rise 30-40 % & at term rise is 50-63 %• Platelet concentration remains constant from 18th wks till term• Life-span of RBCs ~60- 90 days in newborns vs 120 days
• Fetal bone marrow space develops - 8th wk of gestation• Neutrophils first observed ~ 5 wks of gestation• 14th wk to term: most common cell found in bone marrow is neutrophil• Red marrow:• Newborns- in all cavities of bones• Older children & adults - in upper shaft of femur, humerus, pelvis, spine, skull and bones of thorax• Erythropoiesis: - In-utero controlled by erythroid growth factors produced by monocyte-macrophages of fetal liver - After birth controlled by erythropoietin from kidneys
The Red Cell• Average life span = 120 days (60-90 days NB)• Cleared by RES (spleen, liver primarily)• Homeostasis daily loss = daily production• Otherwise anemia
Hemoglobin:• Is complex protein - Made up of heme which contains an atom of iron and 4 polypeptide globin chains – reversible transport of Oxygen without expenditure of metabolic energy – Oxygen binds to iron in heme (also CO) – 23 % of CO2 is bound to globin portion• If there is a problem with any part of the molecule it may not be functional
Developmental changes in Hb:• 4-8 wks gestation: Gower Hb predominates; disappears by 3rd month• > 8th wk of gestation- Hb F predominant Hb• ~ 24 wks gestation 90 % of total Hb• At birth declines to 70 %• 6-12 months postnatal life < 2 %
Developmental changes in Hb:• 16-20 wks gestation- some Hb A detectable• 24th wk gestation: 5-10 % , At term ~ 30 %Hb A present• Hb A2 - < 1 % - At birth - 2-3.4 % At 12 months (normal level)• Throughout life ratio of Hb A: Hb A2 is ~ 30:1
Hgb Norms• Normal values vary by age and gender – High at Birth 20g/dl since HbF has high affinity for oxygen , by 3 months HbA replaces HbF – Falls to lower-than-adult values by 3-6 months – Rises gradually to adult value by the early teenage years – On average, Adult male Hb 2g/dl > female counterpart due to effect of androgen .
Hgb and MCV Variability Age Hgb mean MCV mean birth 16.5 108 2 wk 16.5 105 2 mo 11.5 96 6mo-2yr 12.5 77 2-6 yr 12.7 80 10-12 yr 13.5 85 12-17 14 85 Adult 14-16 90Contemporary Pediatrics, Vol 18, No. 9
GRANULOCYTES• Neutrophils – phagocytes• Eosinophils – red granules, associated with allergic response and parasitic worms• Basophils – deep blue granules - Release heparin and histamine
Lab Investigation• Table: Laboratory Tests in Anemia Diagnosis• i. Complete blood count (CBC)• A. Red blood cell count• 1. Hemoglobin• 2. Hematocrit• B. Red blood cell indices• 1. Mean cell volume (MCV)• 2. Mean cell hemoglobin (MCH)• 3. Mean cell hemoglobin concentration (MCHC]• 4. Red cell distribution width (RDW)C.
RBC indices• Part of the (CBC) -• Mean cell volume(MCV) – Quantifies average red blood cell size• Mean cell hemoglobin (MCH) –Hb amount per red blood cell• Mean cell hemoglobin concentration (MCHC) - The amount of hemoglobin relative to the size of the cell (hemoglobin concentration) per red blood cell
Anemias - based on cell size (MCV) and amount of Hgb (MCH)• MCV < lower limit of normal: microcytic anemia• MCV normal range: normocytic anemia• MCV > upper limit of normal: macrocytic anemia• MCH < lower limit of normal: hypochromic anemia• MCH within normal range: normochromic anemia
Mentzer index• Calculated number to help differentiate between iron deficiency vs. thalassemia if having microcytic anemia• MCV/RBC• >13 iron deficiency• <13 thal trait
Red Cell Volume Distribution Width (RDW)• Reflects the variability in cell size• Aids in further differentiating between specific etiologies of microcytic, normocytic, and macrocytic• RDW = (Standard deviation of MCV ÷ mean MCV) ×
Contd• C. White blood cell count• 1. Cell differential• 2. Nuclear segmentation of neutrophils• D. Platelet count
Blood smear• Assess the size, color, and shape of red cells– Look for abnormalities – macrocyte, leptocyte, target cell, Tear drop, Elliptocytosis,burr cell,acanthocyte, Schistocytes,Spherocytosis,Sickle cells,Poikilocytes – Anisocytosis, Polychromasia
Microcytic and Hypochromic Smaller than normal ( <7 µm diameter Less hemoglobin in cell. Enlarged area of central pallor.
Elongated cell with pointed ends.Sickle cell Hemoglobin S and certain types of hemoglobin CSpherocyte Loss of central pallor, stains more densely, often microcytic. Hereditary spherocytosis and certain acquired hemolytic anemias.poikilocytosis & variation in shape and variation in size anisocytosis
Contd• II. Reticulocyte count• III. Iron supply studies• A. Serum iron• B. Total iron-binding capacity• C. Serum ferritin, marrow iron stain
Contd• IV. Marrow examination• A. Aspirate• 1. E/G ratio• 2. Cell morphology• 3. Iron stain• B. Biopsy• 1. Cellularity• 2. Morphology E/G ratio, ratio of erythroid to granulocytic precursors.
Reticulocyte Count• Reticulocyte production index• RPI= Retic ct x Hb(obsv)/ Hb(normal) x0.5• Indicates whether the BM is appropriately responding to anemia• RPI >3 : inc prod = blood loss/hemolysis• RPI <2 : dec prod / ineffective prod
What is Anemia?• Anemia is defined as a reduction of the red blood cell (RBC) volume or hemoglobin concentration below reference level for the age and sex of the individual• Hb < - 2SD or 95th centile for age and sex
Anemia BasicsAll anemias are either due to….1. Ineffective RBC production or2. Accelerated destruction of the RBC
Classification• By RBC morphology and By Etiological factors responsible for anemia
Normocytic, Normochromic anemia1. Impaired cell production (low reticulocyte count) - aplastic anemia - pure red cell aplasia - physiological anemia of infancy - infections - Systemic diseases like endocrinal, renal and hepatic diseases - bone marrow replacement – leukemia, tumors, starage ds, myelofibrosis, osteopetrosis2 Hemolytic anemia ( reticulocyte count high)
DIMORPHIC ANEMIA• When two causes of anemia act simultaneously, e.g : macrocytic hypochromic due to hookworm infestation leading to deficiency of both iron and vitamin B12 or folic acid• following a blood transfusion
ETIOLOGICAL CLASSIFICATION OF ANEMIA• Blood loss Acute Chronic• Decreased iron assimilation - Nutritional deficiency - Hypoplastic or aplastic anemia - Bone marrow infiltration like leukemia & other malignancies, - Myelodysplastic syndrome - Dyserythropoietic anemia
ETIOLOGICAL CLASSIFICATION OF ANEMIA• Increased physiologic requirement- Extracorpscular - alloimmune & isoimmune hemolytic anemia, microangiopathic anemias, infections, hypersplenism, - Intracorpsular defect – Red cell membranopathy i.e. congenital spherocytosis, elliptocytosis – Hemoglobinopathy like HbS, C,D,E etc. Thalassemia syndrome – RBC enzymopathies like G6PD deficiency, PK deficiency etc.
Differential of Anemia Hgb, indices, retic count and smear Inadequate response (RPI<2) Adequate response (RPI>3) r/o blood loss/hemolytic disHypochromic, microcytic Normochromic,normocytic Macrocytic hemoglobinopathy iron def chronic dis B12/folate def enzymopathy thalssemia Ca/BM failure Liver disease membranopathy chronic disease Transient erythroblastopenia Down Syndrome extrinsic factors of childhood (DIC,HUS,TTP) lead poisoning Renal disease Drugs (etoh) Immune Hemolytic anemia
Follow-up• Re-check CBC 4-6 weeks (to confirm response)• Continue iron 3-4 months (to replace stores)• Generally, should not need treatment for more than 5 months unless there are ongoing losses• If no improvement on adequate iron therapy, consider evaluating the child for lead poisoning or thalassemia
PHYSIOLOGIC ADJUSTMENTS• increased cardiac output• increased oxygen extraction (increased arteriovenous oxygen difference)• shunting of blood flow toward vital organs and tissues• the concentration of 2,3-diphosphoglycerate (2,3-DPG) increases within the RBC• The resultant “shift to the right” of the oxygen dissociation curve, reducing the affinity of hemoglobin for oxygen, results in more complete transfer of oxygen to the tissues
CLINICAL FATURES• weakness• tachypnea• shortness of breath on exertion• tachycardia• cardiac dilatation• congestive heart failure• ultimately result from increasingly severe anemia, regardless of its cause.
D/D of microcytic anemia: TIBC BM Iron Comment Serum IronIron deficiency D I 0 Responsive to iron therapy Chronic D D ++ Unresponsive to iron inflammation therapy Thalassemia I N ++++ Reticulocytosis and major indirect bilirubinemia
Serum iron TIBC BM Comment Iron Elevation of A of fetalThalassemia minor N N ++ hemoglobin, target cells, and poikilocytosisLead poisoning N N ++ Basophilic stippling of RBCsSideroblastic I N ++++ Ring sideroblasts in marrow
PYROPOIKILOCYTE • RBCs w/c are extremely sensitive to heat