hematopoeisis Bone marow examination Normal bone marrow 1
hematopoeisis
Bone marow examination Normal bone marrow 1. Haemopoietic cells. Morphology of haemopoietic cells l Granulocytes & their precursors – 60% l Erythroid precursors – 20 % l Lymphocytes & Monocytes & their precursors – 10% l Unidentified or disintegrating cells – 10% 2. Myeloid : erythroid ratio – 3 -4 : 1
Anaemia l Anaemia may be defined as a state in which the blood Hg is below the normal range fro the age & sex of the patient Normal count/Range Hemoglobin l Male – 13 – 18 gm/dl l Female -11. 5 – 16. 5 gm/dl Red cell count – l Male - 4. 5– 6. 5 million/cu mm of blood l Female – 3. 8– 4. 8 l Reticulocyte count - 0. 2– 2. 0% Hemoglobin (Hb) Red cell count Reticulocyte count g/d. L 13. 6 -17. 2 12. 0 -15. 0 × 106/mm 3 % 4. 3 -5. 9 0. 5 -1. 5 3. 5 -5. 0 0. 5 -1. 5
Factors necessary for Erythropoiesis. A] General Factors l 1] Diet-Protein is essential for synthesis of Globin in of Haemoglobin l Iron-essential for heam production l Others-Cu, Mg, Cobalt, Ca etc. l 2] Hypoxia-hypoxia causes Liberation of hormone Erythropoietin which stimulate bone marrow for Erythropoiesis l 3] Erythropoietin l 4] Endocrine gland- Adrenal Gland, Pituitary Gland, Thyroid Gland. B] Maturation factors l 1] Vit. B 12 l 2] Folic Acid l 3] Intrinsic Factor of Castle-It helps in absorption of Vit. B 12 from gut and thus indirectly help in maturation.
Classification of Anemia Morphological & Aetiological Classification Morphological classification Based mainly on MCV & MCHC. MCH may be included 1. Microcytic Hypochromic aneamia MCV, MCHC & MCH are below normal E. g. – IDA, thalassaemia, anaemia of chronic diseases
2. Macrocytic anaemia l MCV is above normal. MCHC is normal l E. g. megaloblastic anaemia 3. Normocytic Normochromic anaemia l MCV, MCHC MCH are within normal range l E. g. acute blood loss, haemolytic anemia l
Aetiological Classification This classification is based on pathophysiology & cause Impaired RBC production Hemolytic anemia Blood Loss
Impaired RBC production A. Deficiency of essential nutrients (Deficiency anaemia) Iron deficiency – most common cause Vitamin B 12 deficiency Folic acid deficiency Combined deficiency Others – protein calorie malnutrition , vitamin C deficiency l
B. Depression of erythropoiesis Anemia of chronic disease – Chronic renal failure. Liver diseases, Malignancy Invasion of bone marrow – leukaemia , secondary carcinoma Aplastic anemia
B. Haemolytic anemia l Intracorpuscular defect l Extracorpuscular defect C. Blood Loss l Acute Blood loss – loss of large volume of blood over a short period l Chronic blood loss e. g hookworm infestation, bleeding peptic ulcer, piles, menorrhagia
Clinical features of anemia l Tiredness , Fatigue l Lethargy l Palpitaion l Pallor is the most important physical sign
Laboratory diagnosis of anemia l Hb estimation l Diagnosis of Morphological type of anaemia l Diagnosis of aetiological type of anemia – discussed under individual type of anemia
Packed cell volume (PCV) l Is the volume of red cells in relation to that of whole blood PCV = MCV X red cell count Normal values l 40 – 45 % male l 37 - 47 % female MCV (Mean corpuscular volumes ) l Indicates the average volume red cells l Normal 76 - 96 fl (femolitre)
MCH (mean corpuscular hemoglobin ) l Indicates average weight of Hb contained in each cell l Does not take into count cell size l Obtained by dividing Hb by red cell /liter & multiplied by 10 13 If Hb 15 g/dl Red cell – 5 X 1012/L MCH = 15 X 1013 / 5 X 1012 = 30 pg l Normal 27 -32 pg l
MCHC (mean corpuscular haemoglobin concentration) l Indicates the average concentration of Hb within average red cells l Usually 3 times higher that the whole blood Hb conc. l Obtained by dividing Hb by PCV /liter If Hb 15 g/dl PCV – 0. 45 l/l MCHC = 15/0. 45 = 33. 3 g/dl l Normal – 31 -35 g/dl l
Diagnosis of morphological type of anemia 1. Examination of peripheral blood film 2. Determination of Red cell absolute value l MCV & MCHC are below normal values – microcytic hypochromic anemia l MCV is above normal & MCHC is normal – macrocytic anemia l MCV & MCHC are normal – normocytic normochromic aneamia
Iron deficiency anemia Most common type of anemia Total body iron content l Male – upto 6 gm l Female – 2 gm 80% of functional body iron is found in hemoglobin, rest found in myoglobin and iron-containing enzymes (e. g. catalase & cytochromes). The iron storage pool, represented by hemosiderin and ferritin-bound iron (15% to 20% of total body iron. ) l Stored iron is found mainly in the liver, spleen, bone marrow, and skeletal muscle. Male Fem
Absorption l Most absorbed in Duodenum
Causes /pathogenesi of iron deficiency 1. Inadequate iron intake l Nutritional deficiency – deficient diet 2. Impaired absorbtion – coeliac disease, tropical sprue, gastrectomy or gastro-enterostomy
Causes /pathogenesi of iron deficiency 3. Increased physiological demand l During period of growth in children l During reproductive life in female – menstruation, pregnancy, parturation & lactation increase the physiological requirement fro iron 4. Chronic blood loss – the gastrointestinal tract (e. g. , peptic ulcers, colonic cancer, hemorrhoids, hookworm disease) or the female genital tract (e. g. , menorrhagia, cancers)
Laboratory diagnosis of IDA Investigation & findings 1. Blood Picture l Hb – Variably reduced l Blood film – hypochromic, microcytic, anisocytosis. Poikilocytosis in severe cases target, elliptical, oval & pencil cells l Haematocrit – reduced l MCV – reduced(microcytosis) MCHC – reduced (hypochromic) & MCH is reduced
2. biochemical findings (confirm IDA) l Serum iron - reduced l Serum ferritin - reduced l Total iron binding capacity – increased l Percentage saturation of iron binding protein – decreased 3. Bone marrow l Although erythropoietin levels are increased, the marrow response is blunted by the iron deficiency, and thus the marrow cellularity is usually only slightly increased Diagnostic criteria include l Anemia, hypochromic and microcytic red cell indices, low serum ferritin and serum iron levels, low transferrin saturation, increased total iron-binding capacity, and, ultimately, response to iron therapy
4. Further Investigation l Stool examination for l Ova of hookworm & l Occult blood l Urine examination for haematuria l Other investigations depending on clinical findings
Megaloblastic aneamia l MA are characterized by formation of morphologically abnormal (enlarged) nucleated red cell precursors called megaloblasts in the bone marrow. l The change occurs due to deficiency of vitamin B 12 or folate
Vitamin B 12 l Abundant in all animal foods, including eggs and dairy products, and is resistant to cooking and boiling. l Even bacterial contamination of water and non animal foods can provide adequate amounts. l It is stored in the liver, which normally contains reserves that are sufficient to support bodily needs for 5 to 20 years l As a result, deficiencies due to diet are rare and are virtually confined to strict vegans
Metabolism of vitamin B 12 l Peptic digestion release dietary vitamin B 12, l Binds to salivary B 12 -binding proteins called R binders. l l l R-B 12 complexes transported to duodenum Processed by pancreatic proteases to releases B 12, Attaches to intrinsic factor (gastric juice) The intrinsic factor-B 12 complex passes to the distal ileum Attaches to the epithelial intrinsic factor receptors - absorption of vitamin B 12 bound to transport proteins called transcobalamins, which then deliver it to the liver and other cells of the body.
Causes of Megaloblastic Anemia Vitamin B 12 Deficiency l Decreased intake Inadequate diet, vegetarianism Impaired absorption Intrinsic factor deficiency - Pernicious anemia, Gastrectomy Malabsorption states Diffuse intestinal disease e. g. lymphoma Ileal resection, ileitis Competitive parasitic uptake - Fish tapeworm infestation Bacterial overgrowth in blind loops and diverticula of bowel Increased requirement Pregnancy, hyperthyroidism, disseminated cancer
Folate metabolism l Best sources - fresh uncooked vegetables and fruits. l The principal site of intestinal absorption is the upper third of the small intestine l Conversion from dihydrofolate to tetrahydrofolate by the enzyme dihydrofolate reductase is particularly important. l Tetrahydrofolate involved in the synthesis of purines and thymidylate, the building blocks of DNA,
Megaloblastic anemia Folic Acid Deficiency Decreased intake Inadequate diet—alcoholism, infancy Impaired absorption Malabsorption states Intrinsic intestinal disease Increased metabolism Anticonvulsants, oral contraceptives Increased loss Hemodialysis Increased requirement Pregnancy, infancy, disseminated cancer, markedly increased hematopoiesis Impaired use Folic acid antagonists – e. g. Methotrxate
Pathogenesis of Megaloblastic anemia l Deficiency of Vit B 12/folic acid l Impairment of DNA synthesis, l Results in a delay in nuclear maturation and cell division. l Synthesis of RNA and cytoplasmic elements proceeds at a normal rate l Hematopoietic precursors show nuclear-cytoplasmic asynchrony l Undergo apoptosis in the marrow (ineffective hematopoiesis)
Laboratory diagnosis of MA Blood l Hb– reduced l Blood film l RBC- many oval macrocytes, Anisocytosis, poikilocytosis, Polychromatic & stippled cells, howell-jolly bodies l White cells – hypersegmented neutrophils are always present (49 lobes) Megaloblastic blood compared to normal blood hypersegmented neutrophil with a six-lobed nucleus
l l l Haematocrit (PCV)– reduced Red cell count – reduced MCV is high, MCHC is normal WBC – leucopenia (neutropenia) Platelets – thrombocytopenia Reticulocyte count – increased 2. Biochemical findings l Serum iron & ferritin – increased l Serum bilirubin – may be slightly increased in Vit B 12 deficiency l Lactate dehydrogenase – increased Male Fem
3. Bone marrow l Cellularity – Hypercellular (increased numbers of megaloblasts) l M: E ratio is reduced or even reversed l Erythropoiesis - Megaloblastic erythropoiesis l Granulopoiesis is active – giant metamyelocyte with u shaped nucleus l Iron in large amount. Sideroblast – increased A to C, Megaloblasts-various stages of differentiation
4. Special tests for vitamin B 12 deficiency l Serum vitamin B 12 assay l Schilling test – detects ability of the body to absorb vit B 12 after correction. Radioactive cobalt labeled vit B 12 is used for the test. A small oral dose is given. Radioactivity in the urine is measured l Methylmelonic acid excretion in urine - increased l Therapeutic trail - Response to vit B 12 administration
5. Special Tests for folate deficiency l Serum folate assay l Red cell folate assay l Theurapeutic trail - Response to folic acid administration
Pernicious anemia PA is a vitamin B 12 deficiency megaloblastic anaemia Pathogenesis l PA occurs due to failure of secretion of Intrinsic factor by the stomach due to permanent gastric atrophy l Vit B 12 in food not absorbed (gastrectomy, resection of ileum ) Special tests l Pentagastrin fast achlohydria l Anti-intrinsic factor & anti-parietal cell antibodies in serum
l Diagnosis is made by l (1) low serum vitamin B 12 levels, l (2) normal or elevated serum folate levels, l (3) serum antibodies to intrinsic factor, l (4) moderate to severe megaloblastic anemia, l (5) leukopenia with hypersegmented granulocytes, and l (6) a dramatic reticulocytic response (within 2 -3 days) to parenteral administration of vitamin B 12.
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