Hematology lecture 1 (2).pptx

hematology The diagnosis of anemia in men is based on a hemoglobin of less than 130 to 140 g/L (13 to 14 g/dL); in women, it is less than 120 to 130 g/L (12 to 13 g/dL) Iron deficiency anemia • Iron deficiency is the commonest cause of anemia worldwide and is frequently seen in general practice....

hematology The diagnosis of anemia in men is based on a hemoglobin of less than 130 to 140 g/L (13 to 14 g/dL); in women, it is less than 120 to 130 g/L (12 to 13 g/dL) Iron deficiency anemia • Iron deficiency is the commonest cause of anemia worldwide and is frequently seen in general practice. • The anaemia of iron deficiency is caused by defective synthesis of haemoglobin, resulting in red cells that are smaller than normal (microcytic) and contain reduced amounts of haemoglobin (hypochromic). Iron metabolism • Iron has a pivotal role in many metabolic processes, and the average adult contains 3-5 g of iron, of which two thirds is in the oxygen-carrying molecule haemoglobin. • A normal Western diet provides about 15 mg of iron daily, of which 5-10% is absorbed (1 mg), • principally in the duodenum and upper jejunum, where the acidic conditions help the absorption of iron in the ferrous form. Absorption is helped by the presence of other reducing substances, such as hydrochloric acid and ascorbic acid. • Once absorbed from the bowel, iron is transported across the mucosal cell to the blood, where it is carried by the protein transferrin to developing red cells in the bone marrow. • Iron stores comprise ferritin, a labile and readily accessible source of iron, and haemosiderin, an insoluble form found predominantly in macrophages Clinical features of iron deficiency • The symptoms accompanying iron deficiency depend on how rapidly the anemia develops. • In cases of chronic, slow blood loss, the body adapts to the increasing anaemia, and patients can often tolerate extremely low concentrations of hemoglobin • Tachycardia and cardiac failure may occur with severe anemia irrespective of cause, On examination, several skin, nail, and other epithelial changes may be seen in chronic iron deficiency. nail changes such as koilonychia (spoon shaped nails) may result in brittle, flattened nails. angular stomatitis, in which painful cracks appear at the angle of the mouth, sometimes accompanied by glossitis. Management • Oral iron replacement therapy Oral ferrous salts are the treatment of choice (ferric salts are less well absorbed) 200 mg three times daily • Alternative preparations include ferrous gluconate and ferrous fumarate. Failure to respond to oral iron Therapy • The main reason for failure to respond to oral iron therapy is poor compliance.??????? • if the losses ( bleeding) exceed the amount of iron absorbed daily, the haemoglobin concentration will not rise as expected • The presence of underlying inflammation or malignancy may also lead to a poor response to therapy. • incorrect diagnosis of iron deficiency anemia should be considered in patients who fail to respond adequately to iron replacement therapy. Parenteral iron may be used when • the patient cannot tolerate oral supplements—for example, when patients have severe gastrointestinal side effects or • if the losses exceed the daily amount that can be absorbed orally. Macrocytic anaemias Macrocytosis is a rise in the mean cell volume of the red cells above the normal range . The causes of macrocytosis fall into two groups: (a)deficiency of vitamin B12 (cobalamin) or folate (or rarely abnormalities of their metabolism) in which the bone marrow is megaloblastic, (b) other causes, in which the bone marrow is usually normoblastic. vitamin B12 deficiency is usually due to pernicious anaemia, which now accounts for up to 80% of all cases of megaloblastic anaemia. The underlying mechanism is an autoimmune gastritisThat results in achlorhydria and the absence of intrinsic factor Consequences of vitamin B12 or folate deficiencies • Clinical features include pallor and jaundice. • In severe cases, the white cell count and platelet count Also fall (pancytopenia). • The bone marrow shows characteristic megaloblastic erythroblasts and giant metamyelocytes (granulocyte precursors). • A minority of patients with vitamin B12 deficiency develop a neuropathy due to symmetrical damage to the peripheral nerves and posterior and lateral columns of the spinal cord, the legs being more affected than the arms. • Psychiatric abnormalities and visual disturbance may also occur. • Glossitis Treatment • Vitamin B12 deficiency is treated initially by giving the patient six injections of hydroxo-cobalamin 1 mg at intervals of about three to four days, followed by four such injections a year for life. • For patients undergoing total gastrectomy or ileal resection it is sensible to start the maintenance injections from the time of operation. • Folate deficiency is treated with folic acid, usually 5 mg daily orally for four months, which is continued only if the underlying cause cannot be corrected. Vitamin B12 deficiency must be excluded in all patients starting folic acid treatment at these doses as such treatment may correct the anaemia in vitamin B12 deficiency but allow neurological disease to develop. Hemolytic Anemias • Hemolysis is the accelerated destruction, and hence decreased life span, of red blood cells (RBCs). • Clinically, hemolytic anemia produces variable degrees of fatigue, pallor, and jaundice, Splenomegaly occurs in some conditions The complete blood count shows anemia and reticulocytosis that depend • on the severity of hemolysis and • the degree of bone marrow compensation Inheritance Inherited eg Sickle cell anemia Acquired eg Autoimmune hemolytic anemia Site of RBC Destruction Intravascular eg Paroxysmal nocturnal hemoglobinuria Extravascular eg Hereditary spherocytosis Origin of RBC Damage Intrinsic eg Pyruvate kinase deficiency Extrinsic eg Thrombotic thrombocytopenic purpura Thalassemias Management of the β-thalassemias • RBC transfusion. • Iron chelation therapy • Splenectomy is performed to alleviate abdominal symptoms or increased transfusion requirements but usually is delayed until after the age of 5 years. • Allogeneic bone marrow transplantation THANKS