Anemia

Anaemia

Dr. Sura Obay Al-Dewachi M.Sc Pathology/ Hematology

Objectives

At the end of this lecture you will learn about: Definition, classification and main causes of IDA Factors affecting iron absorption Clinical and hematological findings of IDA. Definition, causes and clinical features of megaloblastic anemia. Sources, requirements and absorption of both vit B12 and folate. Diagnosis of megaloblastic anemia

Definition of anemia

Anemia is defined as a haemoglobin level in blood below the normal level for age and sex. NR Hb level (130-170g/L) in adult male and (120-150g/L) in adult female.

Classification

Morphological classification Normochromic Normocytic Anaemias Hypochromic Microcytic Anaemias Normochromic Macrocytic Anaemias Dimorphic Anaemias. Aetiological classification 1. Anaemia of inadequate red cell production : ( Low Retics ) Stem cell Failure ( Hypoplastic ) Building units deficiency (Iron, B12, folate..etc deficiencies ) Marrow infiltration ( Leukamias, fibrosis). Dyserythropoiesis ( Thalassemia ).

Anaemias of excessive red cell destruction (Haemolytic Anaemias) (High retics) A) Intrinsic red cell defects : Membrane defects : Hb(S) . Hb-Synthesis defects : (Haemoglobinpathies ) Metabolic defects : ( Enzymopathies) B) Extrinsic red cell defects : 1) Immune red cell destruction : Autoimmune : Warm & Cold antibody types Alloimmune : Incompatible blood trans . & HDN Drug related immune haemolysis

2) Non- immune haemolysis : Infections : Malaria , haemorrhagic fever, gas gangrene...Etc. Chemicals : Oxidants Physical agents : Burns. Mechanical haemolysis : MAHA , Cardiac haemolysis. 3. Blood loss.

Iron deficiency anemia (IDA)

Iron deficiency anemia (IDA)
iron deficiency anemia is the most common type of anemia. Causes: blood loss: peptic ulcer, esophageal varices, menstruation. Dietary deficiency: : poverty, religious trends and among vegetarians. Increased demands: pregnancy, lactation, infancy, and adolescence. Malabsorption: gastrectomy, gluten-induced enteropathy.

Iron absorption: Iron absorption occur at duodenum and jejunum parts of small intestine . Iron absorption is favored by Ferrous iron salt. Acidic PH of stomach. Vitamine C intake. Increased animal food. Iron deficiency. Hemorrhage. Ineffective erythropoiesis. Pregnancy.

Iron absorption is reduced by: Decreased haem iron Ferric iron salt Alkalis Tannate in tea Iron overload.

Signs and symptoms of IDA

Pallor Tachycardia/ palpitations Fatigue Pica Tachypnea on exertion Smooth tongue Koilonychia chelosis

Hematological features

Iron deficiency anaemia characterized by Reduction in all red cell indices ( Hb, PCV, MCV, MCH & MCHC ) Peripheral blood: Hypochromia + microcytosis with mild to moderate anisopoikilocytosis Platelets are usually increased but may be normal, WBCs are normal usually

Bone marrow: BM is usually hypercellular Normoblastic erythroid hyperplasia, normoblasts show shaggy outlines and vacuolated cytoplasm with pyknotic nuclei. Other haematopoietic cells are normal. Absent marrow iron both in erythroid cells and macrophages with iron stain.

Diagnosis of iron deficiency anaemia

In most cases: Clinical data. Typical red cell morphology Reduced serum iron &increased TIBC Reduced transferrin saturation S. Ferritin B.M iron assessment (Iron stain)

Megaloblastic Anaemia

Definition

This is a group of anemias in which the erythroblasts in the bone marrow show a characteristic abnormality; maturation of the nucleus being delayed relative to that of cytoplasm. The two principle causes of megaloblastic anemia are folate and B12 deficiency. Both vitamines are required for DNA synthesis.

Causes

Vitamin B12 deficiency. Folate deficiency. Abnormalities of vitamin B12 or folate metabolism. Therapy with antifolate drugs (methotrexate) Therapy with drugs interfering with synthesis of DNA (cytosine arabinoside, hydroxyurea, 6mercaptopurine,azidothymidine). Alcohol.

Clinical features

Obstetric complication and fetal abnormalities particularly in folate deficiency. Gonad is also affected & sterility is common in patients with either deficiency. Maternal folate deficiency has been implicated as a cause of prematurity, folic acid supplement at the time of conception & in the first 12 weeks of pregnancy reduce the incidence of neural tube defects & most of the protective effect can be achieved by taking folic acid 0.4mg daily High serum homocystein lead to thrombotic disease ,dementia and Alzheimer disease..

Haematological features

The anemia is macrocytic (increased MCV ) Peripheral blood: RBCs: macrocytosis, characteristically oval in shape with marked red cell distortion ( anisopoikilocytosis ). WBCs: usually reduced in number with hypersegmented neutrophiles Pancytopenia ( usual in severe cases ).

Bone marrow

Hypercelluar bone marrow with erythroid hyperplasia. Erythroid cells show megaloblastic features: large cells with immature nuclear development. Nuclear cytoplasmic dissociation (cytoplasmic maturation is normal but nuclear remnants) giant metamyelocytes or stab cells. Megakaryocytes may be large and hyperpolypoid.

Sources and requirements

Vitamin B12 is found in some foods like meat, fish, eggs, and milk.Daily requirements 1 – 3 μg.Stores ( mainly in the liver ).Stored B12 is sufficient for 3-4 years if supplies are cut off completely.


Absorption of B12
Minor amounts are absorbed passively ( 1%). The normal mechanism is through combination with gastric intrinsic factor ( IF ), absorption is through special receptors at the terminal ileum. B12 is carried to target organs by special protein known as transcobalamins.

Causes of B12 deficiency

1- Nutritional (especially vegans). 2- Malabsorption: A-gastric causes: Perinicious anemia. Congenital intrinsic factors deficiency. Total or partial gastrectomy.

B- intestinal causes: blind loop syndrome. Jujinal diverticulosis. Iloecaecal fistula. Anatomical blind loop. Intestinal stricture. Ileal resection. Crohn’s disease.

Folate DeficiencySources and requirements:Unlike B12 folates are present in both plant and animal origin foods.Daily requirements are about 100 μgBody stores, mainly in the liver.Stores are sufficient for about 4 months.

Absorption and transport of folates. Absorption is from upper third of small intestine, the exact mechanism is not known whether it is an active or facilitated diffusion. In the plasma about 2/3 are free and 1/3 loosely attached to albumin, mostly in the form of methyl tetra hydro folate. Causes of folate deficiency Dietary deficiency. Alcohol drinking. Infants with kwashiorkor, repeated infections and those fed on goat milk.

Malabsorption :Gluten enteropathy.As a congenital defect “ selective folate malabsorption “.Drugs as salazopyrine.Excess utilization:Pregnancy.(requirement 200-300Mg & to400Mg)Prematurity.Chronic haematological diseases.Chronic dialysis.Antifolate drugs: antiepileptic, alcohol, methotrexate.

Thanks