Erythrocyte Disorders (2).pptx FOR [PST RN

rythrocyte Disorders (2).pptx FOR [PST RN

1. Erythrocyte Disorders By Saiqa Perveen Health Educator

2. Anemias Anemia means deficiency of hemoglobin in blood than reference level e.i. , below 130g/L in men & 115g/L in women. Inability of blood to carry enough oxygen to meet body needs. Global issue, prevalence b/w ¼ to 1/3 of world pop. Causes of Anemia: Production of insufficient number of RBC’s due to bone marrow failure (Aplastic anemia). Formation of defective erythrocytes due to nutritional deficiency e.g., iron deficiency anemia, vit.B12 or folic acid deficiency anemia. Anemia due to hemorrhage or Blood loss. Anemia due to hemolysis.

3. Sign & symptoms Pallor Fatigue Breathlessness on exertion Tachycardia-increased heart rate to improve blood flow Palpitations or angina pectoris (chest pain or discomfort due to overwork of heart muscle). Loss of appetite Koilonychia- spoon shaped nails seen in iron deficiency anemia. Jaundice in hemolytic anemia.

4. Iron deficiency Anemia Most common form globally. Daily iron requirement in men 1-2 mg & 3 mg in women due to loss during menstruation & pregnancy. Children require more than adults to meet growth requirements. Dietary iron comes from red meat, fortified cereals & highly colored vegetables. Only 10 % dietary iron is absorbed. RBC’s count often normal but they are microcytic, Hypochromic. Mean cell hemoglobin(MCH) less than 27 pg /L. Severe when Hb below 9g/100 ml blood.

5. Causes of Iron deficiency Anemia Iron deficiency anemia may be due to 3 reasons: Deficient intake High requirements Malabsorption Deficient Intake Poorly planned vegetarian diets. Wt. reducing diets containing small range of foods. Babies dependent on milk may suffer mild iron deficiency anemia if weaning on to a mixed diet is delayed much past ist yr. b/z child’s liver carry only a few months’ store of iron & milk is poor source of iron. Older adults with poor diet Alcohol dependent

6. High Requirements In pregnancy iron requirements are increased to support fetal growth & additional load on mother’s CVS. Chronic blood loss e.g., peptic ulcers, heavy menstrual bleeding( menorrhagia), haemorrhoids . Regular aspirin intake Gastrointestinal cancer Children have high requirement than adults & their iron intake may be restricted if they are fussy eaters or raised on poor quality diet.

7. Malabsorption Iron absorption is dependent on an acid environment, an increase in gastric pH may reduce iron absorption. It may be due to: Excessive use of antacids Removal of part of stomach Parietal( acid releasing cells of stomach lining) are destroyed as in pernicious anemia Loss of surface area for absorption in intestine e.g., after surgical removal.

8. Megaloblastic Anemia Deficiency of vit. B-12, folic acid or intrinsic factor impairs erythrocyte maturation & abnormally large RBCs (megaloblasts ) appear in blood. During normal erythropoiesis, several cell divisions occur & daughter cells at each stage are smaller than parent cell. In vit.B-12/folic acid deficiency anemia, rate of RNA & DNA synthesis are reduced, delaying cell division & cells grow larger than normal b/w divisions. They are immature & some are nucleated ( MCV> 94fL) Hb content of each cell is normal or raised. Cells have fragile membranes & their life span reduced b/w 40-50 days Reduced production & early lysis cause anemia.

9. Pernicious Anemia Caused by lack of intrinsic factor released from parietal cells of gastric mucosa & required to absorb vit. B12 of food. Causes: Autoimmune disease in which autoantibodies destroy intrinsic factor & gastric parietal cells. Gastrectomy leaves fewer cells to produce Intrinsic Factor. Chronic gastritis, malignant disease & ionizing radiations damage gastric mucosa & parietal cells that produce Intrinsic Factor.

10. Other causes of VIT. B-12 deficiency: Dietary deficiency of vit. B-12: Vit. B-12 is widely available in animal derived foods e.g., dairy products, meat & eggs. So deficiency is rare except in strict vegans. Liver has extensive stores, so deficiency takes several years to appear. Malabsorption- if terminal ilium removed or inflamed e.g., in Crohn’s disease, vit. B12 can’t be absorbed despite normal Intrinsic Factor level. Consequences of Vit. B 12 deficiency anemia: As it is required in myelin production specific feature is neurological involvement like numbness & decreased sensation in feet & fingers.

11. Aplastic Anemia Due to lack of functioning of bone marrow. Causes: Exposure to high dose radiation or chemotherapy for cancer treatment can damage stem cells of bone marrow. High doses of certain toxic chemicals e.g., insecticides or benzene in gasoline In autoimmune disorders e.g., lupus erythematosus, immune system begins attacking healthy cells such as bone marrow stem cells. In half of Aplastic anemia cause is unknown(idiopathic aplastic anemia) Treatment: Blood transfusion Bone marrow transplantation

12. Blood loss Anemia After rapid hemorrhage, body replaces plasma in 1-3 days. If a 2 nd hemorrhage does not occur, RBC’s conc. Returns to normal within 3-6 weeks. In chronic blood loss, a person can’t absorb iron from intestine to form Hb lost giving rise to microcytic, hypochromic anemia .

13. Hemolytic Anemias Erythrocyte breakdown increased beyond normal. Lifespan can be as little as 24 hrs. If mild, bone marrow may increase RBC’s production to compensate without anemia. Most hemolysis takes place in spleen & liver causing splenomegaly & jaundice. Congenital Hemolytic Anemias Sickle cell anemia Thalassaemias

14. Sickle cell anemia RBC’s have abnormal type of hemoglobin S , containing faulty beta chains( amino acid valine substituted by glutamic acid) . At low O2 conc. Hb. precipitates into long crystals inside RBC’s & they become sickle-shaped with highly fragile membrane leading to hemolysis & anemia. Sickle cells don’t move smoothly through circulation, obstruct blood flow leading to intravascular clotting, tissue ischemia & infarction. Such pt. experience a vicious circle of sickle cell disease “crisis” in which low O2 tension in tissues causes sickling & rupture of RBC’s which causes more decrease in O2 & RBC’s destruction. This process progresses rapidly & causes death within few hours due to serious decrease in RBC’s. Long-term problems include: cardiac disease, kidney failure, retinopathy, poor tissue healing, slow growth in children, brain stroke & seizures. If a person has one faulty gene , said to be carrier or have sickle cell trait & mildly symptomatic. For sickle cell disease a person must receive faulty gene from both parents.

15. Thalassaemia Genetic defect caused by excessive synthesis & accumulation of one of globin chains used in Hb production, damaging developing RBC’s & resulting hemolysis. Anemia may be mild & asymptomatic to profound & life threating. Symptoms in moderate to severe cases include bone marrow expansion & splenomegaly. In severe form regular blood transfusion is required leading to iron overload.

16. Hemolytic disease of newborn Rh _ mother has no Rh antigen but can produce anti-Rh antibodies. If fetus has Rh+ antigen from father, placenta protects baby from mother immune system during ist pregnancy. During delivery, a few RBC’s may enter mother circulation leading to production of anti Rh antibodies. In subsequent Rh+ baby, anti-Rh antibodies may cross placenta into fetus’s blood & cause its agglutination. Agglutinated RBC’s hemolyse releasing Hb into blood which is converted by macrophages into bilirubin causing jaundice. Baby is anemic at birth & anti Rh antibodies circulate in infant’s blood for 1-2 months after birth destroying more RBC’s. Hematopoitic tissues of infant attempt to replace hemolyzed RBC’s. Liver & spleen become enlarged. Because of rapid production, many early nucleated blastic RBC’s pass from bone marrow into blood. Due to their presence disease is called erythroblastosis fetalis. Usually severe anemia causes death. Children who survive exhibit permanent mental impairment or damage to motor areas of brain due to precipitation of bilirubin in neuronal cells causing their destruction a condition called kernicterus.

17. Treatment of erythroblastotic neonate: one treatment is to replace neonates blood with Rh - blood. About 400 ml Rh negative blood is infused over a period of 1.5 or more hour while neonates own Rh positive blood is being removed. It is repeated several times during ist few weeks of life to keep bilirubin level low. By the time, these transfused Rh negative cells are replaced with infants own Rh positive cells, a process that requires 6 or more weeks, anti-Rh antibodies that have come from mother will have been destroyed. Prevention: Anti-D antibody is administered to expectant mother at 28-30 weeks of gestation. Rh- mother is given anti-Rh antibodies injection within 72 hours of delivery of Rh+ baby, fetal antigens are destroyed before mother immune system detects Rh antigens & subsequent pregnancies are not affected.

18. Acquired haemolytic anemias Blood transfusion reactions: If a person receives blood carrying antigen different from their own immune system, RBC’s of donor blood are agglutinated. Agglutinated cells are phagocytosed & Hb released is converted to bilirubin causing jaundice. If liver function is normal bilirubin is converted to bile & jaundice does’t appear unless more than 400 ml of blood is hemolyzed in less than a day. Breakdown products will block filtering mechanism of nephrons causing kidney failure & triggering formation of multiple clots throughout circulatory system called disseminated intravascular coagulation(DIC) . Chemical agents that cause hemolysis: some drugs when taken in large dose for long time e.g., sulphonamides . chemicals e.g., lead, arsenic. Microbial toxins e.g., Streptococcus pyogens , Clostridium perfringens.

19. Effects of Anemia on circulatory system Viscosity of blood depends on conc. Of RBC’s. In severe anemia, blood viscocity may fall to 1.5 times that of water than normal value of 3. this decreases resistance to blood flow in peripheral blood vessels lead to increased blood flow through tissues & return to heart thereby greatly increasing cardiac output. Hypoxia also causes dilation of peripheral blood vessels increasing return of blood to heart & increased cardiac output sometimes 3-4 times normal & increased pumping workload on heart. These two offset reduced oxygen carrying effect of anemia But when an anemic person exercises, increased tissue demand for oxygen leads to extreme tissue hypoxia. Heart is not capable to pump much greater quantities of blood than it is already pumping & acute cardiac failure may occur.

20. Polycythemia Secondary polycythemia: whenever tissues become hypoxic, bone marrow automatically produces large quantities of extra RBC’s called secondary polycythemia. RBC’s count commonly rises to 6-7 million/mm 3 (30 % above normal). Causes: Too little O 2 in breathed air such as at high altitude (14000-17000 ft.) Failure of O 2 delivery to tissues as in cardiac failure.

21. Polycythemia Vera (Erythremia): Pathological condition in which RBC’s count may be 7-8 million/mm 3 & hematocrit 60-70 %. Cause: Genetic aberration in hemocytoblastic cells that produce blood cells. They don’t stop producing red cells when too many cells already present. It usually causes excess production of WBC’s & platelets as well. Features: Total blood volume increases on some occasions to almost normal. Due to increased blood viscocity , entire vascular system becomes intensely engorged. Many capillaries become plugged by viscous blood. Viscosity sometime increases from normal 3 times viscosity of water to 10 times that of water.