Medicine 5th year, 8th lecture/part three (Dr. Sabir)

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The lecture has been given on Apr. 3rd, 2011 by Dr. Sabir.

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Medicine 5th year, 8th lecture/part three (Dr. Sabir)

  1. 1. Sickle Cell Anemia Dr. Sabir
  2. 2. What is Sickle Cell Anemia (SCA)? <ul><li>an inherited condition that results in a decrease in the ability of red blood cells to carry oxygen throughout the body </li></ul><ul><ul><li>Sickle red blood cells become hard and irregularly shaped (resembling a sickle) </li></ul></ul><ul><ul><li>Become clogged in the small blood vessels and therefore do not deliver oxygen to the tissues. </li></ul></ul><ul><ul><li>Lack of tissue oxygenation can cause excruciating pain, damage to body organs and even death. </li></ul></ul>
  3. 3. Pathogenesis <ul><li>Normal hemoglobin </li></ul><ul><li>2 alpha and 2 beta chains </li></ul><ul><li>form a 4 chain tetramer </li></ul><ul><li>HbS: </li></ul><ul><li>Valine substituted for glutamic acid in both beta chains (HbSS). </li></ul><ul><li>This occurs due to single point mutation at sixth position of beta globin chain which has thymine instead of adenine. </li></ul>
  4. 4. PATHOGENESIS Arterial pO 2 oxyHbS(soluble) Stiff,viscous sickle cell Venous pO 2 deoxyHbS polymerised) Membrane changes Ca 2+ influx,K + leakage Capillary venule occlusion Shortened red cell survival Microinfarction Ischemic tissue pain Ischemic organic malfn. Anemia, jaundice
  5. 5. Mechanism -HbS <ul><li>When sickle haemoglobin (HbS) gives up its oxygen to the tissues, HbS sticks together </li></ul><ul><ul><li>Forms long rods inside RBC </li></ul></ul><ul><ul><li>RBC become rigid, inflexible, and sickle-shaped </li></ul></ul><ul><ul><li>Unable to squeeze through small blood vessels, instead blocks small blood vessels </li></ul></ul><ul><ul><li>Less oxygen to tissues of body </li></ul></ul><ul><li>RBCs containing HbS have a shorter lifespan </li></ul><ul><ul><li>Normally 120 days </li></ul></ul><ul><ul><li>Chronic state of anaemia </li></ul></ul>
  6. 6. <ul><li>Sickle Cell Trait </li></ul><ul><li>Sickle haemoglobin (S) + Normal haemoglobin (A) in RBC </li></ul><ul><ul><li>Adequate amount of normal Hb (A) in red blood cells </li></ul></ul><ul><ul><ul><li>RBC remain flexible </li></ul></ul></ul><ul><ul><ul><li>Carrier </li></ul></ul></ul><ul><ul><ul><li>Do Not have the symptoms of the sickle cell disorders, with 2 exceptions </li></ul></ul></ul><ul><ul><ul><li>Pain when Less Oxygen than usual (scuba diving, activities at high altitude (12,000ft), under general anaesthesia) </li></ul></ul></ul><ul><ul><ul><li>Minute kidney problems </li></ul></ul></ul>
  7. 7. LAB DIAGNOSIS <ul><li>SICKLE TEST: Red cells with HbS take a sickle shape when mixed with a freshly prepared solution of the reducing agent sodium metabisulphite.(2%) Giving an appearance of turbidity. </li></ul><ul><li>SOLUBILITY TEST: Hb added to solution of sodium dithionite(reducing agent) in phosphate buffer.Turbidity shows presence of HbS. </li></ul><ul><li>Hb ELECTROPHORESIS </li></ul>
  8. 8. BLOOD PICTURE <ul><li>Hb : 6-9gm%, may be lower </li></ul><ul><li>Anemia: normocytic, normochromic </li></ul><ul><li>MCV,MCH: Normal </li></ul><ul><li>Stained film:Moderate anisopoikilocytosis, sickle cells, oval cells, occ target cells, Howell-Jolly bodies </li></ul><ul><li>Reticulocytosis (10-20%) </li></ul>
  9. 10. Screening <ul><li>Haemoglobin Electrophoresis </li></ul><ul><ul><li>Simple Blood test </li></ul></ul><ul><ul><li>Routine screening in high risk groups </li></ul></ul><ul><ul><ul><ul><li>During pregnancy </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Before anaesthesia </li></ul></ul></ul></ul><ul><li>Prenatal Testing </li></ul><ul><ul><li>Amniocentesis </li></ul></ul><ul><ul><ul><li>16 and 18 weeks of the pregnancy </li></ul></ul></ul><ul><ul><ul><li>small risk of causing a miscarriage (1 in 100) </li></ul></ul></ul><ul><ul><li>Chorionic villus sampling (CVS) </li></ul></ul><ul><ul><ul><li>9th or 10th week of pregnancy </li></ul></ul></ul><ul><ul><ul><li>very small amount of material from the developing placenta </li></ul></ul></ul><ul><ul><ul><li>slightly higher chance of miscarriage </li></ul></ul></ul>
  10. 11. Early Symptoms and Complications <ul><li>Typically appear during infant's first year </li></ul><ul><ul><ul><li>1 st symptom: dactylitis and fever (6 mo-2 yrs) </li></ul></ul></ul><ul><ul><ul><li>Pain in the chest, abdomen, limbs and joints </li></ul></ul></ul><ul><ul><ul><li>Enlargement of the heart, liver and spleen nosebleeds </li></ul></ul></ul><ul><ul><ul><li>Frequent upper respiratory infections </li></ul></ul></ul><ul><ul><ul><li>Chronic anemia as children grow older </li></ul></ul></ul><ul><li>Over time Sickle Cell sufferers can experience damage to organs such as liver, kidney, lungs, heart and spleen </li></ul><ul><li>Can result in death </li></ul>
  11. 12. Medical Complications <ul><li>pain episodes </li></ul><ul><li>strokes </li></ul><ul><li>increased infections </li></ul><ul><li>leg ulcers </li></ul><ul><li>bone damage </li></ul><ul><li>jaundice </li></ul><ul><li>early gallstones </li></ul><ul><li>lung blockage </li></ul><ul><li>kidney damage and </li></ul><ul><li>loss of body water in urine </li></ul><ul><li>painful erections (priapism) </li></ul><ul><li>blood blockage in the spleen or liver (sequestration) </li></ul><ul><li>eye damage </li></ul><ul><li>low red blood cell counts (anemia) </li></ul><ul><li>delayed growth </li></ul>
  12. 13. Serious Complications: PAIN Recurrent Pain Episodes or Sickling Crises <ul><li>Occur at any age but appear to be particularly frequent during late adolescence and early adult life </li></ul><ul><ul><li>Unpredictable </li></ul></ul><ul><ul><li>Red Blood Cells get stuck in the small veins and prevent normal blood flow </li></ul></ul><ul><ul><li>Characterized by severe pain in the back, chest, abdomen, extremities, and head </li></ul></ul><ul><ul><li>Highly disruptive to life </li></ul></ul><ul><ul><li>Most common reasons for individuals to seek health care </li></ul></ul>
  13. 14. <ul><li>Fever </li></ul><ul><li>Chest pain </li></ul><ul><li>Shortness of Breath </li></ul><ul><li>Increasing tiredness </li></ul><ul><li>Abdominal swelling </li></ul><ul><li>Unusual headache </li></ul>Danger Signs of a Crisis <ul><li>Any sudden weakness or </li></ul><ul><li>loss of feeling </li></ul><ul><li>Pain that will not go away </li></ul><ul><li>with home treatment </li></ul><ul><li>Priapism (painful erection </li></ul><ul><li>that will not go down) </li></ul><ul><li>Sudden vision change </li></ul>SEEK URGENT HOSPITAL TREATMENT IF IN CRISIS
  14. 15. Crises <ul><li>During a crisis </li></ul><ul><ul><li>severe pain in the fingers, toes, </li></ul></ul><ul><ul><li>arms, joints,legs, back, abdomen, and bones. </li></ul></ul><ul><li>Decrease in oxygen to the chest and lungs </li></ul><ul><ul><li>May lead to acute chest syndrome </li></ul></ul><ul><ul><ul><li>Damage to the lungs </li></ul></ul></ul><ul><ul><ul><ul><li>Severe pain and fever </li></ul></ul></ul></ul><ul><ul><ul><ul><li>airways narrowing, further reducing O 2 </li></ul></ul></ul></ul><ul><ul><ul><li>Leads to an increased risk of potentially </li></ul></ul></ul><ul><ul><ul><li>fatal infections </li></ul></ul></ul>
  15. 16. <ul><li>Infections </li></ul><ul><li>Thirst and dehydration caused by not drinking enough( even if thirst is not felt ) </li></ul><ul><li>Over-exertion </li></ul><ul><li>Over-excitement </li></ul><ul><li>Cold weather and cold drinks and swimming </li></ul><ul><li>Bangs, bumps, bruises and strains </li></ul><ul><li>Stress triggers pain in adults, but does not seem to do so in children. </li></ul>Triggers of Pain
  16. 17. Alleviating Pain <ul><li>Warmth: increases blood flow </li></ul><ul><li>Massaging and rubbing </li></ul><ul><li>Heat from hot water bottles and deep heat creams </li></ul><ul><li>Bandaging to support the painful region </li></ul><ul><li>Resting the body </li></ul><ul><li>Getting the sufferer to relax </li></ul><ul><ul><li>deep breathing exercises </li></ul></ul><ul><ul><li>distracting the attention </li></ul></ul><ul><li>Pain-killing medicines (analgesics): paracetamol, codeine non-steroidal anti-inflammatory, morphine if necessary </li></ul>
  17. 18. <ul><li>Taking folic acid daily to help make new red cells </li></ul><ul><li>Daily penicillin until age six to prevent serious infection </li></ul><ul><li>Drinking plenty of water daily (8-10 glasses for adults) </li></ul><ul><li>Avoiding too hot or too cold temperatures </li></ul><ul><li>Avoiding over exertion and stress </li></ul><ul><li>Getting plenty of rest </li></ul><ul><li>Getting regular check-ups from knowledgeable health care providers </li></ul>Daily Preventive Measures
  18. 19. Treating Complications <ul><li>Pain-killing drugs and oral and intravenous fluids </li></ul><ul><ul><li>To reduce pain and prevent complications. </li></ul></ul><ul><li>Transfusions </li></ul><ul><ul><li>Correct anemia </li></ul></ul><ul><ul><li>Treat spleen enlargement in children before the condition becomes life-threatening </li></ul></ul><ul><ul><li>Regular transfusion therapy also can help prevent recurring strokes in children at high risk of crippling nervous system complications. </li></ul></ul>
  19. 20. <ul><li>Hydroxyurea </li></ul><ul><ul><li>The first effective drug treatment for adults with severe sickle cell anemia reported in early 1995 </li></ul></ul><ul><ul><li>Daily doses of the anticancer drug, hydroxyurea, reduced the frequency of painful crises, acute chest syndrome, needed fewer blood transfusions </li></ul></ul><ul><ul><li>Increases production of fetal hemoglobin in the blood </li></ul></ul><ul><ul><ul><li>Fetal hemoglobin seems to prevent sickling of red cells </li></ul></ul></ul><ul><ul><ul><li>cells containing fetal hemoglobin tend to survive longer in the bloodstream </li></ul></ul></ul>Developing Treatments
  20. 21. <ul><li>Bone marrow transplantation </li></ul><ul><ul><li>Shown to provide a cure for severely affected children with sickle cell disease </li></ul></ul><ul><ul><li>Only about 18 percent of children with sickle cell anemia are likely to have a matched sibling. </li></ul></ul>Developing Treatments
  21. 22. <ul><li>The Ultimate Cure? </li></ul><ul><li>Gene Therapy </li></ul><ul><li>Correcting the “defective gene” and inserting it into the bone marrow </li></ul><ul><li>Turning off the defective gene and simultaneously reactivating another gene that turns on production of fetal hemoglobin. </li></ul><ul><li>No real cure for Sickle Cell Anemia at this time. </li></ul><ul><li>“ In the past 30 years, the life expectancy of people with sickle cell anemia has increased. Many patients with sickle cell anemia now live into their mid-forties and beyond.” </li></ul>

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