SICKLE CELL ANEMIA

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By: kiragumacharia (17 month(s) ago)

Your powerpoint presentation is great ,would you please allow me to download this presentation? Thank you

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Sickle Cell Anemia Dr Ashok Mahato

What is Sickle cell anemia ? : 

What is Sickle cell anemia ? It is a type of Haemoglobinopathy. Inherited as an autosomal recessive genetic disease & result from substitution of aminoacid valine from glutamic acid in position 6 of Beta globin chain leading to production of defective form of haemoglobin [ HbS ] HbS is a structurally & qualitatively defective Hb.

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SC Hb affects the normal O2 carrying capacity of RBC’s . When these Sickle cells are de-oxygenated under stress , the RBC’s change from round flexible disc-like cells to elongated sickle / crescentic moon shape. Effect is that the cells do not pass freely through small capillaries & form clusters, which block the blood vessels. This blockage prevents oxygenation of the tissues in the affected areas resulting in tissue hypoxia & consequent pain known as sickle cell crisis/pain

The Proteins of Hemoglobin A : 

The Proteins of Hemoglobin A There are 4 protein subunits of Hemoglobin A There will be different forms of Hemoglobin when there is a mutation in the beta subunit.

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Homozygotes only produce abnormal beta chains & make haemoglobin S [ HbS, termed SS ] & this result in clinical syndrome of sickle cell disease. Heterozygotes produce a mixture of normal & abnormal beta chains that make normal HbA & HbS [ termed AS ] & results in clinically asymptomatic Sickle cell trait.

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AS AS SS AS AS AA Normal Sickle – cell trait Sickle - cell disease Possible genotype of offspring of parents with Sickle – cell trait

Pathogenesis : 

Pathogenesis Deoxygenation leads to hydrophobic interaction between adjacent Hb S molecules. Distortion of Red cell membrane produce sickle shaped cells Rapid haemolysis Decreased elasticity of cell wall of RBC Decreased life span 10 – 20 days. Clogging of RBC in microcirculation.

Red blood cells Going through Vessels : 

Red blood cells Going through Vessels

Clinical features : 

Clinical features Sickling is precipitated by hypoxia , acidosis dehydration & infection. Irreversibly sickled cells have a shortened survival & plug vessels in microcirculation. Acute syndrome of plugging of RBC’s in Vessels is 1. Vaso-occlusive crisis. 2. Aplastic crisis 3. Sequestration crisis. 4. Sic kle chest synd.

Acute crisis : 

Acute crisis Vaso-occlusive crisis – plugging of small vessels in bone produces severe pain in humerus , femora, ribs, spine. Plugging in hands & feet of children causes dactylitis. It is most common crisis. Sickle chest syndrome – common cause of death in adult. Bone marrow infarction results fat emboli to lungs which causes pulmonary infartion & ventilatory failure.

Acute crisis : 

Acute crisis Sequestration crisis – Thrombosis of venous outflow of organ causes acute painful enlargement & loss of function. In children massive enlargement of spleen result in severe anemia & circulatory collapse with death. Recurrent sickling & infarction of spleen in adults may have no functional spleen & is called autosplenectomy.

Acute crisis : 

Acute crisis Aplastic crisis – Infection of adult sicklers with human erythrovirus 19 result in severe but self limiting red cell aplasia. This produces very low Hb which may cause heart failure.

Clinical manifestation of SCD : 

Clinical manifestation of SCD Ocular- Background retinopathy, Proliferative retinopathy, Vitreous bleed. Renal – Enuresis, haematuria, papillary necrosis, CRF. Bone -- Dactilytis, arthropathy, osteomyelitis avascular necrosis, vertebral collapse CNS – CVA, Fits, Subarachnoid bleed. Cardiac – Sickle myocardium, cardiomegaly transfusional iron overload.

Clinical manifestation : 

Clinical manifestation Priapism. Splenic infarction. Cholelithiasis. Leg ulceration Pulmonary infarction

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X-ray of a hand of young baby swollen from dactylitis Enlarged & unhealthy spleen with SCD

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Adolescents and adults can develop ulcers on their legs

Why Sickle Cell Trait are resistant to Malaria ? : 

Why Sickle Cell Trait are resistant to Malaria ? When Hb of Sickle Cell carriers come in contact with the Malaria parasite they become sickled. When sickled cell pass through the spleen, the cells are eliminated with the Malaria parasite. Sickle Cell trait causes the parasite to stay in the body for an extended period of time, so it is able to build up a defense to it. 3. As O2 concentration is low in the spleen, infected trapped cells in the spleen are destroyed 4. Malaria parasite produces lactic acid in RBC . This causes the RBC to polymerize & sickling. sickled cells are then destroyed in the spleen.

Investigation : 

Investigation Screening test – Demonstrated by exposing RBC to a reducing agent such as Sodium dithionte ; HbA gives clear solution but HbS polymerises to produce a turbid solution. Hb electrophoresis – Gives a definitive diagnosis. HPLC [ High performance liquid chromatography] to quantify the amount of sickled cell. Blood film shows compensated anemia with Hb % 6-8gm. Features of Hyposlenism – target cell Howell- jelly bodies.

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Screening Haemoglobin Electrophoresis Simple Blood test Routine screening in high risk groups During pregnancy Before anaesthesia Prenatal Testing Amniocentesis 16 and 18 weeks of the pregnancy small risk of causing a miscarriage (1 in 100) Chorionic villus sampling (CVS) 9th or 10th week of pregnancy very small amount of material from the developing placenta slightly higher chance of miscarriage

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Early Symptoms & Complication Typically appear during infant's 1st Yr 1st symptom: dactylitis & fever [6 mo - 2 yrs ] Pain in the chest, abdomen, limbs & joints Enlargement of the heart, liver & spleen Frequent upper respiratory infections Chronic anemia as children grow older

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Recurrent Pain Episodes / Sickling Crises Occur at any age but appear to be particularly frequent during late adolescence & early adult life. RBC get stuck in the small veins & prevent normal blood flow. Characterized by severe pain in the back, chest, abdomen, extremities, & head. Highly disruptive to life Most common reasons for individuals to seek health care

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Infectious complications Prominent early in life Leading cause of morbidity and mortality Good prognosis in newborn if screening for SCD is early with vaccination for childhood illnesses, use of prophylactic antibiotics, & aggressive diagnosis & T/t of febrile events. Acute splenic sequestration Episodes of rapid increase in splenic size & decrease in Hb . High morbidity & mortality early in life for children with SCA & at any age for those with SCD. Serious Complications

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Strokes Up to 15% of children may have overt or silent strokes during childhood Chronic transfusion therapy reduces the recurrence rate of overt stroke & keeping HbS level below 30%. Bone disease Early Osteomyelitis. Painful inflammatory disease of bone,often bacterial in origin & may result in death of bony tissues. Avascular necrosis of the femur & humerus Death of bone tissue due to disrupted blood supply Marked by severe pain in the affected region & by weakened bone that may flatten & collapse. Serious Complications

Serious Complications : 

Serious Complications Leg ulcers Seen in patients older than 10 years of age Resistant to therapy and cause significant morbidity Ophthalmic complications Proliferative retinopathy, vitreous hemorrhage, & retinal detachment Priapism Distressing complication, occurs at all ages,difficult to treat & Causes a high incidence of impotence. Chronic Anemia Associated with fatigue, irritability, jaundice, pain, delayed puberty, leg sores,

Pregnancy & SC disease : 

Pregnancy & SC disease Higher rate of spontaneous abortion. A miscarriage may happen up to 25% of the time. Higher rate of babies not surviving to birth or being stillborn. 8-10% . Birth weight is lower than average. Infection is more common in women with SCD during pregnancy, especially bladder infection. Increased chance of PIH and preeclampsia Increased incidence of PPH.

Slide 26: 

Fever Chest pain Shortness of Breath Increasing tiredness Abdominal swelling Unusual headache Danger Signs of a Crisis 7. Sudden diminished vision. 8. sudden weakness of limbs. Priapism [ painful erection that will not go down ] SEEK URGENT HOSPITAL T/t IF IN CRISIS

Slide 27: 

Infections Thirst & dehydration caused by not drinking enough water even if thirst is not felt. Over-exertion Over-excitement Cold weather & cold drinks & swimming Laceration ,bruises , strains & sprains . Stress triggers pain in adults, but does not seem to do so in children. Triggers of Pain

Management of VOC : 

Management of VOC All voc are managed by aggressive rehydration O2 therapy , adequate analgesia [ opiates] antibiotics & BT where ever possible. Regular transfusion programme to supress HbS level below 30% is indicated in CVA in children. Prophylaxis with daily Folic acid & Penicillin V to protect against pneumococcal infection. Vaccination against Pneumococcus, Haemophilus influenzae B & Hepatitis B.

Slide 29: 

Alleviating Pain Warmth: increases blood flow Massaging and rubbing Heat from hot water bottles & deep heat creams Bandaging to support the painful region Resting the body to relax. Getting the sufferer to relax deep breathing exercises distracting the attention. Analgesics : NSAIDs / Morphine if necessary.

Slide 30: 

Folic acid daily to help make new red cells Daily penicillin until age six to prevent serious infection Drinking plenty of water daily (8-10 glasses for adults) Avoiding too hot or too cold temperatures Avoiding over exertion and stress Getting plenty of rest . Daily Preventative Measures

Slide 31: 

Child encouraged to participate in sports, but not pushed passed their limitations If they are in pain or feel tired they should be allowed to rest and keep warm. They should have access to drinks. Strenuous exercise, dehydration and cold can induce a crisis. Strenuous outdoor activities should be avoided in cold or wet weather Should only swim if the water is warm and care is taken to keep warm when leaving the water If develops a crisis despite these precautions he or she should avoid swimming all together Psychosocial Issues

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Hydroxyurea Effective drug T/t for adults with severe SCA. Daily doses of the anticancer drug, hydroxyurea, reduces the frequency of painful crises, acute chest syndrome & need fewer Bld trasfn . Increases production of Fetal Hb in the blood. Fetal Hb seems to prevent sickling of RBCs. Cells containing Fetal Hb tend to survive longer in the bloodstream Long term T/t

Bone Marrow Transplant : 

Bone Marrow Transplant Bone marrow transplant is the closest thing possible to the cure of SSA. Helps in production of healthy RBC from transplanted bone marrow The success rate is 90 – 95%

Gene Therapy : 

Gene Therapy Gene therapy is a relatively new idea of inserting genes into the cells of an individual in order to treat hereditary disease such as SSA, in which a defective mutants alleles is replaced with a functional one. Gene therapy would be the best cure for SSA in future, as of now it is on it’s experimental stage.

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Thank You