Other haem Flashcards
Sickle cell
- definition
- risk factors
- symptoms
- signs
- ix
- acute manifestations
- long term complications
- mx
- extra facts
- Definition: an inherited hemoglobinopathy where autosomal recessive mutation in beta globin gene which encodes haemoglobin beta subunit. Life expectancy is 58 years
- Pathophysiology: Normal haemoglobin has 4 globin chains + 4 haem molecules - Normal HbA has 2 alpha and 2 beta chains. GAG to GTG nucleic acid substitution causing glutamic acid to valine which results in a HbS allele. If one allele then a carrier (HbAS) (assymp) and if homozygous (HbSS) then sickle cell disease. In deoxygenated state HbS tetramers bind to each other and can polymerise distorting the shape + becomes rigid. The abnormal shape makes it more fragile leading to haemolytic anaemias
- Risk factors: black african/caribbean, asian, STRONG family history
- Symptoms: intermittent acute pain vaso-occlusion (back, legs, knee) precipitated by hypoxia/infection, exercise, dehydration. Dactylitis
- Signs: pallor, fatigue (anaemia), jaundice (hemolysis), fever, digital redness, tachycardia, tachypnoea
- DD: gout, pancreatitis, appendicitis, cholecystitis
- Investigations: antenatal screening, newborn blood spot test, haemoglobin electrophoresis (appears around 6 months when HbF decreases), high performance liquid chromatography, blood film (nucleated rbc, howell jolly bodies, sickle shaped rbcs), bloods (fbc, reticulocyte count, iron studies), xray long bones (infarctions), cxr (infiltrates may indicate acute chest syndrome)
- acute manifestations: acute chest syndrome, vasoocclusive crisis, sickle cell crisis, spleen sequestration, priapism
AVN - vaso-occlusive crisis where blood cells clog in capillaries causing distal ischaemia causing swelling + fever
Spleen sequestration crisis: rbc block flow in spleen so enlarges + pooling blood = severe anaemia + hypovolaemic shock where blood transfusions and fluid needed. Can lead to spleen infarction and hyposplenism inc risk to encapsulated bacteria (strep pneum, haem influ)
Acute chest syndrome: vessels in lung clogged (sob, fever, pain, hypoxia, pul infiltrates) - analgesia, hydration, blood transfusions, abx, oxygen, ventilation
Sickle cell/ Acute pain crisis - paracet/nsaids, fluids, oxygen, opiates, abx. Advice to avoid alc, strenuous ex, stay warm, abx prophylaxis penicillin V
aplastic crisis when parvovirus infection causing bm stop functioning
- long term complications: delayed puberty, pul htn, stroke, adenotonsillar hypertrophy, cardiomeg, hf, renal dysfunction , leg ulcers, aplastic crisis (parvovirus b19)
- Management:
Prophylactic treatment - hydroxycarbamide (stimulates HbF), blood transfusions, bm transplant curative
Other - Flu jab annual, pneumococcal every 5 years, hep b if receiving as chronic sleep damage due to infarction causing increased susceptibility to infections
-
Extra facts
Common causes of death are stroke, infection (pneumonia, meningitis, sepsis) in children
HbS allele is survival adv against plasmodium falciparum in carriers hence selective advantage to pass on this mutation in areas of high malaria such as africa
b thalassemia
- definition
- symptoms
- mx
- def: auto rec absence beta globulin chains on chr 11
- symp:
major: 1st year life w failure thrive + hepatosplen + microcytic anaemia, inc hba2 + hbf, hA absent
trait: hypochromic microcytic anaemia, assymp - mx:
major: repeated transfusions + desferrioxamine as high iron overload likely
b12 deficiency
- absorption
- causes
- symptoms
- mx
- absorption: needed for rbc dev. absorbed by IF which is secreted by parietal cells. then absorbed in terminal ileum
- causes: pernicious anaemia, crohns, gastrectomy, poor diet
- symptoms: macrocytic anaemia, sore tongue (glossitis), subacute degen sc, mood disturbances
- mx: IM hydroxycobalamin then treat folic acid deficiency after is present
Conditions where inc risk thrombosis
- factor lv leiden (activated protein c resistance) - thrombophilia
- prothrombin gene mutation
- antithrombin 3 def
- protein s def
- protein c def
Antiphospholipid syndrome:
- def
- complications
- mx
- def: inc risk thrombosis
- complic: recurrent miscarriage, iugr, pre-ec, placental abruption, preterm, vte
- mx: aspirin as soon as preg confirmed + lmwh once fetal heart seen in uss
Warm hemolytic anaemia
- definition
- causes
- mx
Cold:
- def
- causes
- definition: igG ab causes hemolysis at body temp and at extravasc sites such as spleen
- causes: idiopathic, autoimmune SLE, lymphoma, CLL, methyldopa
- mx: treat cause, steroids, rituximab
- definition: igM at 4C - more intravasc so raynauds, acrocyanosis etc so needs steroids
- causes: lymphoma, mycoplasma, ebv
Autoimmune hemolytic anaemia:
- ix
- reticulocytosis, low heptoglobin, inc LDH, inc bilirubin, film (spherocytes + reticulocytes), + coombs test
- types:
acquired:
paroxysmal nocturnal hemoglobinuria: PIGA gene where inc complement cascade - hemo anaemia, pancytopenia, thrombosis, hemoglobinuria. Needs Hams test: acid induced hemolysis. Needs anticoags, eculizumab, hsct
hered:
1. spherocytosis: auto dom - failure thrive, neon jaundice, splenomeg, aplastic crisis, fx. Spherocytes, inc mchc
2. g6pd def: x linked recessive where reduced nadph hence rbc suscept to oxidative stress. Neon jaudnice, hemolysis, gallstones, splenomeg. Heinz bodies. needs assay 3 months after hemolysis episode. Hemolysis when primaquine, ciprofloxacin, sulfate drugs, fava beans
3. scd
4. thalassemia
vwf disease:
- def
- ix
- mx
- def: most common inherited bleeding disorder auto dom behaves like platelet disorder so lots mucosal mem bleeding
- ix: inc bleeding time, inc aptt, factor 8 reduced
- mx: tranexamic acid if mild bleeding, desmopressin , factor 8 concentrate
Normocytic anaemia causes
anaemia chronic disease
ckd
aplastic anaemia
hemolytic anaemia
acute blood loss
Haemophilias:
- def
- symp
- ix
- def: x linked recessive 8 + 9
- symp: haemoarthroses, haematomas, prolonged bleeding
- ix: inc aptt, inc inr, inc thrombin time, inc pr time, bleeding time normal
Liver disease
- def: def 7-11, fibrinogen
- clotting: inc inr, inc aptt, fibrinogen dec, platelets dec
