MEH Flashcards
Splenomegaly
Causes: back pressure-portal hypertension in liver disease, over work, extramedullary haemopoiesis
Examination: Palpate in Right Iliac Fossa, feel for spleen edge moving towards hand in on inspiration, feel for splenic notch
Avoid contact sports and vigorous activity = risk of rupture
Hyposplenism
= lack of functioning splenic tissue
Causes: splenectomy, sickle cell disease, gastrointestinal diseases, autoimmune disorders
Blood film: Howell Jolly bodies
Risk of sepsis from encapsulated bacteria (Strep.pneumonia, Haemophilus influenzae, meningococcus)
Treatment: lifelong antibiotic prophylaxis
Anaemia
Signs and symptoms
Haemoglobin concentration lower than the normal range
Symptoms: shortness of breath, palpitations, headaches, claudication, angina, weakness & lethargy, confusion
Signs: pallor, tachycardia, systolic flow murmur, tachypnoea, hypotension:
Specific signs: kolionychia, angular stomatitis, glossitis, abnormal facial bone development
Megaloblastic anaemias
Interference with DNA synthesis during erythropoiesis causes development of nucleus to be retarded in relation to maturation of cytoplasm
Examples: vitamin B12/folate deficiency, drugs that interfere with DNA synthesis, erythropoiesis leukaemias where DNA synthesis is retarded
Macronormablastic erythropoiesis
Normal relationship between development of nucleus and cytoplasm is retained but erythroblastosis are larger than normal and give rise to larger red cells
Examples: liver disease, alcohol toxicity, some myelodysplastic syndromes
Stress erythropoiesis
Conditions associated with high reticulocyte count
High level of erythropoietin leads to an expanded and accerlarated erythropoiesis
Examples: recovery from blood loss due to haemorrhage, recovery from haemolytic anaemia
Folate deficiency: causes and symptoms, treatment
Cause: dietary deficiency, increased requirements, disease of duodenum and jejunum, drugs which inhibit dihydrofolate reductase, alcoholism, urinary loss of folate in liver diseases and heart failure.
Symptoms: those related to anaemia, reduced sense of taste, diarrhoea, numbness and tingling in feet and hands, muscle weakness, depression
Treatment: oral folic acid
Vitamin B12
causes: dietary deficiency, lack of intrinsic factor, diseases of the ileum, lack of transcobalamin, chemical inactivation of B12, parasitic infection, some drugs that chelate intrinsic factor
symptoms: those related to anaemia, glossitis & mouth ulcers, diarrhoea, paraesthesia, disturbed vision, irritability
Treatment:
For Pernicious anaemia: IM hydroxycobalamine for life
Other causes: oral cyanocobalamine
Subacute combined degeneration of the cord
B12/folate deficiency affecting nervous system: vitb12 associated with focal demyelination
=degeneration of posterior and lateral columns of the spinal cord
symptoms: gradual onset weakness, numbness and tingling in arms, legs & trunk which progressively worsens, changes in mental state
Iron deficiency anaemia
causes: insufficient iron in the diet, malabsorption of iron, bleeding, increased requirement, anaemia of chronic disease
At risk groups: infants, children, women of child-bearing age, geriatric age group
signs and symptoms: tiredness, pallor, reduced extercise tolerance, cardiac-angina, palpitations, development of heart failure, increased respiratory rate, pica, cold hands and feet, epithelial changes (angular cheilitis, glossy tongue with atrophy of lingual papillae, koilonychia)
treatment: dietary advice, oral iron supplements, IM iron injections, IV iron, blood transfusion
Hereditary Haemochromatosis
Autosomal recessive disease caused by mutation in HFE gene on Chr6
= mutated HFE protein can’t bind to transferrin receptor so the negative influence on iron uptake is lost as welll as negative influence on hepcidin production
=too much iron enters cells leads to organ damage
Susceptible organs to damage: liver, adrenal glands, heart, joints, pancreas
Treatment: therapeutic phlebotomy to remove excress iron
Thalassaemia
blood smear: hypochromic & microcytic red cells, anisopoikilocytosis, nucleated red blood cells, Heinz bodies
Consequences:
extramedullary haemopoiesis=splenomegaly, hepatomegaly, expansion of haemopoiesis in bone cortex, reduced O2 delivery= EPO stimulates production of more defective RBCs
iron overload= excessive absorption of dietary iron due to ineffective hamatopoiesis
reduced life expectancy
treatment: RBC transfusion, iron chelation, folic acid, immunisation, holistic care, stem cell transplant, pre-conception couselling
Beta thalassaemia disease types
Gene mutation of beta-globin gene on chr11
B0= total absence of production
B+=reduction of globin production
beta thal minor/trait: usually asymptomatic with a mild anaemia
= heterozygous with 1 normal and one abnormal gene
beta thal intermedia: severe anaemia but not enough for regular blood transfusions, resembles HbH disease
=heterogenous, mild variants of homozygous, severe variants of heterozygous, double heterozygosity
beta thal major: severe transfusion-dependent anaemia. manifests 6-9months after birth as synthesis switches form HbF (a2y2) to HbA (a2b2)
=homozygous
alpha thalassaemia and its disease types
Deletion or loss of function of one or more of the four alpha globin genes= 2 alpha globin on paternal chr16 and 2, 2 on maternal chr16
silent carrier= asymptomatic
a thal trait: minimal or no anaemia
= both genes on one chr16 or one gene on each chr16 deleted, microcytosis and hypochromia in RBCs, resembles B thal minor
haemoglobin H disease: moderately severe= tetramers of B globin (HbH) form resulting in microcytic, hypochromic anaemia with target cells and Heinz bodies, resembles b thal intermedia
hydrops fatalis: severe, usually results in intrauterine death
=all four alpha genes deleted. excess y-globin forms tetramers called Hb Bart that cannot deliver O2 to tissues
Sickle Cell Disease
autosomal recessive disease- mutation of B globin gene
=GAG to GTG at position 6 of B globin forming HbS
HbS readily gives up O2. in low O2, deoxygenated HbS forms polymers that cause red cells to form a sickle shape. Irreversibly sickled red are cells less deformable and can cause occlusion in small blood vessels.
3 types of crises: vaso-occlusive, aplastic, haemolytic
consequences: vasocclusive episode, anaemia, jaudice, splenic atrophy
