Session 4- Introduction to anaemia & Vitamin B12 and folate metabolism Flashcards

Question

macronormoblastic erythropoiesis

Answer 1

``` • Normal relationship between development of nucleus and cytoplasm is retained but erythroblasts are larger than normal and give rise to larger red cells ```

Answer 2

``` Conditions associated with a high reticulocyte count (reticulocytes are larger than normal red cells) • High level of erythropoietin leads to an expanded and accelerated erythropoiesis ```

Answer 3

These anaemias present with a reduced RBC size that are often pale (hypochromic) Thalassaemia: Reduced/absent synthesis of a globin chain in haemoglobin → abnormal facial bone development as the bone marrow tries to ramp up haemopoiesis Anaemia of chronic disease: Reduced iron availability (covered in a few slides) Iron deficiency: insufficient iron available to meet haem synthesis requirements Lead poisoning: inhibits haem synthesis enzymes Sideroblastic anaemia: genetic defect in haem synthesis

Answer 4

These anaemias present with normal sized RBCs Acute blood loss: blood volume has been lost, but no effect on RBC structure/size Bone marrow failure (aplastic): either inherited or acquired, the bone marrow stem cells can no longer produce sufficient RBCs to meet the demands of the body. Chronic disease: Reduced iron availability Destruction (haemolytic): abnormal excess breakdown of RBCs

Answer 5

``` • Dietary deficiency (Poor diet) • Increased requirements • Pregnancy • Increased erythropoiesis e.g. haemolytic anaemia • Severe skin disease (e.g. psoriasis, exfoliative dermatitis) • Disease of the duodenum and jejunum (e.g. coeliac disease, Crohn’s disease) • Drugs which inhibit dihydrofolate reductase (e.g. Methotrexate) • Alcoholism (poor diet and damage to intestinal cells) • Urinary loss of folate in liver disease and heart failure ```

Answer 6

``` Those related to anaemia • Reduced sense of taste • Diarrhoea • Numbness and tingling in feet and hands • Muscle weakness • Depression ```

Answer 7

``` • B12 released from food proteins by proteolysis in stomach where it then binds to haptocorrin • Haptocorrin B12 complex digested by pancreatic proteases in small intestine releasing B12 which then binds intrinsic factor (produced by gastric parietal cells). • Intrinsic factor–B12 complex binds to cubam receptor which mediates uptake of complex by receptormediated endocytosis into enterocytes • After lysosomal release in enterocytes, B12 exits via basolateral membrane through MDR1 • Binds to transcobalamin in blood and transported around bloodstream ```

Answer 8

``` -Dietary deficiency (Vegan diet lacking B12 supplementation) • Lack of intrinsic factor (Pernicious anaemia) • Diseases of the ileum (Crohn’s disease, ileal resection, tropical sprue) • Lack of transcobalamin (congenital defect) • Chemical inactivation of B12 e.g. frequent use of anaesthetic gas nitrous oxide • Parasitic infestation (rare tapeworm found in fish can trap B12) • Some drugs can chelate intrinsic factor (e.g. hypercholesterolaemia drug Cholestyramine) ```

Answer 9

``` Those related to anaemia • Glossitis & mouth ulcers • Diarrhoea • Paraesthesia • Disturbed vision • Irritability ```

Answer 10

degeneration of posterior and lateral columns of the spinal cord ``` • Gradual onset weakness, numbness & tingling in arms, legs & trunk which progressively worsens. • Changes in mental state ```

Answer 11

``` • Folate deficiency in pregnancy can cause neural tube defects • Vitamin B12 deficiency associated with focal demyelination ```

Answer 12

• Vitamin B12 and folate are both necessary for nuclear division and maturation. • When B12 and folate are deficient, nuclear maturation and cell divisions lag behind cytoplasm development. • Leads to large red cell precursors with inappropriately large nuclei and open chromatin. The mature red cells are also large leading to a macrocytic anaemia

Answer 13

variance in size and shape

Answer 14

For Pernicious anaemia: Hydroxycobalamine intramuscular (NOT oral) for life For other causes of B12 deficiency: oral cyanocobalamine

Answer 15

glycated haemoglobin which is when Hb is linked to a sugar

Answer 16

excess haemoglobin in the blood. If the normal reticuloendothelial pathway for removal of red blood cells is overwhelmed or haemolysis is very severe (e.g. due to incompatible blood transfusion), a direct breakdown of red blood cells rusults in release of haemoglobin into the circulation

Answer 17

autoantibody test for autoimmune haemoltyic anaemia

Answer 18

autoantibodies interfering with the production or function of intrinsic factor Intrinsic factor is essential for the absorption of vitamin B12 in the ileum. Without intrinsic factor, vitamin B12 deficiency will occur and production of red blood cells will be impaired causing anaemia. "Pernicious” means “deadly”. Pernicious anemia was often fatal in the past before vitamin B12 treatments were available.