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| 4464050796 | Other name for vitamin B12 | Cobalamin | 0 | |
| 4464051478 | B12 is a ___________ soluble vitamin | Water | 1 | |
| 4464052209 | Structure of B12 | Consists of a Corrinoid ring (4 pyrrole rings) - cobalt atom in centre | 2 | |
| 4464058848 | B12 found in the body in 2 forms | Methylcobalamin 5'-deoxyadenosylcobalamin | 3 | |
| 4464063410 | B12 and folate (methylation cycle) | In the cells folate is trapped in its inactive form To activate folate, vitamin B12 removes and keeps the methyl group, which activates vitamin B12 Both the folate co-enzyme and vitamin B12 co-enzyme are now active and available for DNA synthesis | 4 | |
| 4464067380 | Deficiencies of B12 or folate have significant impact on what? | Body's ability to produce new cells (normal cellular growth and metabolism) | 5 | |
| 4464094733 | Vitamin B12 is made by _______ | Bacteria - tend to get it through contamination of food sources (e.g. cows, cow products) | 6 | |
| 4464097257 | RDI for B12 | 2.4 μg/day Require only a small amount - good at conserving B12 (large amounts stored in liver) | 7 | |
| 4464098690 | Natural sources of B12 | Eggs Meat Poultry Shellfish Milk Milk products | 8 | |
| 4464101820 | B12 is also added to | Fortified grain products, such as cereals | 9 | |
| 4464105974 | Who is at risk of primary B12 deficiency | Vegan and strict vegetarian diets (don't consume meat or dairy products) | 10 | |
| 4464109240 | B12 deficiency in NZ | Last nutrition survey (2009) found quite high rates of B12 deficiency - particularly in women of Asian (Indian) ethnicity | 11 | |
| 4464121060 | Conservation of B12 | About 1mg daily is secreted in bile, most reabsorbed associated with IF (enterohepatic circulation) Liver stores - several years | 12 | |
| 4464122700 | Deficiency of B12 manifests as | Megaloblastic (macrocytic) anaemia Neuropathy | 13 | |
| 4464123000 | Megaloblastic (macrocytic) anaemia | Larger than normal RBCs Shape of RBCs is irregular Same blood film seen as in folate deficiency | 14 | |
| 4464129644 | Neuropathy as a result of B12 deficiency | Sub-acute combined degeneration of the spinal cord (? From build up of SAM in methylation cycle) Not seen in folate deficiency | 15 | |
| 4464133074 | Supplementation of B12 | Vegans Malabsorption syndromes (e.g. pernicious anaemia) are usually treated with intra-muscular injections | 16 | |
| 4464137997 | Low haemoglobin indicates | Anaemia | 17 | |
| 4464138769 | Elevated mean cell volume | Measures cell size Elevated = larger size | 18 | |
| 4464277445 | Reticulocytes | Immature RBCs Sometimes released into blood in response anaemia | 19 | |
| 4464277446 | What can explain shortness of breath and tiredness | Severe anaemia | 20 | |
| 4464278232 | Low reticulocytes in someone with anaemia | Implies that the bone marrow is unable to respond to the usual stimulus of anaemia | 21 | |
| 4464279213 | Requirements for normal erythropoeisis | Iron Folate B12 | 22 | |
| 4464282116 | Requirements to absorb B12 | Normal acid secretion (to release food-bound cobalamin) Normal intrinsic factor* (from healthy parietal cells - for absorption) Normal pancreatic secretion (pancreatic proteases release Cbl from haptocorrin) Normal ileal absorptive function* (absorbed through brush border receptors) * Most important factors | 23 | |
| 4464284439 | Lack of B12 - due to stomach problem | Lack of intrinsic factor due to pernicious anaemia Not enough intrinsic factor to bind to B12, which means B12 cannot be absorbed later on in the small intestine | 24 | |
| 4464295166 | Pernicious Anaemia | Autoimmune disorder with antibodies against intrinsic factor and parietal cells | 25 | |
| 4464296384 | Lack of B12 - due to small intestinal problem | B12 binds to intrinsic factor normally but is not absorbed in small intestine e.g. surgery to remove terminal ileum, Crohn's disease causing inflammation in the terminal ileum | 26 | |
| 4464299433 | Schilling test | Radioisotope test Used to determine if patient has lack of intrinsic factor Rarely used in clinical practice these days | 27 | |
| 4464302744 | Schilling test disadvantages | Time consuming Involves radioisotopes Requires collection of urine Results can be difficult to interpret - the distinction between ileal and gastric disease not clear-cut | 28 | |
| 4464304841 | Evidence of autoimmune gastritis | Antibodies to parietal cells Antibodies to intrinsic factor Evidence of autoimmune gastritis on gastric biopsies Evidence of low acid output (raised plasma gastrin) Evidence of other autoimmune disease (e.g. thyroid disease) - autoimmune diseases tend to occur together | 29 | |
| 4475329121 | Antibodies to parietal cells | Healthy people also have these Only negative test useful = no pernicious anaemia | 30 | |
| 4464305877 | Treatment of B12 deficiency needs to be _______ doses because of ________ | Depleted reserves have taken 3-5 years to "run-out" Need high doses to replace - 1000 mcg every week for 4-6 weeks then maintenance of 1000 mcg every 3 months | 31 | |
| 4464306505 | How is the treatment for B12 deficiency given? | Parenteral (intramuscular) - because of impaired absorption by the GI tract | 32 | |
| 4464306698 | Following treatment for B12 deficiency, need to... | Monitor response to B12 replacement - Check B12 levels - Increase in haemoglobin / reticulocyte response - Resolution of neurological symptoms | 33 | |
| 4464316308 | Failure to reabsorb bile salts (in distal ileal resection) | Bile salts are instead lost through the colon Irritant effect of bile salts on colon - secretory diarrhoea Impaired absorption of fat because of reduced bile salts (high faecal fat) | 34 | |
| 4475339726 | Explanation for low B12 after terminal ileal resection | Loss of specialised receptors on terminal ileum leads to: - failure to absorb B12 - failure to reabsorb bile salts | 35 | |
| 4464316309 | Other causes of low B12 | Coeliac disease Terminal ileal disease e.g. Crohn's Bacterial overgrowth - B12 and B12/intrinsic factor complex utilised by intestinal bacteria Chronic pancreatitis Total gastrectomy - also weight-loss procedures Some drugs - omeprazole, metformin | 36 | |
| 4475351801 | Partial gastrectomy | Billroth 1 - distal antrum and beginning of duodenum removed, 2 ends joined Billroth 2 - distal antrum and beginning of duodenum removed, duodenum closed, jejunum joined to stomach | 37 | |
| 4475358471 | Explanation for low B12 after partial gastrectomy | No antrum > no G cells > low gastrin Loss of gastric acid secretion (release of food-bound B12) Atrophic gastritis (caused by bile reflux, due to no pylorus) > loss of parietal cells > loss of IF secretion Failure of normal stimulation of pancreatic secretion/failure of mixing of pancreatic juice with food | 38 | |
| 4475369141 | Explanation for low B12 in coeliac disease | Loss of small bowel villi - mainly jejunal; some loss of ileal function Loss of endocrine cells that secrete secretin and cholecystokinin - stimulate pancreatic secretion In severe cases - damage to villi occurs from duodenum to ileum - less ileal receptors | 39 |
