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| 4406888674 | What is the structure of B12? | Corrinoid ring (made of 4 pyrrole rings) | 0 | |
| 4406890722 | What does B12 convert homocysteine to? | Removes and keeps a methyl group converting it to methionine | 1 | |
| 4406891975 | What is B12 involved in? | DNA synthesis Neurotransmitter regulation | 2 | |
| 4406892857 | What are the dietary sources of B12? | - Made by bacteria; found in cow products, meat, shellfish, eggs, milk - Added to fortified grain products (cereals) | 3 | |
| 4406894473 | What is the RDI of B12? | 2.4 ug/day | 4 | |
| 4406894836 | Why is the RDI for B12 so low? | The body is very good at conserving B12 and it is stored in the liver | 5 | |
| 4406895641 | What is the first step for the absorption of B12? | - Foods containing B12 enter the stomach - In the fundus HCl and pepsin break up proteins to release food trapped cobalamin - Hepatoccrin complexes with B12 and travels to the duodenum | 6 | |
| 4406899003 | What occurs in the duodenum during B12 absorption? | Pancreatic proteases degrade HC.Cbl and releases B12 B12 then binds to IF to be absorbed | 7 | |
| 4406900667 | What occurs in the terminal ileum during B12 absorption? | IF.Cbl is absorbed in the terminal ileum via the brush border - IF receptors on enterocytes - Inside the enterocytes Cbl. is released from IF | 8 | |
| 4406903223 | What is Cbl converted to and used for in enterocytes? | - 20% converted to holotranscobalamin (TC.Cbl) and taken up by all cells for DNA synthesis, it has a short half life - 80% is conjucgated with hepatocorrin and transported to the liver for storage | 9 | |
| 4406907816 | How is recycled B12 used? | Released in the bile (1mg) - most is reabsorbed (associated with IF) into the enterohepatic circulation - The liver is capable of storing several years worth of B12 | 10 | |
| 4406909926 | What type of anaemia is most commonly associated with B12 deficiency? | Megaloblastic macrocytic pernicious anaemia | 11 | |
| 4406911032 | What symptom is seen with B12 but not folate deficiency? | Neuropathy - sub acute combined degeneration of spinal cord - Possible caused by a build up of SAM | 12 | |
| 4406912235 | What patients require B12 supplementation? | - Vegans - Malabsorption syndromes e..g pernicious anaemia | 13 | |
| 4406913793 | What is the normal Hb range? | 125-170 g/L | 14 | |
| 4406914351 | What is the normal MCV range? | 80-100 fL | 15 | |
| 4406915070 | What is the normal range for a platelet count? | 150-400 | 16 | |
| 4406915288 | What is the normal range for reticulocytes? | 10-100 | 17 | |
| 4406916027 | What type of cells are present in megaloblastic anaemia? | Hypersegmented neutrophils | 18 | |
| 4406916776 | How does the bone marrow usually respond to the stimulus of anaemia? | By increasing reticulocyte numbers | 19 | |
| 4406920071 | What are characteristics of macrocytic megaloblastic anaemia? | Low Hb High MCV Hypersegmented neutrophils | 20 | |
| 4406920900 | What are low reticulocyte numbers usually a sign of? | Impaired bone marrow production (erythropoiesis) | 21 | |
| 4406921914 | What are the requirements for normal erythropoiesis? | Iron Folate B12 | 22 | |
| 4406922634 | What other symptoms, besides anaemia, would B12 deficiency be associated with? | Loss of concentration Tingling in fingers | 23 | |
| 4406923097 | What are some causes of low B12? | - Diet - veg/vegans - Failure of absorption | 24 | |
| 4406924040 | What are some causes of failure of absorption of B12? | - Small intestine problems; B12 binds IF but not absorbed in SI (surgery to remove terminal ileum or antrum), Crohn's disease - Stomach problems; no IF e.g. pernicious anaemia | 25 | |
| 4406927697 | What are the requirements for the normal absorption of B12? | - Acid to release food bound cobalamin - Secretion of IF from healthy parietal cells - Normal pancreatic secretion - Normal ileal function | 26 | |
| 4406934873 | What does Shillings test measure? | The amount of oral B12 that is actually absorbed with IF | 27 | |
| 4406935857 | What is a normal amount of B12 to be excreted in a Shilling's test? | >10% of the oral dose | 28 | |
| 4406937098 | If the B12 absorption can be normalised with a dose of IF what is the likely cause? | Pernicious anaemia/gastritis If not corrected with IF the problem is with the distal ileum | 29 | |
| 4406938358 | What are some disadvantages of Shilling's test? | Time consuming, requires radio-isotopes and collection of urine Results are difficult to interpret- distinction between ileal and gastric disease is not clear cut | 30 | |
| 4406940322 | How can you look for evidence of autoimmune gastritis? | - Antibodies to parietal cells (also present in healthy individuals) - Antibodies to IF (Specific but not sensitive) - Other auto-immune diseases (thyroid) - Gastric biopsy - Low acid output with high plasma gastrin levels | 31 | |
| 4406942646 | How is B12 deficiency treated? | B12 replacement - Depleted reserves that have taken 3-5 years to run out - Need high doses to replace - 1000 ug every week for 4-6 weeks then maintenance of 1000 ug every 3 months (IM) - Monitor to response to B12 replacement | 32 | |
| 4406949467 | What symptoms should improve with B12 replacement therapy? | - Weight loss and diarrhoea improved after 1-2 months - Small bowel is actively replicating tissue that requires B12 to maintain cell turnover - Overall integrity and health of small bowel mucosa improves - normal function | 33 | |
| 4406951915 | What type of anaemia is iron deficiency associated with? | Microcytosis anaemia | 34 | |
| 4406952777 | How does a terminal ileal resection cause low B12? | Loss of specialized receptors on terminal ileum which leads to; - Failure to absorb B12 - Failure to reabsorb bile salts which cause irritation on colon (secretary diarrhoea) and impaired absorption of fat | 35 | |
| 4406955313 | What is involved in a Bilroth I distal gastrectomy? | Distal antrum and beginning of duodenum removed with ends rejoined | 36 | |
| 4406956342 | What is involved in a Bilroth II distal gastrectomy? | Distal antrum and beginning of duodenum removed. Duodenum sealed and jejunum sewed onto stomach | 37 | |
| 4406957708 | How does a partial gastrectomy cause low B12? | - Loss of gastric acid secretion - Atrophic gastritis due to bile reflux due to absence of pylorus - Failure of normal stimulation on pancreatic secretion/failure of mixing of pancreatic juice with food | 38 | |
| 4406960738 | How does Coeliac disease cause low B12? | - Loss of small bowel villi - Loss of endocrine cells that secrete secretin and cholescystokinin | 39 |
