VITAMIN B12 DEFICIENCY Flashcards
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| 4475993344 | Structure B12 | Corrinoid Ring: 4 pyrrole rings Large cobalt atom in centre | 0 | |
| 4475997202 | How do B12 and folate work together? | Methylation cycle. To activate folate: B12 removes and keeps methyl group, which activates B12; methyl cobalamin Both the folate co-enzyme and B12 co-enzyme are available and active for DNA production | 1 | |
| 4476012403 | Recycling of homocysteine? | Homocysteine recycling into Methionine is important and needs the donation of the methyl group from folate to B12 in order for homocysteine to convert to Methionine | 2 | |
| 4476022882 | Both deficiency of B12 and folate have serious impact on? | Co-enzymes = DNA production Deficiency = inability to produce new cells; RBC (high turnover) | 3 | |
| 4476025793 | Dietary sources of B12 | Naturally from animal sources only that are protein rich: egg, poultry, meat, shellfish, milk and milk products Also fortified grain products eg) cereals, breads | 4 | |
| 4476031358 | Storage of B12 | In liver, very good storage 3-5 years | 5 | |
| 4476033064 | RDI of B12 | 2.4 micrograms per day (due to high storage) | 6 | |
| 4476034462 | People at risk of B12 deficiency + why? | Vegans + vegetarians as most B12 from animal sources (need supplements) | 7 | |
| 4476038845 | Stages of B12 absorption in brief. | 1. Cbl.P enters stomach. HCl (parietal), Pepsin (chief) cleave protein from Cbl 2. Cbl binds to R-binder protein : haptocorrin --> Hc.Cbl 3. Travels to duoendum. Pancreatic proteases seperate Hc.Cbl, at same time intrinsic factor released (parietal), binds to cobalimin; IF. Cbl. 4. IF.Cbl travels to terminal ileum: brush border receptors for IF. IF.Cbl --> enterocyte. IF seperated from Cbl 5. 20% of Cbl forms holotranscobalimin; goes to cells for DNA production, especially RBC, gut enterocytes (high turnover) 6. 80% forms Hc.Cbl --> travels to liver for storage. Stored for 3-5 years. | 8 | |
| 4476066725 | Recycling of B12? | Lose B12 through bile -> Small intestine --> back to liver through enterohepatic circulation | 9 | |
| 4476072422 | Common characteristic of B12 and folate deficiency? | MACROCYTIC ANAEMIA -large red blood cells and abnormal/irregular shape -due to decline in DNA --> RBC production | 10 | |
| 4476079589 | IDENTIFYING CHARACTERISTIC OF B12 DEFICIENCY | Sub-acute combined degeneration of spinal cord, affects brain + periphery. Tingling fingers, neurological problems. Not seen in folate deficiency. possible due to build up of SAM. | 11 | |
| 4476088010 | PEOPLE WHO REQUIRE B12 SUPPLEMENTATION | Vegans + Vegetarians: oral supplements B12 malabsorption syndromes eg) pernicious anaemia = intramuscular injections of B12 | 12 | |
| 4476097147 | List some Clinical Manifestations seen in B12 deficiency blood counts | 1. Low hemoglobin (anaemia) 2. Elevated Mean Cell Volume 3. Low reticulocytes | 13 | |
| 4476103609 | General Clinical Manifestations of B12 deficiency ? | 1. Tingling in fingers, difficulty concentrating, neurological problems 2. Pernicious Anaemia (antibody blood test) 3. Low gastric acid secretion 4. Evidence of autoimmune gastritis (endoscopy) 5. Macrocytic Anaemia; short breath + tiredness | 14 | |
| 4476116985 | REQUIREMENTS TO ABSORB B12 | 1. Normal gastric acid secretion (HCl, pepsin) = to break B12 from food protein 2. Normal intrinsic factor (parietal cells) 3. Normal pancreatic secretion: require proteases to break Cbl from haptocorrin 4. Normal ilieal absorptive function (I.F receptors at brush border) | 15 | |
| 4476130181 | PERNICOUS ANAEMIA: PATHOLOGY | Autoimmune disease; autoantibodies formed against parietal cells and intrinsic factor. lack of intrinsic factor and parietal cells B12 can't be carried and absorbed to/at terminal ileum | 16 | |
| 4476131495 | COMMON CAUSE OF PERNICOUS ANAEMIA? | Autoimmune gastritis; antibodies formed against parietal + i.f | 17 | |
| 4476131496 | NORMAL I.F BUT SMALL INTESTINAL PROBLEM? | Surgery: terminal ileum resection Crohn's disease causing inflammation to terminal ileum | 18 | |
| 4476307695 | TEST TO DETERMINE LACK OF INTRINSIC FACTOR | Schilling Test | 19 | |
| 4476307734 | SCHILLING TEST? | Radioisotope Test. Historical. | 20 | |
| 4476317584 | TESTS OF PERNICOUS ANAEMIA + AUTOIMMUNE GASTRITIS | 1. Antibody Blood test: Parietal Cells Intrinsic Factro 2. Biopsy via endoscopy: see evidence of autoimmune gastritis (may be present, not always assoc. with pernicious anaemia) 3. Evidence of low gastric acid output due to parietal cell damage: WILL HAVE ELEVATED GASTRIN LEVELS IN BLOOD ; tries to stimulate acid secretion 4. Evidence of other autoimmune disease eg) thyroid | 21 | |
| 4476336801 | PROBLEMS WITH ANTIBODY BLOOD TESTS? | Antibody to parietal: healthy + non healthy have Antibody to IF: all with it will have perc. anaemia but some with perc anaemia don't have it at all | 22 | |
| 4476346463 | TREATMENT FOR NON MAL ABSORPTION B12 DEFICIENCY eg) vegans, poor diet | Supplements 1000mcg/week, for 4-6 weeks 1000mcg every 3 months | 23 | |
| 4476349362 | TREATMENT FOR MAL ABSORPTION B12 DEFICIENCY | Parenteral (intramuscular) injections. As absorption in GI tract = ineffective eg) pernicious anaemia, terminal ileal resection | 24 | |
| 4476360697 | MONITOR B12 REPLACEMENT? | -Check B12 Levels -Increase in hemoglobin + reticulocyte response -Resolution of neurological problems | 25 | |
| 4476365327 | EFFECTS OF DISTAL ILEAL RESECTION? | Failure to absorb B12 (no specialised IF receptors) Fail to reabsorb bile salts (diarrohea) | 26 | |
| 4476375725 | PARTIAL DISTAL GASTRECTOMY x2 | Billroth 1 operation Billroth 2 operation Remove distal antrum + proximal duodenum | 27 | |
| 4476381864 | Billroth 1 operation | 1. distal antrum + proximal duo. removed 2. Joined back end to end 3. Common bile duct and main pancreatic duct is left in position (in situ) | 28 | |
| 4476387272 | Billroth 2 operation | 1. distal antrum + proximal duodenum removed 2. Not joined. Duodenum sewn shut. 3. Common Bile Duct and Main pancreatic Duct and distal stomach --> sewn/attached to jejunum | 29 | |
| 4476399473 | WHY WOULD THERE BE A LOW B12 AFTER PARTIAL GASTRECTOMY | 1. No Antrum --> no G Cells --> no Gastrin =reduced gastric acid secretion: Cbl not released from food = reduced pancreatic secretion (stim. acinar cells) = Cbl not released from haptocorrin 2. Bile reflux from small intestine -> atrophic gastritis 3.Atrophic gastritis --> chronic inflammation --> lost of parietal cells --> low IF, low HCl | 30 | |
| 4476420033 | OTHER CAUSES OF LOW B12 | Celiac disease Terminal Ileal Disese (crohn's) Bacterial Overgrowth Chronic pancreatitis (low p. enzymes) Total gastrectomy Omeprazole, Metformin | 31 |