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| 5514023854 | Vit B12 sources | Meat, fish, and dairy products but not in plants. | 0 | |
| 5514025563 | How long do Vit B12 body stores last for? | 4 years | 1 | |
| 5514026667 | What does B12 bind to in the stomach? | Intrinsic factor | 2 | |
| 5514027987 | Where is the B12-intrinsic factor complex absorbed? | The terminal ileum | 3 | |
| 5514028516 | Why is RBC production slow in B12 deficiency? | In B12 deficiency, synthesis of thymidine, and hence DNA is impaired so RBC production is slow. | 4 | |
| 5514039882 | B12 deficiency causes | - Dietary (e.g. vegans) - Malabsorption: stomach (lack of intrinsic factor): pernicious anaemia, post-gastrectomy; terminal ileum: ileal resection, Crohn's disease, bacterial overgrowth, tropical sprue, tapeworms - Congenital metabolic errors | 5 | |
| 5514045921 | Features of B12 deficiency | - Symptoms of anaemia - 'Lemon tinge' to skin due to combination of pallor and mild jaundice (due to haemolysis) - Glossitis - Angular cheilosis - Neuropsychiatric: irritability, depression, psychosis, dementia - Neurological: parasthesiae, peripheral neuropathy - Subacute combined degeneration of the spinal cord: The classic triad is extensor plants (UMN), absent knee jerks (LMN), and absent ankle jerks (LMN). It may present with falls at night time due to a combination of ataxia and reduced vision, which is also seen in reduced B12. | 6 | |
| 5514054447 | Pernicious anaemia: cause | Autoimmune atrophic gastritis, leading to achlorhydria and lack of gastric intrinsic factor secretion | 7 | |
| 5514055848 | Pernicious anaemia: incidence | 1:1000 Usually >40 years Higher incidence if blood group A | 8 | |
| 5514057643 | Pernicious anaemia: associations | Other autoimmune diseases: thyroid disease, vitiligo, Addison's disease, hypoparathyroidism. Carcinoma of stomach is 3-fold more common in pernicious anaemia so have a low threshold for upper GI endoscopy. | 9 | |
| 5514060766 | Pernicious anaemia: tests | - Reduced Hb - Increased MCV - Reduced serum B12 - Hypersegmented polymorphs - Specific tests for PA: 1. Parietal cell antibodies: found in 90% with PA; 2. Intrinsic factor (IF) antibodies: specific to pernicious anaemia but lower sensitivity. | 10 | |
| 5514066800 | Pernicious anaemia: treatment | Treat the cause if possible If a low B12 is due to malabsorption, injections are required. Replenish stores with hydroxocobalamin (B12) 1mg IM altenate days e.g. for 2 weeks. Maintenance: 1mg IM every 3 months for life. If the cause is dietary, then oral B12 can be given after the initial acute course. Initial improvement is heralded by a transient marked reticulocytosis and hence increased MCV after 4-5 days. | 11 | |
| 5514075575 | Pernicious anaemia: prognosis | Supplementation usually improves peripheral neuropathy within the first 3-6 months, but has little effect on cord signs. Patients do best if treated as soon as possible after the onset of symptoms: don't delay! | 12 | |
| 5514078363 | Non-dietary, non-autoimmune causes of a low B12 | - Crohn's and coeliac disease - After gastric surgery - Acid suppressors - Metformin - Pancreatic insufficiency - False-low reading (seen in >20% so always do 2 readings!) | 13 |
