B12 deficiency and pernicious anaemia Flashcards

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