Vitamin B12 & folate deficiency Flashcards
Define vitamin B12 deficiency
Having insufficient vitamin B12 to meet demands
Aetiology of vitamin B12 deficiency
2
B12 is found in meat & animal protein foods
Absorption occurs in the terminal ileum & requires intrinsic factor (produced by gastric parietal cells)
Causes of vitamin B12 deficiency
5 groups
Pernicious anaemia Gastric Inadequate intake (vegan) Intestinal Drugs
Causes of vitamin B12 deficiency - pernicious anaemia
define + 2
Autoimmune condition involving gastritis, atrophy of all layers of body & fundus of stomach & loss of normal gastric glands, parietal & chief cells
Leads to lack of intrinsic factor
Accounts for 80% megaloblastic anaemia due to impaired vitamin B12 absorption
Causes of vitamin B12 deficiency - gastric
2
Gastrectomy
Atrophic gastritis
Causes of vitamin B12 deficiency - intestinal
4
Malabsorption
Ileal resection
Crohn’s affecting the terminal ileum
Tropical sprue
Causes of vitamin B12 deficiency - drugs
2
Colchicine
Metformin
Epidemiology of vitamin B12 deficiency
age + group
Peak age 60yrs
Vegans have higher risk of dietary B12 deficiency
Presenting symptoms of vitamin B12 deficiency
8 +4
Typical anaemia symptoms Fatigue Lethargy Dyspnoea Faintness Palpitations Headache
Neurological symptoms parasthesia numbness cognitive changes visual disturbances
Signs of of vitamin B12 deficiency on physical examination
8
Pallor Heart failure (w/ severe anaemia) Glossitis Angular stomatitis Neuropsychiatric: irritability, dementia, depression Neurological subacute combined degeneration of the spinal cord peripheral neuropathy
Investigations for of vitamin B12 deficiency
5
No gold standard for diagnosis Serum B12 measurement not very accurate or reliable New tests - plasma total homocysteine, plasma methylmalonic acid, holotranscobalamin FB & blood film hypersegmented neutrophils oval macrocytes circulating megaloblasts Pernicious anaemia tests anti intrinsic factor antibodies anti parietal cell antibodies Schilling test
