Vitamin B12 and folate deficiency Flashcards
What is vitamin B12/ folate deficiency?
Insufficient vitamin B12/ folate to meet demands.
Where is B12 found? Where does absorption occur?
B12 is found in meat + animal protein foods
Absorption occurs in the terminal ileum + requires intrinsic factor (produced by gastric parietal cells)
What is pernicious anaemia?
AI condition involving gastritis, atrophy of all layers of the body + fundus of the stomach + loss of normal gastric glands, parietal + chief cells => lack of IF
Accounts for 80% of megaloblastic anaemia due to impaired vitamin B12 absorption
Other than pernicious anaemia, list 4 other categories of causes of b12 deficiency?
Gastric: gastrectomy, atrophic gastritis = loss of IF production
Inadequate intake (e.g. vegan): stores last 3-4yrs
Intestinal: malabsorption, ileal resection, Crohn’s
Drugs: colchicine, metformin
List 3 causes of decreased folate intake
Anorexia
Alcoholics
Elderly
List 5 causes of increased folate demand
Pregnancy/ lactation Malignancy Chronic inflammation Chronic haemolytic anaemia Haemodialysis
List 2 causes of decreased folate absorption
Jejunal disease (coeliac's/ Whipples's) SI resection
List 3 medications that can cause folate deficiency
Phenytoin (anti-epileptic)
Trimethoprim (Abx)
Sulphasalazine (DMARD)
Describe the epidemiology of B12 and folate deficiency
Peak age = 60 yrs
Vegans have a higher risk of dietary vitamin B12 deficiency
Preg: need to be on folate supplements
List 6 general anaemia symptoms caused by B12 and folate deficiency
Fatigue Lethargy Dyspnoea Faintness Palpitations Headache
List symptoms of B12 deficiency
Sx of anaemia
Neurological: Peripheral neuropathy, SCDC, Neuropsychiatric disease
Mild jaundice
Glossitis
List 3 symptoms of folate deficiency
Sx of anaemia
Diarrhoea
Headache
List 6 neurological symptoms of b12 deficiency
Peripheral neuropathy: tingling, numbness
SCDC: impaired proprioception, vibration, sensation, spasticity, ataxia
Neuropsychiatric disease: reversible dementia
Optic neuropathy
Autonomic dysfunction: impotence + incontinence
Rombergs positive
What investigations are used for B12 and folate deficiency?
NO gold standard
Measurement of serum B12/ folate is not very accurate or reliable
FBC + blood film
What is seen on blood film in B12 and folate deficiency?
Elevated MCV, low haematocrit Hypersegmented neutrophils Oval macrocytes Circulating megaloblasts Low corrected reticulocyte index
Which pernicious anaemia tests may you perform in b12 deficiency?
Anti-intrinsic factor antibodies
Anti-parietal cell antibodies
Schilling test: increased excretion of B12 with added IF (rarely used)
List 3 new tests for B12 deficiency
Plasma total homocysteine (elevated)
Plasma methylmalonic acid (elevated)
Holotranscobalamin (low)
