Vitamin B12 and folate deficiency

Question 1

What is vitamin B12/ folate deficiency?

Answer 1

Insufficient vitamin B12/ folate to meet demands.

Question 2

Where is B12 found? Where does absorption occur?

Answer 2

B12 is found in meat + animal protein foods

Absorption occurs in the terminal ileum + requires intrinsic factor (produced by gastric parietal cells)

Question 3

What is pernicious anaemia?

Answer 3

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

Question 4

Other than pernicious anaemia, list 4 other categories of causes of b12 deficiency?

Answer 4

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

Question 5

List 3 causes of decreased folate intake

Answer 5

Anorexia
Alcoholics
Elderly

Question 6

List 5 causes of increased folate demand

Answer 6

Pregnancy/ lactation  
Malignancy  
Chronic inflammation
Chronic haemolytic anaemia 
Haemodialysis

Question 7

List 2 causes of decreased folate absorption

Answer 7

Jejunal disease (coeliac's/ Whipples's) 
SI resection

Question 8

List 3 medications that can cause folate deficiency

Answer 8

Phenytoin (anti-epileptic)
Trimethoprim (Abx)
Sulphasalazine (DMARD)

Question 9

Describe the epidemiology of B12 and folate deficiency

Answer 9

Peak age = 60 yrs
Vegans have a higher risk of dietary vitamin B12 deficiency
Preg: need to be on folate supplements

Question 10

List 6 general anaemia symptoms caused by B12 and folate deficiency

Answer 10

Fatigue  
Lethargy 
Dyspnoea  
Faintness  
Palpitations  
Headache

Question 11

List symptoms of B12 deficiency

Answer 11

Sx of anaemia
Neurological: Peripheral neuropathy, SCDC, Neuropsychiatric disease
Mild jaundice
Glossitis

Question 12

List 3 symptoms of folate deficiency

Answer 12

Sx of anaemia
Diarrhoea
Headache

Question 13

List 6 neurological symptoms of b12 deficiency

Answer 13

Peripheral neuropathy: tingling, numbness
SCDC: impaired proprioception, vibration, sensation, spasticity, ataxia
Neuropsychiatric disease: reversible dementia
Optic neuropathy
Autonomic dysfunction: impotence + incontinence
Rombergs positive

Question 14

What investigations are used for B12 and folate deficiency?

Answer 14

NO gold standard
Measurement of serum B12/ folate is not very accurate or reliable
FBC + blood film

Question 15

What is seen on blood film in B12 and folate deficiency?

Answer 15

Elevated MCV, low haematocrit 
Hypersegmented neutrophils  
Oval macrocytes  
Circulating megaloblasts  
Low corrected reticulocyte index

Question 16

Which pernicious anaemia tests may you perform in b12 deficiency?

Answer 16

Anti-intrinsic factor antibodies
Anti-parietal cell antibodies
Schilling test: increased excretion of B12 with added IF (rarely used)

Question 17

List 3 new tests for B12 deficiency

Answer 17

Plasma total homocysteine (elevated)
Plasma methylmalonic acid (elevated)
Holotranscobalamin (low)