vitamin B12 deficiency

Question 1

define vitamin B12 deficiency?

Answer 1

● Having insufficient vitamin B12 to meet demands.

Question 2

how is vitamin B12 absorbed into the body?

Answer 2

o B12 is found in meat and animal protein foods
o Intrinsic factor is secreted from the parietal cells in the stomach
o B12 is absorbed after binding to intrinsic factor and actively absorbed into the terminal ileum.

Question 3

what are the causes of B12 deficiency?

Answer 3

o	Pernicious anaemia 
o	Post gastrectomy
o	Inadequate intake 
o	Intestinal 
-	Malabsorption
-	 ileal resection
-	 Crohn's affecting the terminal ileum
-	 tropical sprue
o	Drugs - colchicine, metformin

Question 4

what is the epidemiology of vitamin B12 deficiency?

Answer 4

● Peak age = 60 yrs

● Vegans have a higher risk

Question 5

what are the presenting symptoms of vitamin B12 deficiency?

Answer 5

●	Typical anaemia symptoms 
●	Fatigue 
●	Lethargy
●	Dyspnoea 
●	Faintness 
●	Palpitations 
●	Headache 

PLUS 
Neurological Symptoms
o	Paraesthesia 
o	Numbness 
o	Cognitive changes 
o	Visual disturbances

Question 6

what are the signs of vitamin B12 deficiency on physical examination?

Answer 6

● Pallor
● Glossitis !
● Angular stomatitis !

● Neuropsychiatric:
o Irritability
o Dementia
o depression

● Neurological
o Peripheral neuropathy
o Joint, positional and vibration sense

Question 7

gold standard investigation for Vitamin B12 deficiency?

Answer 7

● There is NO gold standard

● Measurement of serum B12 is not very accurate or reliable

Question 8

what might the blood film show?

Answer 8

o MACROCYTIC anaemia
o Hypersegmented neutrophils
o Oval macrocytes
o Circulating megaloblasts

Question 9

which tests are used for assessing presence of pernicious anaemia?

Answer 9

o Anti-intrinsic factor antibodies
o Anti-parietal cell antibodies
o Schilling test