Vitamin B12 and Folate Deficiency

Question 1

What are the causes/risk factors of vitamin b12 deficiency?

Answer 1

• age >65 years
• history of gastric surgery (gastrectomy, or bypass for obesity)
• vegan and vegetarian diet
• chronic gastrointestinal illnesses (e.g., Crohn’s disease or coeliac disease)
• use of known causative medications (proton-pump inhibitors, H2 receptor antagonists, metformin, anticonvulsants)

Question 2

What are the causes/risk factors of folate deficiency?

Answer 2

• low dietary folate intake
• age >65 years
• alcoholism
• pregnancy or lactation; prematurity
• intestinal malabsorption disorders
• use of trimethoprim, methotrexate, anticonvulsants, sulfasalazine, or pyrimethamine
• infantile intake of goats’ milk; and congenital defects in folate absorption and metabolism

Question 3

What are the signs and symptoms of vitamin b12 deficiency?

Answer 3

• paraesthesias
• chronic gastrointestinal disease (e.g., Crohn’s disease or coeliac disease)
• medicine (proton-pump inhibitors, H2 receptor antagonists, metformin, anticonvulsants)
• ataxia
• decreased vibration sense
• positive Romberg’s test
• pallor
• petechiae
• glossitis
• angular cheilitis
• cognitive impairment

Question 4

What are the signs and symptoms of folate deficiency?

Answer 4

• prolonged diarrhoea
• headache
• loss of appetite and weight loss
• fatigue
• shortness of breath
• dizziness
• pallor
• tachycardia
• tachypnoea
• heart murmur
• signs of heart failure
• signs of chronic alcohol abuse
• signs of haemolytic anaemia
• signs of exfoliative dermatitis
• painful swallowing
• petechiae
• glossitis
• angular stomatitis
• neurological deficits in children

Question 5

What investigations are carried out for vitamin b12 deficiency?

Answer 5

• FBC - elevated MCV, low haematocrit
• peripheral blood smear - megalocytes, hypersegmented polymorphonucleated cells
• serum vitamin B12
• reticulocyte count - low corrected reticulocyte index
• methylmalonic acid (MMA) - elevated
• homocysteine - elevated
• holotranscobalamin
• intrinsic factor (IF) antibody - positive if PA is the cause
• antiparietal cell (APC) antibody - positive result may suggest PA
• serum gastrin (fasting) - elevated if pernicious anaemia is the cause
• Schilling test

Question 6

What investigations are carried out for folate deficiency?

Answer 6

• peripheral blood smear - macrocytosis, anisocytosis, poikilocytosis, hypersegmented neutrophils
• FBC - low haemoglobin, elevated MCV and MCH; increased MCV and MCH may be absent or less than expected in combined folate and iron deficiency; thrombocytopenia, neutropenia
• reticulocyte count - low corrected reticulocyte count
• serum folate - low
• RBC folate - low
• serum vitamin B12 - normal
• serum lactate dehydrogenase (LDH) - elevated
• serum unconjugated bilirubin - elevated
• serum iron panel - elevated serum iron, ferritin, transferrin
• plasma or serum methylmalonic acid - normal
• plasma homocysteine - elevated
• bone marrow aspirate/biopsy - megaloblastic changes, erythroid hyperplasia, abnormal nuclear appearance