Anaemias

Question 1

commonest cause of vitamin B12 deficiency?

Answer 1

reduced absorption e.g. gastric bypass, gastric atrophy, ileal stricture.
vegan diet is another cause, as well as adult pernicious anaemia, congenital lack of IF, gastrectomy, crohn’s disease, etc.

Question 2

2 causes of non-megaloblastic macrocytic anaemias (DNA synthesis not impaired, but there is RBC macrocytosis)?

Answer 2

diamond blackfan anaemia (genetic) and liver disease

Question 3

what is a megaloblast?

Answer 3

overly large, immature RBC

Question 4

4 symptoms of anaemia (generally)

Answer 4

fatigue, pallor, glossitis, SOB

Question 5

how to tell the difference between B12 and folate deficiency

Answer 5

B12–>neurological symptoms(subacute combined degeneration of spinal cord: dementia, cerebellar ataxia, loss of vibratory/position sense, etc)
Also, B12 deficiency leads to high levels of methylmalonic acid.
folate–>no neuro symptoms, normal methylmalonic acid levels

Question 6

Diagnosis of B12/folate deficiency

Answer 6

RBC macrocytosis (high MCV), hypersegmented neutrophils on blood smear.
Bone marrow study shows megaloblasts.
High homocysteine levels(needs both B12 and folate to be converted to something else).
Normal levels of methylmalonic acid in isolated folate deficiency. High levels of methylmalonic acid in isloated B12 deficiency (this is because B12 is needed for it to be converted to something else).

Question 7

How does diamond-blackfan anaemia present?

Answer 7

at infancy with small head, cleft lip/palate, small jaw, malformed thumbs.

Question 8

describe folate absorption

Answer 8

in the duodenum/jejunum. Obtained in the diet from greens, liver and yeast.
Stores last months.

Question 9

describe vitamin B12(cobalamin) absorption

Answer 9

in the ileum following combination with intrinsic factor, produced by gastric parietal cells. Obtain in the diet from animal produce only.
Stores (in liver)last years(i.e. can be vegan then only develop vitB12 deficiency years after having started the diet).

Question 10

what are the causes of folate deficiency?

Answer 10

malabsorption(crohn's disease, coeliac disease, drugs(phenytoin, trimethoprim, sulfasalazine, methotrexate, alcohol)
increased need (due to high cell turnover): pregnancy+lactation, haematological diseases(e.g. haemolytic anaemias), inflammatory diseases(e.g. crohn's RA, psoriasis)

Question 11

treatment of B12 deficiency

Answer 11

intramuscular hydroxocobalamin injections every 3 months

Question 12

treatment of folate deficiency

Answer 12

oral folic acid daily for 4 months

Question 13

general features of haemolysis

Answer 13

mild jaundice, splenomegaly, dark urine (due to excess urobilinogen), pigment gallstones, folate deficiency(due to rapid proliferation of bone marrow)

Question 14

Lab findings in haemolytic anaemia

Answer 14

raised serum bilirubin
raised urine urobilinogen
raised faecal stercobilinogen
absent serum haeptoglobins 
reticulocytosis
bone marrow erythroid hyperplasia
microspherocytes, schistocytes
osmotic fragility
autohaemolysis

Question 15

how do you detect haemoglobinopathies?

Answer 15

Hb electrophoresis (for thalassaemia, sickle cell disease)

Question 16

what is pernicious anaemia?

Answer 16

a macrocytic anaemia due to inability to absorb B12 due to a lack of intrinsic factor due to IgA antibodies which attack the intrinsic factor or the parietal cells. Assoc. with other autoimmune diseases like myxoedema, thyroiditis, diabetes, vitiligo, adrenal atrophy, etc. If you develop this in childhood, you may have an intrinsic lack of IF: usually develops around 2 years old when stores of B12 acquired from mother in utero have been used up.

Question 17

Causes of non-megaloblastic macrocytic anaemia

Answer 17

alcohol, liver disease, myxoedema, reticulocytosis, cytotoxic drugs, aplastic anaemia, primary acquired sideroblastic anaemia, pregnancy, etc