Megaloblastic anaemia Flashcards
what are the causes of severe B12 deficiency?
- pernicious anaemia (most common)
- lack of B12 in the diet (veganism)
- gastrectomy
- small intestinal lesions
- nitrous oxide (can rapidly inactivate body B12)
how long does it take for the body stores of B12 to deplete at the rate of 1-2 μg/day?
2 years
what are the causes of mild vitamin B12 deficiency?
- inadequate diet (most common)
- atrophic gastritis
- proton pump inhibitors
- chronic pancreatitis
- gluten-induced enteropathy
- HIV infection
- prolonged treatment with metformin or cholestyramine
- Zollinger-Ellison syndrome
what causes pernicious anaemia?
PA is caused by an autoimmune attack on the gastric mucosa, leading to atrophy of the stomach.
what happens to the parietal cells in pernicious anaemia?
parietal cells are destroyed which results in achlorhydria and secretion of IF is absent or almost absent
note: serum gastrin levels are raised
H pylori infection may initiate autoimmune gastritis. T or F.
True
- in younger pts it presents with iron deficiency but in older pts as PA
what are the causes of folate deficiency? hint: 5
- poor dietary intake of folate
- malabsorption: tropical sprue, gluten-induced enteropathy
- excess utilisation/excess cell turnover: pregnancy, lactation, haemolytic anaemias
- excess urinary folate loss: active liver disease, congestive HF
- drugs: anticonvulsants
- mixed: alcoholism
what are the clinical features of megaloblastic anaemia? hint: 6
- symptoms or signs of anaemia
- middle jaundiced
- glossitis (beefy red tongue)
- angular cheilosis
- mild symptoms of malabsorption with weight loss
- less frequent: purpura and widespread melanin pigmentation
severe B12 deficiency can cause a progressive neuropathy affecting the peripheral sensory nerves and posterior and lateral columns. T or F.
True
- neuropathy is symmetrical and affects the lower more than upper limbs
which one will a deficiency in the mother predispose the foetus to a neural tube defect: Folate or B12?
trick question, both will predispose the foetus to a NTD
what are some other tissue abnormalities seen with severe B12 or folate deficiency?
what are the lab findings seen in megaloblastic anaemia? hint: 8
- MCV > 98 fL
- macrocytes are oval
- reticulocyte count is low
- white cell and platelet count may be reduced
- some neutrophils show hypersegmented nuclei (with 6 or more lobes)
- bone marrow is usually hypercellular; may be megaloblastic or normoblastic
- giant and abnormally shaped metamyelocytes are characteristic
- serum uncojugated bilirubin and LDH are raised
how you diagnose vitamin B12 or folate deficiency?
It is usual to assay serum B12 and folate and in many laboratories also red blood cell folate
what happens to the serum B12, serum folate and RBC folate in B12 deficiency?
Serum B12 is low in megaloblastic anaemia or neuropathy caused by B12 deficiency. And the serum folate is normal or high and the red cell folate is normal or low.
what happens to the serum B12, serum folate and RBC folate in folate deficiency?
Serum and red cell folate are both low in megaloblastic anaemia caused by folate deficiency. B12 may be normal or borderline low.
