Macrocytic Anaemia Flashcards
What is macrocytic anaemia?
Anaemia associated with a high MCV of erythrocytes (> 100 fl in adults)
What are the 2 types of macrocytic anaemia?
Megaloblastic
Non-megaloblastic
What is megaloblastic anaemia?
Bone marrow produces unusually large, structurally abnormal, immature red cells
What causes megaloblastic anaemia?
B12 or folate deficiency
Required for conversion of deoxyuridate to thymidylate, DNA synthesis + nuclear maturation
List 4 causes of B12 deficiency
Reduced intake (vegans)
Reduced absorption post-op eg, gastrectomy or ileal resection.
Reduced absorption: Pernicious anaemia.
Abnormal metabolism (congenital transcobalamin II deficiency)
List 5 causes of folate deficiency
Reduced intake (alcoholics, elderly, anorexia) Increased demand (pregnancy, malignancy) Reduced absorption Jejunal disease (e.g. coeliac) Drugs (e.g. phenytoin)
List 8 causes of non megaloblastic macrocytic anaemia
Alcohol excess Liver disease Hypothyroidism Haemolysis (reticulocytosis) Aplastic anaemia Myelodysplasia Multiple myeloma. Drugs
Give 2 facts on the epidemiology of macrocytic anaemia
More common in ELDERLY FEMALES
Pernicious anaemia= MOST COMMON cause of B12 deficiency in the West
What are 5 presenting symptoms of macrocytic anaemia?
SOBOE Fatigue. Palpitations. Exacerbation of angina. Symptoms of the CAUSE (e.g. weight loss, diarrhoea)
What 2 things in the history may be relevant in a patient with suspected macrocytic anaemia?
FH of AI disease
Previous GI surgery
List 3 signs of anaemia
Pallor.
Tachycardia
Breathlessness
List 4 signs of pernicious anaemia
Mild jaundice
Glossitis
Angular stomatitis
Weight loss
List 5 signs of B12 deficiency
Peripheral neuropathy Ataxia Subacute combined degeneration of the spinal cord Optic atrophy Dementia
List 4 features to assess on a FBC in macrocytic anaemia
High MCV
Pancytopaenia in megaloblastic anaemia
Different degrees of cytopaenia in myelodysplasia
Exclude reticulocytosis
What may be seen on an LFT in macrocytic anaemia?
High BR (due to ineffective erythropoiesis or haemolysis)
List 4 other blood tests would you perform in suspected macrocytic anaemia
Serum vitamin B12
Red cell folate
Anti-parietal cell + anti-IF antibodies
Serum protein electrophoresis: looking for a dense band in myeloma
What is seen on the blood film in Macrocytosis? What about megaloblastic anaemia?
Large erythrocytes
In megaloblastic: Megaloblasts + Hypersegmented neutrophil nuclei
What does the Schilling test identify ?
Pernicious anaemia
B12 will only be absorbed when given with IF
How is folate deficiency managed?
Oral folic acid
If B12 deficiency is present, it must be treated before the folic acid deficiency
What does pernicious anaemia increase the risk of?
Gastric cancer
What does folate deficiency in pregnancy increase the risk of?
Neural tube defects
Why must B12 deficiency be treated before folate deficiency?
Treating folate deficiency 1st may aggravate the B12 deficiency + precipitate subacute combined degeneration of the cord.
What is the approach to management of Macrocytosis?
Correcting the deficiency that has caused macrocytosis, with or without anaemia.
Treating underlying condition that led to the deficiency
What is pernicious anaemia?
AI loss of parietal cells +/or intrinsic factor, thus preventing absorption of B12
How is pernicious anaemia managed?
Hydroxycobalamin B12 injections
List 4 drugs that can cause macrocytic anaemia
Methotrexate (dihydrofolate reductase inhibitor)
Hydroxyurea
Azathioprine
Zidovudine
