Macrocytic Anaemia Flashcards
Define Macrocytic Anaemia?
Anaemia associated with a high MCV of erythrocytes (> 100 fl in adults)
What are the two main types of Macrocytic Anaemia?
Megaloblastic
Non-Megaloblastic
What is Megaloblastic Macrocytic Anaemia?
When the bone marrow produces unusuually large, structurally abnormal, immature red cells
What is the aetiology of Megaloblastic Macrocytic Anaemia?
Caused by deficiency of B12 or Folate required for the conversion fo deoxyuridate to thymidylate, DNA synthesis and nuclear maturation
What are the causes of Vitamin B12 deficiency?
Reduced absorption (e.g. post-gastrectomy, pernicious anaemia, terminal ileal resection or disease) Reduced intake (vegans) Abnormal metabolism (congenital transcobalamin II deficiency)
What are the causes of Folate Deficiency?
Reduced intake (alcoholics, elderly, anorexia)
Increased demand (pregnancy, lactation, malignancy, chronic inflammation)
Reduced absorption
Jejunal disease (e.g. coeliac disease)
Drugs (e.g. phenytoin)
What drugs can cause Megaloblastic Macrocytic Anaemia?
Methotrexate (dihyrdofolate reductase inhibitor)
Hydroxyurea
Azathioprine
Zidovudine
What are the causes of Non-Megaloblastic Macrocytic Anaemia?
Alcohol excess Liver disease Myelodysplasia Multiple Myeloma Hypothyroidism Haemolysis (shift to immature red cell form - reticulocytosis) Drugs (e.g. tyrosine kinase inhibitor)
What is the epidemiology of Macrocytic Anaemia?
More common in ELDERLY FEMALES
Pernicious anaemia is the MOST COMMON cause of B12 deficiency in the West
What are the presenting symptoms of Macrocytic Anaemia?
Non-specific symptoms of anaemia
Family history of autoimmune disease
Previous GI surgery
Symptoms of the CAUSE (e.g. weight loss, diarrhoea)
What are the Non-specific symptoms of Anaemia?
Tiredness
Lethargy
Dyspnoea
What are the various groups of signs for Macrocytic Anaemia on physical examination?
Signs of Anaemia
Signs of Pernicious Anaemia
Signs of B12 deficiency
What are the Signs of Anaemia for Macrocytic Anaemia on physical examination?
Pallor
Tachycardia
Breathlessness
What are the Signs of Pernicious Anaemia for Macrocytic Anaemia?
Mild jaundice
Glossitis
Angular Stomatitis
Weight Loss
What are the signs of B12 deficiency for Macrocytic Anaemia on physical examination?
Peripheral neuropathy Ataxia Subacute combined degeneration of the spinal cord Optic atrophy Dementia
What investigations do we do for Macrocytic Anaemia?
Bloods Blood Film Schilling Test Bone Marrow Biopsy (rarely needed) Investigations for the cause
What bloods do we do for Macrocytic Anaemia?
FBC LFT ESR TFT Serum Vitamin B12 Red cell folate Anti-parietal cell and anti-intrinsic factor antibodies Serum protein electrophoresis
What do we look for on a FBC for Macrocytic Anaemia?
High MCV
Pancytopaenia in megaloblastic anaemia
Different degrees of cytopaenia in myelodysplasia
Exclude reticulocytosis
What do we look for on LFT for Macrocytic Anaemia?
High bilirubin (due to ineffective erythropoiesis or haemolysis)
What are we looking for in Serum Protein Electrophoresis for Macrocytic Anaemia?
Looking for a dense band in myeloma
What do we see on a Blood Film for Macrocytic Anaemia?
Large erythrocytes
What do we see on a Blood Film for Megaloblastic Anaemia?
Megaloblasts
Hypersegmented neutrophil nuclei
What is the Schilling Test?
Method of testing for pernicious anaemia
B12 will only be absorbed when given with intrinsic factor
What is the management plan for Pernicious Anaemia-related Macrocytic Anaemia?
IM hydroxycobalamin for life
What is the management plan for Folate Deficiency-related Macrocytic Anaemia?
Oral folic acid
If B12 deficiency is present, it must be treated before the folic acid deficiency
What are the possible complications of Macrocytic Anaemia?
Pernicious Anaemia leads to increased risk of gastric cancer
Pregnancy - folate deficiency increases the risk of neural tube defects
What is the prognosis for patients with Macrocytic Anaemia?
Majority are treatable if there are no complications
