Causes of anaemia & thrombocytopenia

Question 1

Apart from blood loss, what are the main causes of anaemia?

Answer 1

• Haematinic deficiencies
• Secondary to chronic disease
• Haemolysis
• Alcohol, drugs, toxins
• Renal impairment (EPO)
• Primary haematological/marrow disease (aplastic, malignant, congenital, haemoglobin disorders)

Question 2

How can types of anaemia be categorized? What does this depend on?

Answer 2

• Depends on MCV
• Macrocytic: B12/folate/metabolic disorders, marrow damage, haemolysis
• Normocytic: chronic disease
• Microcytic: iron deficiency, haem disorders

Question 3

Describe iron balance in the body

Answer 3

• No excretion so recycled
• Controlled by gut mucosa
• Absorbed in duodenum
• Transported by transferrin
• Stored in ferritin/haemosiderin

Question 4

What are the main causes of iron deficiency anaemia?

Answer 4

• Blood loss (gut-ulcers,diverticulitis, PV-menstrual loss, PU, respiratory tract)
• Increased demand (growth, pregnancy)
• Reduced intake (diet, malabsorption)

Question 5

What is megaloblastic anaemia?

Answer 5

• Impaired DNA synthesis
• Big red cells, high MCV
• B12/folate deficiency
• Alcohol/drugs
• Haematological malignancy

Question 6

How do B12 & folate cause anaemia?

Answer 6

• DNA consists of purines/pyrimidine bases
• Folates required for synthesis
• B12 essential for cell folate generation
• Low folate/B12 starves DNA of bases

Question 7

How is vitamin B12 absorbed and how can a deficiency lead to anaemia?

Answer 7

• Absorbed by gastric parietal cells, intrinsic factor, receptors in terminal ilium
• Gastric problems: pernicious anaemia
• S.bowel problems: Crohn’s, diverticulosis

Question 8

How can a folic acid deficiency occur?

Answer 8

• Malnutrition
• Malabsorption
• Increased usage: pregnancy, inflammatory disorders, haemolysis
• Drugs/alcohol

Question 9

What are common features of B12 or folate deficiencies?

Answer 9

• Megaloblastic anaemia
• Mild jaundice
• Sterile
• Anorexia/weight loss
• Glossitis/angular stomatitis
• Pancytopenia if severe

Question 10

Describe pernicious anaemia

Answer 10

• Classic cause of B12 deficiency
• Parietal cells/intrinsic factor affected
• Autoimmune
• Atrophic gastritis w/achlorhydria

Question 11

What is SACDC?

Answer 11

• Subacute combined degeneration of the cord
• Cause of severe B12 deficiency
• Demyelination of dorsal & lateral columns
• Peripheral nerve damage
• Presents: dementia, unsteady walking, numbness & distal weakness, peripheral neuropathy

Question 12

What are common causes of haemolysis?

Answer 12

• Inside cell: enzyme defect, sickle cell
• Membrane: hereditary spherocytosis
• External: Antibodies, drugs, heart alves, vascular

Question 13

What are the common causes of thrombocytopenia?

Answer 13

• Drugs,alcohol,toxins
• Autoimmune diseases
• Liver disease/hypersplenism
• Pregnancy
• Infections
• Congenital conditions
• Haematological/marrow disease
• DIC

Question 14

What is the difference between ITP & TTP

Answer 14

• ITP: Immune thrombocytopenic purpura, common immune disorder,
• TTP: Thrombotic thrombocytopenia purpura, rare, suspected if thrombocytopenia w/fever, neuro signs, haemolysis