Laboratory Medicine

Question 1

What is primary hypothyroidism?

Answer 1

Problem with the thyroid gland itself

Question 2

What is secondary hypothyroidism?

Answer 2

Malfunction of the pituitary gland or hypothalamus

Question 3

What are the autoimmune causes of primary hypothyroidism?

Answer 3

• Autoimmune thyroiditis
• Hashimoto’s thyroiditis: = (Autoimmune
  thyroiditis + goitre)

Question 4

What are the iatrogenic causes of primary hypothyroidism?

Answer 4

• Previous Rx : Radioiodine ablation
• Thyroidectomy
• Antithyroid drugs: e.g. propylthiouricil

Question 5

What are the transient causes of primary hypothyroidism?

Answer 5

• Viral subacute thyroiditis

- Postpartum thyroiditis

Question 6

What are the other causes of primary hypothyroidism?

Answer 6

• Medications: amiodarone, lithium, propranolol, prednisolone, hydrocortisone
• Idiopathic
• Iodine deficiency (rare in West)

Question 7

What are the congenital causes of primary hypothyroidism?

Answer 7

• Agenesis /dysgenesis

- Defects in thyroid hormone synthesis

Question 8

What is the most common neurological manifestation of vitamin B12 deficiency?

Answer 8

Subacute combined degeneration (SCD) of the spinal cord

Usually secondary to autoimmune gastritis

Question 9

What is believed to cause myelin toxicity?

Answer 9

Accumulated methylmalonic acid

Question 10

What is essential thrombocythaemia?

Answer 10

• Chronic myeloproliferative disorder

- Excess number of megakaryocytes and platelets

Question 11

What are other chronic myeloproliferative disorders?

Answer 11

• Polycythaemia vera: excess number of erythrocytes
• Chronic myeloid leukaemia: unregulated growth of myeloid cells
• Primary myelofibrosis: marrow is replaces with fibrous scar tissue

Question 12

What are the molecular mutations used to test for myeloproliferative disorders?

Answer 12

• JAK2 mutation **
• Cal-reticulin mutation
• MPL mutation

Question 13

What is JAK2 involved with? What occurs if its mutated?

Answer 13

JAK2 gene codes for a protein that is involved in signalling

Mutations in this gene seem to make haematopoetic cells more sensitive to hormones that stimulate erythrocyte and platelet production