Oxford Clinical Medicine II

Question 1

What is the protein that thyroxine and triiodothyronine usually bound to?

Answer 1

TBG Thyroxine-binding globulin

Question 2

Which is more useful and why: free T3 and T4 levels or total T3 and T4 levels?

Answer 2

Free T3 and T4 levels. This is because total T3 and T4 levels can be influenced by TBG. Total T3 and T4 increase with increasing TBG, and vice versa.

Question 3

Which condition will increase levels of TBG?

Answer 3

TBG is increased in pregnancy, oestrogen therapy such as HRT or oral contraceptives, and hepatitis.

Question 4

Which condition will cause TBG levels to decrease?

Answer 4

TBG is decreased in nephrotic syndrome and malnutrition (both from protein loss), drugs (androgens, corticosteroids, phenytoin), chronic liver disease and acromegaly.

Question 5

Is Graves disease more prevalent in females or males?

Answer 5

More prevalent in females

Question 6

What are the signs of thyrotoxicosis?

Answer 6

Weight loss despite increased appetite.
Diarrhoea.
sweat, heat intolerance.
Palpitations and tremor.
Irritability
Exophthalmos and/or proptosis

Question 7

What is the difference between proptosis and exophthalmos?

Answer 7

Proptosis is the protrusion of eyes beyond the orbit

Exophthalmos is the appearance of a protruding eye

Question 8

What is the effect of Levothyroxine on T3, T4 and thyroglobulin levels?

Answer 8

Levothyroxine causes increased T4, decreased T3 and decreased thyroglobulin.

Question 9

What are the medications given to manage thyrotoxicosis?

Answer 9

Beta-blockers such as propanolol 40MG QDS for rapid control of symtoms
Anti-thyroid medications:
1. Titration: Carbimazole 20-40MG OD PO for 4/52 and reduce to 5-15MG according to TFTs every 1-2 months.
2. Block-replace: Give Carbimazole and thyroxine simultanoeusly
3. Propylthiouracil 200-400MG daily in divided doses TDS, and then reduced to 50-150MG daily in divided doses TDS.

Question 10

What is the chief cause of primary hypothyroidism?

Answer 10

iodine deficiency is the chief cause of primary hypothyroidism

Question 11

What is Amiodarone?

Answer 11

Amiodarone is an iodine-rich drug structurally like T4.

Hypothyroidism can be caused by toxicity from iodine excess, as T4 release is inhibited.

Question 12

What are the causes of hypothyroidism?

Answer 12

1. Iodine deficiency
2. Post-thyroidectomy or radioiodine treatment
3. Drug induced, such as anti-thyroid drugs, amiodarone, lithium, iodine
4. Subacute thyroiditis: Temporary hypothyroidism after hyperthyroid phase

Question 13

When is parathyroid hormone secreted?

Answer 13

PTH is secreted in response to low ionised Ca2+ levels

Question 14

What are the 3 possible causes of hyperparathyroidism?

Answer 14

80% is from solitary adenoma, 20% from hyperplasia of all glands and <0.5% is from parathyroid cancer

Question 15

What must be checked for every patient with hypertension?

Answer 15

Always check Ca2+ levels in patients with hypertension, as hyperparathyroidism can cause an increase in BP

Question 16

What are the presentations of hyperparathyroidism?

Answer 16

1. Fatigue, depressed, thirsty, dehydrated but polyuric, renal stones, abdominal pain, pancreatitis, duodenal ulcers/gastric ulcers(less common)
2. Bone resorption leads to pain, fractures, osteopenia/osteoporosis
3. Increased BP

Question 17

What are the tests results for hyperparathyroidism?

Answer 17

Increased Ca2+ and PTH, with decrease in phosphate (unless in renal failure)

Question 18

What is the action of Cinacelcet?

Answer 18

Cinacalcet increases the sensitivity of parathyroid hormones to calcium, and thus decrease the secretion of PTH

Question 19

What can chronic renal failure and decrease VitD intake result in?

Answer 19

Secondary hyperparathyroidism: Low Ca2+ and high PTH

Question 20

What are the causes of secondary hyperparathyroidism?

Answer 20

Decreased vitamin D intake or chronic renal failure

Question 21

What does hyperpigmentation in skin folds indicate?

Answer 21

Addison’s disease

Question 22

How does Propylthiouracil works?

Answer 22

Propylthiouracil decreases the amount of thyroid hormone produced by the thyroid gland and inhibits the conversion of thyroxine to triiodothyronine.