20. The Clinical Spectrum of Thyroid Disease

Question 1

How long has thyroxine been around for?

Answer 1

At least 480 million years.

Question 2

How does thyroxine affect amphibians?

Answer 2

Aids their metamorphosis, e.g. with a tadpole to a frog.

Question 3

How does thyroxine affect salmon?

Answer 3

Regulates salmon smoltification, adaption from freshwater to saltwater life.

Question 4

What do the following symptoms suggest?

Loss of appetite, listlessness, vomiting, diarrhoea, tachycardia, high T4 levels, low TSH levels.

Answer 4

Hyperthyroid.

Question 5

qWhat do the following symptoms suggest?

Borderline T4 levels (slightly raised), High T4 levels seven weeks later, hyperactive and increased appetite.

Answer 5

Hyperthyroid.

Question 6

Where does the thyroid originally start in human embryology?

Answer 6

It starts where the tongue is but migrates down to the throat to where it is now - wrapped around the trachea.

Question 7

Where is the thyroid found in ectopic thyroidism?

Answer 7

At the back of the tongue.

Question 8

Why are heel prick tests taken from every baby in the UK, considering thyroid function?

Answer 8

To test for hypothyroidism, in new borns, hypothyroidism causes cretinism. The heel prick tests for this and means treatment of thyroxine can be started immediately to avoid mental retardation.

Question 9

How do thyroid hormones act?

Answer 9

Directly on the cell surface.

Question 10

What are some possible causes of hypothyroid disease?

Answer 10

Autoimmune disease (key reason), post-surgery, radioactive iodine, anti-thyroid drugs, secondary (lack of TSH), congenital, iodine deficiency (Derbyshire neck story) or rare inborn errors.

Question 11

What two autoimmune disorders can cause hyperthyroidism?

Answer 11

Toxic multinodular goitre and Grave’s disease.

Question 12

What are some possible causes of hyperthyroid disease, apart from autoimmune disease?

Answer 12

Solitary toxic adenoma, excess T4 (or T3 - more dangerous) therapy, excess iodine - amiodarone, ectopic thyroid tissue.

Question 13

What are some key clinical presentations that distinguish between hypothyroidism and hyperthyroidism?

Answer 13

Hypo - hair and nail growth will be slower

Hyper - weight loss and appetite both increased.

Question 14

What is the incidence ratio between males and females for thyroid disease?

Answer 14

7:1 female:male.

Question 15

What percentage of UK women have thyroid disease?

Answer 15

1-2%.

Question 16

What do the following Free T4 and TSH level results suggest?

a. Normal T4 and normal TSH
b. Low T4 and high TSH
c. High T4 and low TSH

Answer 16

a. Euthyroid (normal)
b. Hypothyroid
c. Hyperthyroid.

Question 17

What is a thyroid storm?

Answer 17

Very extreme hyperthyroidism. Often in female patients in their 20s. Their temperature gets to 40 C, BP becomes immeasurable, HR goes up to 200 and it’s a fatal condition. There is treatment but not fool-proof and some have a stroke as a result of the treatment.

Question 18

What is a myxoedema coma?

Answer 18

Very extreme hypothyroidism. Low temperature, unresponsive to painful stimuli. Treatment shows wonderful improvement.

Question 19

What is sick euthyroid syndrome and why can it cause problems with thyroid function tests?

Answer 19

Sick in-patients in hospital commonly have low T3 levels and raised rT3, T4 and fT4 are often low too. So results from a TFT may suggest there is a problem with the thyroid when it’s actually fine.

Question 20

How could having a large goitre affect the rest of the body? Use a case study to illustrate your point.

Answer 20

There was an old lady who had a very large goitre. Goitres have increased blood flow to the area, which gave this patient heart failure due to lack of blood going to the heart and elsewhere. Her thyroid was removed and her heart failure also went!

Question 21

Why might a patent resist treatment for thyroid disease?

Answer 21

Because it is a life long condition so has a stigma attached, this means the patient may want to deny having the condition.