Introduction To The Thyroid Gland

Question 1

What happens to free iodine in the body?

Answer 1

Taken up by the thyroid to form thyroid hormones is T4. Converted to T3

Question 2

What is secreted alongside T4/T3?

Answer 2

Thyroid binding globulin.

Question 3

How are the pituitary and hypothalamus involved?

Answer 3

T3 has a feedback loop via TSH back to pituitary. Also feedback loop to hypothalamus via thyroid releasing hormone.

Question 4

Why do we only measure free hormones?

Answer 4

Because only the free hormones have a metabolic effect.

Question 5

What happens to levels of hormones in pregnancy?

Answer 5

Albumin goes up and free T4 normal (total T4 increases)

Question 6

What is the most important test to carry out?

Answer 6

TSH. If normal then no thyroid disease.

Question 7

Thyroid: Generalities

Answer 7

1. Main secretory hormone is T4
2. T3 more potent
3. Free hormones only active FT4, FT3
4. TSH is best diagnostic test for DX
5. Thyroglobulin
6. Antimicrosomal ABs

Question 8

Thyroid: Generalities contd

Answer 8

Total T4 or T3 levels not always accurate:

1. Increased TBG levels:
   - Pregnancy
   - Oral contraception
2. Decreased TBG levels:
   - Nephrotic syndrome
   - Liver disease

Question 9

What is the diagnosis?

TSH(down) T4(up) T3 (up) RAIU (up)

Answer 9

Primary Hyperthyroidism
Diffuse uptake in thyroid then graves disease
On or two solitary uptakes then toxic nodular goitre

Question 10

What is the diagnosis?

TSH (down) T4 (up) T3 (up) RAIU (down)

Answer 10

Noticed that patient didn’t have regular hyper thyroidism symptoms
Thyroid was sensitive to touch.
Patient has sub acute thyroiditis