Clinical Thyroid Disease

Question 1

What is the normal anatomy and physiology of the thyroid and its regulation through the hypothalamic pituitary thyroid axis?

Answer 1

1. Anatomy – Right Lobe, Left Lobe, Isthmus
2. Physiology – Hypothalamus produces TRH, TRH acts on anterior pituitary which produces TSH, TSH travels to the Thyroid gland where it produces T3 and T4 with Iodine which either comes from diet or skin.

c. The production of T3 and T4 gives a -ve feedback signal to the anterior pituitary to stop producing TSH

Question 2

What are the principles of the tests that look for over and under production of different thyroid hormones?

Answer 2

1. The test for primary hypothyroidism is looking for lowered T3/4 and raised TSH
2. The test for secondary hypothyroidism is looking for low TSH and low T3/4
3. The test for primary hyperthyroidism is looking for raised T3/4 and low TSH
4. The test for secondary hyperthyroidism is looking for high TSH and high T3/4

Question 3

What are the common methods of testing for thyroid hormone levels and methods available for thyroid imaging?

Answer 3

1. Tests for Thyroid hormone levels:
   
   1. TSH & T4 levels
   2. Autoantibodies – Thyroid Peroxidase antibodies (TPO), +ve test result in Graves disease
2. Thyroid imaging techniques:
   
   1. Ultrasound

Question 4

What are the common presentations of hyper and hypothyroidism and their associated physical signs?

Answer 4

1. Hyperthyroidism:
   
   1. Weight loss
   2. Neck swelling - Goitre
   3. Bulging eyes - Proptosis
   4. Heat intolerance
   5. Anxiety
   6. Palpitations
2. Hypothyroidism:
   
   1. Weight gain
   2. Depression & lethargy
   3. Feeling the cold
   4. Dry hair and skin
   5. Goitre
   6. Constipation

Question 5

What is the treatment of hyperthryoidism?

Answer 5

1. Antithyroid drugs (Carbimazole Propylthiouracil)
2. Radioiodine

Question 6

What is the treatment of hypothryoidism?

Answer 6

1. Levothyroxine (T4)

Question 7

What is the presentation, investigation and management of thyroid cancer?

Answer 7

1. Presentation – Papillary (local spread to lymph nodes - most common) or follicular types (metastases to lung/bone)
2. Investigation –TFT’s, USS, FNA
3. Management – Surgical, destroy the cancer with radioiodine, or put the cancer to ‘sleep’ with thyroxine

Question 8

What are the classifications of Thyroid Tumours?

Answer 8

1) Follicular Adenoma
2) Differentiated Thyroid Carcinoma:
- Papillary carcinoma (75-85%), excellent prognosis
- Follicular carcinoma (10-20%)