7 - Thyroid disease

Question 1

What to incude in a history of Thyroid disease?

Answer 1

Unintentional wieght loss

Tierdness

GI - anorexia, abdo pain, IBD symptoms

Depression

Eating disorder

polyuria and poly dipsia - exclude T1 DM

Night sweats and fever - exlcude malignancy

Question 2

What are the symptoms of hyperthyroidism?

Answer 2

Wieght loss with good apetite

Tachycardia with AF

Sweaty and hot

Frequent bowel action

Irritable

sometimes have goiter

Upper eye retraction - superior tarsus (smooth) muscle
Thyroid eye disease

Question 3

What disease is Thyroid eye disease most commonly seen?

Answer 3

Graves diseas

TSH receptors behind eye

Question 4

What features of Thyrotoxicosis on examination?

Answer 4

Tremour

Onycholysis - painless detachemnt of the nail bed

Acropachy - soft tissue swelling of hands and feet

Clubbing

Question 5

What cells produce calcitonin?

Answer 5

C cells

Calcitonin - lower serum [Ca²⁺] by inhibiting osteoclast and inhibiting reabsoption of renal Ca²⁺

Question 6

Describe the process of Thyroid hormone synthesis?

Answer 6

TSH activates TSHR to secrete colloid

sodium iodide symporter imports iodine

organification occurs where thyroid peroxidase (TPO) adds iodine to tyrosine from thyroglobulin to produce T3 and T4

Endocytose from colloid into circulation

T4 is deiodinised in peripheral tissue to become T3

T3 binds to nuclear hormone receptor leading to the transcription of DNA

Question 7

Describe the Pituituary-thyroid axis

Answer 7

Question 8

What Treatment of Thyrotoxicosis?

Answer 8

Beta-blockers - treatment of Symptoms

1^st line Carbimazole

2^nd line Propylthiouracil

Radiotherapy - I¹³¹

Thyroidectomy

Question 9

How is thyrotoxicosis managed with carbimazole?

Answer 9

Titration - start at 40mg then - 15mg.

Block replace - 40mg mainatained and replaced T4 with levothyroixine. Contraindicated in pregnancy

Question 10

What is Graves disease?

Answer 10

Auto-immune antibiodies which activate TSH-R by molecular mimicry

Common to have exopthalmos and diffuse goitre.

Most common cause of thyrotoxicosis

Question 11

What is hashimotos disease?

Answer 11

Lymphocyte infilatraiton of the thyroid gland with autoimmune antibodies for TPO and thyroglobulin.

Most common cause of hypothyroidism

Question 12

Symptoms of hypothyroidism?

Answer 12

Weightloss

Profound lethargy

cold

dry brittle hair

constipaiton and heavy periods

myeodema

Question 13

Treament of hypothyroidism?

Answer 13

Levothyroxine - start at 50mg and titrate up + 25mg

complications: AF and osteoarthritis

Question 14

What feature specific to graves disease?

Answer 14

ophthalmoplegia - weakness in extraoccular muscles

Exopthalmos

Thyroid Acropachy - soft tissue swelling of finger and feet and clubbing

Question 15

What disease cause Goitre?

Answer 15

Graves

Hashimotos

Colloid

Iodine deficiency

Lithium

Question 16

Which drugs can cause thyrotoxicosis?

Answer 16

INF

amiodarone - arrythmia medication

Question 17

Solitary nodules of the thyroid can become malignant. Which is most common?

Answer 17

Pappilary thyroid cancer

Question 18

What is the pathology of post partum hemorrhage thyroiditis?

Answer 18

A form of hashimotos where TPO attack the thyroid leading to a large release of T4. This is followed by subsequent hypothyroidism.

Has a greater ration of T4 compared to T3

Question 19

What is Sheehans syndrome?

Answer 19

The pituitary (normally anteior) becomes infarcted after post partum heamorrhage leading to 2^nd (central) hypothyroidism.

Question 20

How might a radioactive I¹³¹ scan differenciate between post partum heamorrhage thyroidititis and graves disease?

Answer 20

Radioactive scan will be greatest in graves as there is an incraesed uptake in iodine.

Question 21

How is post partum heamorrhage treated?

Answer 21

No carbimazole/propylthiouracil given.

Popanolol for symptomatic release of thyrotoxicosis.