7. Thyroid disease- Hypothyroidism and Goitre

Question 1

what are hypothyroidism

Answer 1

term used to describe inadequate output of thyroid hormones by the thyroid gland

Question 2

what is the most common cause of hypothyroidism

1. in the developed world
2. in the developing world

Answer 2

1. Hashimoto’s thyroiditis

2. iodine deficiency

Question 3

what is Hashimoto’s thyroiditis caused by

Answer 3

• autoimmune inflammation of the thyroid gland
• associated with antithyroid peroxidase (anti-TPO) antibodies and antithyroglobulin antibodies
• initially it causes a goitre after which there is atrophy of the gland

Question 4

What are other causes of hypothyroidism

Answer 4

Hashimoto’s thyroiditis
iodine deficiency
all of the treatments for hyperthyroidism

Question 5

name the common drugs that have the potential to cause hypothyroidism

Answer 5

carbimazole
Propylthiouracil 
radioactive iodine 
thyroid surgery 
lithium 
amiodarone

Question 6

what are the central causes of (secondary hypothyroidism) and why is it caused

Answer 6

pituitary gland fails to produce enough TSH

• associated with lack of other pituitary hormones such as ACTH
• tumours
• infection
• vascular
• radiation

Question 7

what are the common symptoms of hypothyroidism

Answer 7

Cold intolerance
hoarse/deep voice
constipation
myalgia and muscle weakness

Weight gain 
fatigue/ lethargy 
dry skin 
coarse hair and hair loss 
fluid retentions (oedema, pleural effusion, ascites) 
heavy or irregular periods

Question 8

What would primary hypothyroidism investigations show

1. site of pathology
2. TSH
3. T3 and T4

Answer 8

1. Thyroid glad
2. high
3. low

Question 9

what would secondary hypothyroidism investigations show

1. site of pathology
2. TSH
3. T3 and T4

Answer 9

1. pituitary gland
2. Low
3. Low

Question 10

What is the treatment for hypothyroidism

Answer 10

oral levothyroxine (synthetic T4)

• dose is titrated till normal TSH levels are normal
• if TSH levels are high then the dose is too low and needs to be increased
• if TSH is too low then the dose is too high and needs to be reduced

Question 11

What is the normal formulation of thyroxine, how often is it given and what are the side effects

Answer 11

mostly 100-125 mcg per day
once daily
no side effects
monitor dose with TFT

Question 12

why do you use T4 and not T3

Answer 12

T4 is produced 100 mcg a day

T3 is produced 30 mcg but 80% of this is made from T4-T3 conversion and only 20% is from thyroidal production

Question 13

what can overdosing of thyroxine cause

Answer 13

AF or osteoporosis

Question 14

If the patient still has symptoms of hypothyroidism then the dose should be increased by what increments

Answer 14

25 mcg steps

Question 15

what kind of patients should be prescribed thyroxine at low dose of 25mcg and increased slowly every 4 week and why

Answer 15

elderly patients and those with known ischaemic heart disease
higher dose may worsen angina or precipitate myocardial infarction

Question 16

which carcinoma of the thyroid is an inherited condition and is associated with adrenal tumour and hyperparathyroidism

Answer 16

medullary cell carcinoma

Question 17

What are the other red flag symptoms if someone was to present with a lump in the throat

Answer 17

dysphagia 
neck pain 
hoarseness 
history of radiation to neck 
family history of thyroid cancer

Question 18

how would you investigate a palpable goitre

Answer 18

carry out an ultrasound followed by a fine needle aspiration (FNA) of the lump

Question 19

what are the most common types of thyroid carcinomas (cancer arising in the epithelial tissue of the skin or in the lining of internal organs)

Answer 19

o	Papillary carcinoma 70%  
o	Follicular carcinoma 20%
o	Anaplastic carcinoma 3%
o	Lymphoma 2%
o	Medullary cell carcinoma 5%

Question 20

Where do medullary cell carcinomas usually arise from

Answer 20

the C cells in the thyroid

Question 21

how do you usually treat thyroid cancer

Answer 21

with surgery (total thyroidectomy or lobectomy) 
post-operative radioactive iodine treatment (selected treatment) 
thyroid hormone suppression (to suppress TSH so that tumour growth is not stimulated

Question 22

what is a goitre

Answer 22

simply means an enlarged thyroid

Question 23

what diseases can cause a diffuse goitre

Answer 23

o Graves diseases
o Hypothyroidism (hashimoto)
o Colloid goitre (euthyroid)
o Iodine deficiency drugs (lithium etc)

Question 24

are thyroid nodules common with age

Answer 24

yes they are

o 30-60% of normal thyroids have nodules at autopsy