Hypothyroidism

Question 1

What is included in the thyroid gland?

Answer 1

Pyramidal lobe
Right lobe
Isthmus
Left lobe

Question 2

What are the 2 functions of the thyroid?

Answer 2

Synthesis of thyroid hormones
Secretion of calcitonin

Question 3

What are the thyroid hormones?

Answer 3

T3 + T4

Question 4

H ow does the thyroid maintain calcium + phosphate levels?

Answer 4

Through secretion of parathyroid hormone (PTH)

Question 5

What is included in hypothyroidism?
Too little

Answer 5

Primary = overt/subclinical
Secondary = pituitary-hypothalamic dysfunction
Peripheral

Question 6

What is primary overt hypothyroidism?

Answer 6

Clinically insufficient amount

Question 7

What is primary subclinical hypothyroidism?

Answer 7

Can’t produce it

Question 8

What is peripheral hypothyroidism?

Answer 8

Body not using what is there

Question 9

What is included in hyperthyroidism?
Too much

Answer 9

Thyroidal origin
Pituitary disease - most common
Extrathyroidal origin

Question 10

What are the hypothyroidism signs + symptoms?

Answer 10

Thinning hair
Goiter = abnormally enlarged thyroid gland
Slow metabolism (weight gain)
Dry skin
Jaundice = infants born with
Bradycardia

Question 11

What are the causes of hypothyroidism?

Answer 11

Autoimmune thyroiditis
Iodine deficiency
Post thyroidectomy/radioactive iodine treatment
Drug induced
Peripheral resistance to thyroid hormone
Congenital disease - eg. thyroid agenesis

Question 12

What is the diagnosis for hypothyroidism?

Answer 12

Symptoms
Thyroid function test (TFTs)
- TSH
- Free T4

Question 13

What does TFT show if primary overt hypothyroidism?

Answer 13

Levels raised + FT4 low

Question 14

What does TFT show if primary subclinical hypothyroidism?

Answer 14

TSH slightly raised
FT4 within normal range

Question 15

What does TFT show if secondary hypothyroidism?

Answer 15

TSH low
FT4 low

Question 16

What does TFT show if peripheral hypothyroidism?

Answer 16

rT3 low

Question 17

How are thyroid hormones released?

Answer 17

Thyroid releasing hormone comes from hypothalamus
Stimulates TSH release
Goes to thyroid
Thyroid releases T3 + T4

Question 18

What are the treatment aims for hypothyroidism?

Answer 18

Replace thyroid hormone
Correct TSH levels + resolved clinical symptoms

Question 19

What is 1st line for hypothyroidism?

Answer 19

Levothyroxine

Question 20

What is the usual starting dose for levothyroxine?

Answer 20

1.6mcg/kg rounded to nearest 25mcg dose

Question 21

What is the dose of levothyroxine if patient >65 or pre-existing CVD?

Answer 21

Reduced starting dose of 25-50mcg OD
= due to risk of overtreatment

Question 22

How do you monitor hypothyroidism/medication?

Answer 22

Initially TFTs every 3 months
Can take up to 6 months for TSH to stabilise

Question 23

How is levothyroxine titrated?

Answer 23

In steps of 25mcg

Question 24

What happens if TSH is within normal limits BUT symptoms are still present?

Answer 24

Test FT4 to investigate secondary hypothyroidism

Question 25

When monitoring secondary hypothyroidism what should you do?

Answer 25

Only adjust dose dependent on FT4

Question 26

Which medication influence the thyroid?

Answer 26

Dopamine Glucocorticoid Iodine Metal ions Phenobarbital Beta-blockers

Question 27

How do you take levothyroxine?

Answer 27

Take 30-60 mins before food or other medications

Question 28

What are the interactions with levothyroxine?

Answer 28

Food - eg. milk Medicines - eg. calcium, Fe, PPIs Disease - eg. IBD/Coeliac

Question 29

What are side effects of levothyroxine?

Answer 29

Flushing Palpitations Insomnia Angina Thyroid crisis

Question 30

How is hypothyroidism + pregnancy linked?

Answer 30

Uncontrolled hypothyroidism can impair fertility Insufficient thyroid hormone can have teratogenic effects

Question 31

What happens if you're pregnant + have hypothyroidism?

Answer 31

Need frequent TSH level monitoring Increase levothyroxine dose dose by 25-50mcg