Case 7 - Thyroid Disease - Progress Test

Question 1

What causes thyroid hormones to be released?

Answer 1

• Hypothalamus secretes thyrotropin-releasing hormone (TRH)
• This stimulates the anterior pituitary to secrete thyroid-stimulating hormone (TSH)
• This stimulates the thyroid to release T3 (triiodothyronine) and T4 (thyroxine)

Question 2

What do thyroid hormones do in the body?

Answer 2

They act on a variety of tissues to:

• help regulate the use of energy sources
• help regulate protein synthesis
• control the body’s sensitivity to other hormones

Question 3

What is primary hypothyroidism caused by?

Answer 3

A problem with the thyroid gland

eg. an autoimmune condition

Question 4

What is secondary hypothyroidism caused by?

Answer 4

A problem with the pituitary gland
(eg. pituitary apoplexy)

or a lesion compressing the pituitary gland

Question 5

What is congenital hypothyroidism?

Answer 5

A problem with thyroid dysgenesis

or thyroid dyshormonogenesis

Question 6

What is the main type of hyperthyroidism?

Answer 6

Primary hyperthyroidism

Question 7

What is the most common pathology assoicatied with hypothyroidism?

Answer 7

Hashimoto’s thyroiditis

Question 8

What is Hashimoto’s thyroiditis and what other conditions is it associated with?

Answer 8

An autoimmune disease

Associated with:

• type 1 DM
• Addison’s
• Pernicious anaemia
• Vitiligo

Hashimoto’s is assoicated with development of MALT lymphoma

Question 9

What are the other causes of hypothyroidism?

Answer 9

• Subacute thyroiditis (de Quervain’s)
  (causes a painful goitre and a raised ESR)
• Riedel thyroiditis
  (causes a painless goitre. The normal tissue is replaced by fibrous tissue)
• Post-partum thyroiditis
• Drugs: lithium, amiodarone
• Iodine deficinecy

Question 10

What is the most common pathology associated with hyperthyroidism?

Answer 10

Grave’s disease

thyroid eye disease may also be seen

Question 11

What are the other causes of hyperthyroidism?

Answer 11

Toxic multinodular goitre
(treatment of choice = radioiodine)

Drugs: amiodarone

Question 12

What are the symptoms of hypothyroidism?

Answer 12

• Weight gain
• Lethargy
• Cold intolerance
• Dry, cold, yellowish skin
• Dry, coarse scalp hair
• Loss of the lateral aspect of the eyebrows
• Constipation
• Menorrhagia
• Decreased deep tendon reflexes
• Carpal tunnel syndrome

Question 13

What are the symptoms of thyrotoxicosis?

Answer 13

• Weight loss
• Manic restlessness
• Heat intolerance
• Palpitations (may provoke arrhythmias)
• Pre-tibial myxoedema
• Thyroid acropachy (clubbin)
• Diarrhoea
• Oligomenorrhea
• Anxiety
• Tremor

Question 14

What would investigations for primary hypothyroidism show?

Answer 14

High TSH

Low free T4

Question 15

What would investigations for secondary hypothyroidism show?

Answer 15

Low TSH

Low free T4

Question 16

What would investigations for sick euthyroid syndrome show?

Answer 16

Low TSH

Low free T4

Question 17

What would investigations for subclincial hypothyroidism show?

Answer 17

High TSH

Normal free T4

Question 18

Would would investigation in patients with poor complicance to thyroxine show?

Answer 18

High TSH

Normal free T4

Question 19

Would would investigations for primary hyperthyroidism show?

Answer 19

Low TSH

High free T4

Question 20

What antibodies are seen in Graves’ disease?

Answer 20

TSH receptor antibodies

Question 21

What antibodies are seen in Hashimoto’s thyroiditis?

Answer 21

anti-TPO antibodies

anti-thyroglobulin (Tg) antibodies may also be seen

Question 22

What investigation would be used to diagnose toxic multinodular goitre?

Answer 22

Nuclear scintigraphy

Toxic multinodular goitre reveals patchy uptake

Question 23

How is hypothyroidism managed?

Answer 23

Thyroxine

Question 24

How is hyperthyroidism managed?

Answer 24

Propanolol for symptomatic relief

Carbimazole

Radioiodine treatment

Question 25

What is the pharacology of carbimazole?

Answer 25

Carbimazole blocks thyroid peroxidase from coupling and iodinating the thyrosine residues on thyroglobulin - reducing thyroid hormone production

Question 26

What is an important side effect of carbimazole?

Answer 26

Agranulocytosis (dangerously low WBC count)

Question 27

How is carbimazole taken?

Answer 27

Taken OD for 6-9 months Then withdrawn to see if in remission Thyroixine is added once the patient is euthyroid

Question 28

How long should you avoid contact with children and pregnant women after radioiodine treatment?

Answer 28

3 weeks

Question 29

What complication of hyperthyroidism can be worsened by radioiodine treatment?

Answer 29

Thyroid eye disease

Question 30

How is thyroid eye disease prevented from worsening after radioiodine treatment?

Answer 30

Prednisolone

Question 31

How are thyroid cancers investigated?

Answer 31

Thyroid US | Fine needle aspiration

Question 32

What are some side effects of levothyroxine?

Answer 32

Hyperthyroidism (due to over treatment) Osteoporosis (reduced bone mineral density) Worsening angina AF

Question 33

What does of levothyroxine should be given initially?

Answer 33

50-100mcg. 25 mcg should be given in patients over 50 and those with cardiac disese or severe hypothyroidism, and then slowly titrated up.

Question 34

When should thyroid levels be checked after starting levothyroxine?

Answer 34

8-12 weeks

Question 35

What TSH range is levothyroixine hoping to achieve?

Answer 35

0.5-2.5

Question 36

How should a levothyroxine dose be adjusted in pregnancy?

Answer 36

Increase dose by at least 25-50 mcg of levothyroxine.

Question 37

What medications interact with levothyroxine?

Answer 37

Iron Calcium carbonate

Question 38

What is subacute thyroiditis?

Answer 38

Thyroiditis thought to occur following a viral infection

Question 39

What are the phases of subacute thyroiditis?

Answer 39

Phase 1 (3-6 weeks) : hyperthyroidism, painful goitre, raised ESR Phase 2 (1-3 weeks) : euthyroid Phase 3 (weeks to months) : hypothyroidism Phase 4 : thyroid structure and function returns to normal

Question 40

How is subacute thyroiditis investigated?

Answer 40

thyroid scintigraphy Shows globally reduced uptake of iodine-131

Question 41

How is subactue thyroiditis managed?

Answer 41

Usually self-limiting and doesn't require treatment Thyroid pain may respond to aspirin or NSAIDs In more severe cases, or if hypothyroidism develops, then steroids are used

Question 42

What is post-partum thyroiditis and how is it managed?

Answer 42

Thyrotoxicosis, followed by hypothyroidism, followed by normal thyroid function. anti-TPO is found in 90% of cases. Management: - Propanolol in the thyrotoxic phase - Thyroxine in the hypothyroid phase

Question 43

What can trigger a thyroid storm?

Answer 43

- Surgery - Trauma - Infection - Acute iodine load eg. CT contrast media

Question 44

What are the clinical features of a thyroid storm?

Answer 44

``` Fever > 38.5 Tachycardia Confusion and agitation Nausea and vomiting Hypertension Heart failure Abnormal liver function tests (may be jaundiced) ```

Question 45

How is a thyroid storm managed?

Answer 45

Symptomatic treatment: - Paracetamol - beta blockers eg. propanolol IV Treat underlying cause Anti-thyroid drugs: - methimazole or - propylthiouracil Lugol's iodine Dexamathasone - 4mg IV qds (blocks conversion of T4 to T3)