Clinical Thyroid Disease

Question 1

What pathologies come under the heading of thyroid disease

Answer 1

• Hypothyroidism
• Goitre
• Thyroid cancer
• Hyperthyroidism

Question 2

State the difference between primary and secondary thyroid disease

Answer 2

• Primary = Problem originates in the thyroid gland
• Secondary = Problem originates in the hypothalamus/pituitary gland

Question 3

What are the symptoms of hypothyroidism?

Answer 3

• Lethargy
• Sleepiness/ tiredness
• Weight GAIN
• Feeling cold/cold disliking
• Constipation
• ↓Mood
• Heavy periods

Question 4

What are the signs of hypothyroidism?

Answer 4

Pneumonic: BRADYCARDIC

• Bradycardia
• Reflexes are slow (slow reflexes)
• Ataxia (cerebellar)
• Dry skin/hair
• Yawning/ drowsy/coma (severe cases)
• Cold hands
• Ascites
• Round puffy face
• Defeated demeanour
• Immobile
• Congestive cardiac failure (CCF)

Question 5

Differentiate between the thyroid function test (TFT) findings in primary, secondary and subclinical hypothyroidism

Answer 5

•Primary (Thyroid):

Raised TSH, Low FT4 & FT3

•Subclinical (Compensated):

Raised TSH: Normal FT4 & FT3

•Secondary (Pituitary):

Low TSH, Low FT4 & FT3

Question 6

Prevalence: How common is hypothyroidism in relation to other endocrine conditions?

Answer 6

• 2nd most common endocrine condition (after diabetes)

Question 7

What are the causes of primary hypothyroidism?

Answer 7

Causes of primary hypothyroidism

May be CONGENITAL or ACQUIRED:

Congenital causes:

• Developmental (failure of an organ, i.e. the thyroid gland fails to develop during embryonic development)
• Dyshormonogenesis (genetic defect in the synthesis of thyroid hormone)

Acquired causes:

• Autoimmune thyroid disease (i.e. Hashimoto’s thyroiditis)
• Iatrogenic (post-thyroidectomy, post-radioactive iodine treatment, antithyroid drugs, amiodarone, lithium, interferon)
• Chronic iodine deficiency
• Post-subacute thyroiditis

Question 8

What is does for all babies in the uk in terms of hypothyroidism?

Answer 8

– All babies screened in the UK

Question 9

What are the causes of secondary hypothyroidism?

Answer 9

Pituitary/hypothalamic damage:

• Primary tumour
• Craniopharyngioma (benign brain tumour)
• Post pituitary surgery or radiotherapy

Question 10

How do we investigate hypothyroidism?

Answer 10

• Check levels of TSH and T4:

↑TSH and ↓T4 in primary hypothyroidism while ↓TSH and ↓T4 in secondary hypothyroidism

• Autoantibodies: Thyroid peroxidase antibodies (↑ in autoimmune thyroid disease)

Other investigations:

BLOODS:

• FBC (MCV increased)
• Lipids (hypercholesterolaemia)
• Hyponatremia (due to SIADH)
• Increased muscle enzymes, ALT, CK
• Hyperprolactinaemia

Question 11

How do we treat hypothyroidism?

And what is the initial dose in adults?

And what should be done for patients after stabalisation?

Answer 11

• Levothyroxine (T₄) tablets (synthetic T₄)
• Initial dose for adults < 65 years old = 1.6mcg/kg
• After stabilisation, annual testing of TSH

(Titrate in 25 mcg steps according to TFT until TSH stable/ normalised)

Question 12

Treatment of hypothyroidism (in special situations): LATER

Question 13

What is meant by subclinical hypothyroidism?

Answer 13

• TSH = High
• T₄ = NORMAL

(PassMedicine: “patients who are ‘on the way’ to developing hypothyroidism but still have normal thyroxine levels”)

Question 14

Hypothyoidism and Pregnancy (LATER)

Question 15

State the causes of goitre under the following headings:

(a) Physiological
(b) Autoimmune
(c) Other causes

Answer 15

(a) Physiological:
- Pregnancy
- Puberty
(b) Autoimmune
- Grave’s disease (antibodies bind to the TSH receptor that normally responds to TSH, causing an enlarged thyroid gland)
- Hashimoto’s disease (immune system attacks your thyroid)
(c) Other causes:
- Thyroiditis
- Iodine deficiency
- Goitrogens (substances that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. This triggers the pituitary to release thyroid-stimulating hormone (TSH), which then promotes the growth of thyroid tissue, eventually leading to goitre)
- Dyshormogenesis (genetic defects in the synthesis of thyroid hormones. Patients develop hypothyroidism with a goitre)

Question 16

What are the 2 main types of goitre?

Answer 16

2 main types of goitre:

• Multinodular
• Diffuse

Question 17

How do we investigate a solitary thyroid nodule?

Answer 17

• Thyroid function tests (TFTs)
• Ultrasound (differentiates between benign and malignant)
• Fine needle aspiration (FNA): Thy1 = Inadequete, Thy2 = Benign, Thy5 = Cancer

Question 18

State the 5 types of thyroid cancer

Answer 18

• Papillary
• Follicular
• Anaplastic
• Medullary
• Lymphoma

Question 19

DESCRIPTION OF THE DIFFERENT TYPES OF THYROID CANCER (LATER)

Answer 19

LATER

Question 20

What is Grave’s Disease and how do we diagnose it? (LATER)

Answer 20

LATER

Question 21

Subacute (de Quervain’s) thyroiditis:

(a) Viral triggers?
(b) Symptoms?
(c) Blood test results?
(d) Treatment?

Answer 21

(a) Enteroviruses, coxsackie
(b) Painful goitre +/- fever/myalgia
(c) ↑ESR
(d) Short term steroids and NSAIDs

Question 22

How do we manage hyperthyroidism?

Answer 22

Antithyroid drugs:

• Carbimazole (inhibits thyroid peroxidase, the enzyme required in the synthesis of thyroid hormones): Titrate according to the TFT’s or block and replace
• Propylthiouracil (preferred in the 1st trimester of pregnancy as carbimazole has an increased risk of congenital abnormalities. NICE then says to switch back to carbimazole at the beginning of the 2nd trimester)
• Radioiodine
• Surgery (subtotal thyroidectomy)
• Beta blockers (for symptom control)

Question 23

What are the side effects of antithyroid drugs?

Answer 23

• Rash
• Agranulocytosis (lowering of WBC count)

Question 24

In what cases would we offer long term low doses of anti-thyroid drugs?

Answer 24

• Elderly
• Cardiac complications
• Unwilling for RAI