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Endocrine System > Clinical Thyroid Disease > Flashcards

Clinical Thyroid Disease Flashcards

1
Q

Name four thyroid diseases

A
  • Hypothyroidism
  • Goitre
  • Thyroid Cancer
  • Hyperthyroidism
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2
Q

How is TH release stimulated?

A

Hypothalamus -> anterior pituitary releases TSH -> T3 and T4

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3
Q

What are the key symptoms of hypothyroidism?

A
  • Weight Gain
  • Lethargy
  • Feeling cold
  • Constipation
  • Heavy periods
  • Dry Skin/Hair
  • Bradycardia
  • Slow reflexes
  • Goitre
  • Severe – puffy face, large tongue, hoarseness, coma
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4
Q

What are the key symptoms of hyperthyroidism?

A
  • Weight Loss
  • Anxiety/Irritability
  • Heat Intolerance
  • Bowel frequency
  • Light periods
  • Sweaty palms
  • Palipitations
  • Hyperreflexia/Tremors
  • Goitre
  • Thyroid eye symptoms/signs
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5
Q

What are the three different catergories of hypothyroidism?

A
  • Primary (thyroid not producing hormone)
  • Subclinical (compensated)
  • Secondary (pituitary not releasing TSH to stimulate thyroid)
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6
Q

What is subclinical hypothyroidism?

A

Early, mild form of hypothyroidism - subclinical because only the serum level of thyroid stimulating hormone from the front of the pituitary gland is a little bit above normal.

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7
Q

What are the level of TSH and FT3/4 in hypothyroidism?

A
  • Primary - raised TSH, low FT3+4
  • Subclinical - raised TSH: normal FT3+4
  • Secondary - low TSH, low FT3+4

(FT3 is triiodothyronine and FT4 is thyroxine)

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8
Q

Name causes of primary hypothyroidism

A
  • Congenital

* Acquired

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9
Q

Describe the congenital causes of primary hypothyroidism

A

Developmental
• Agenesis / maldevelopment

Dyshormonogenesis
• Trapping / organification / dehalogenase

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10
Q

Describe the acquired causes of primary hypothyroidism

A
  • Autoimmune thyroid disease (hashimotos / atrophic)
  • Iatrogenic (post-op, external RT for head + neck cancers, antithyroid drugs, Amiodarone)
  • Chronic iodine deficiency
  • Post-subacute thyroiditis (post partum thyroiditis)
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11
Q

What are the causes of secondary /tertiary hypothyroidism?

A 
Pituitary/hypothalamic damage:
• Pit. tumour 
• Craniopharyngioma 
• Post pituitary surgery or RT 
• Sheehan's syndrome 
• Isolated TRH deficiency
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12
Q

What are the two main investigations for hypothyroidism?

A
  • TSH / fT4

* Autoantibodies: TPO (thyroid peroxidase antibodies)

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13
Q

What are the treatment strategies for hypothyroidism?

A

Levothroxine (T4) tablets
• 50mcg/day, after 2 weeks increase to 100mcg
• Increase until TSH normal

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14
Q

What is the treatment of hypothyroidism in special situations?

A
  • Ischaemic heart disease - start lower at 25mcg, risk of angina
  • Pregnancy - increase in LT4 dose
  • Postpartum thyroiditis - trial withdrawal and measure TFTs in 6 weeks
  • Myxedema coma - rare emergency, may need IV T3 (steroid)
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15
Q

What is the treatment of subclinical hypothyroidism?

A
  • TSH > 10
  • TSH > 5 with positive thyroid antibodies
  • TSH elevated with symptoms - trial therapy for 3/4 months and continue if symptomatic treatment
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16
Q

What are the risks of over treatment of hypothyroidism?

A

Osteopenia and atrial fibrillation

17
Q

Describe hypothyroidism in pregnancy

A

• Increase levothyroxine requirements
• Inadequate treatment -> increase foetal loss and lower IQ
• Treat subclinical hypothyroidism is pregnant
• At diagnoses of pregnancy:
- Increase LT4 by 25%
- Keep TSH in low normal range and FT4 in high normal range

18
Q

Name causes of Goitre

A

Physiological:
• Puberty
• Pregnancy

Autoimmune:
• Graves disease
• Hashimotos disease

  • Thyroiditis (acute or chronic)
  • Iodine deficiency (endemic goitre)
  • Dyshormogenesis
  • Goitrogens
19
Q

What are the different types of goitre?

A
  • Multinodular goitre
  • Diffuse goitre (colloid or simple)
  • Cysts
  • Tumour (adenoma, carcinoma, lymphoma)
  • Miscellaneous (sarcoidosis, TB)
20
Q

Describe the features of a solitary nodule thyroid

A

Risk of malignancy
• Child
• < 30yrs but > 60yrs
• Pain, cervical lymphadenopathy

  • Large dominant nodule of MNG also needs investigation
  • 5% chance of malignancy
21
Q

What are the investigations of a solitary thyroid nodule?

A
  • TFT (solitary toxic nodule)
  • Ultrasound (benign vs malignant)
  • Fine needle aspiration!!
  • Isotope scanning if low TSH (hot nodule)
22
Q

What is a hot or cold nodule?

A

If a nodule is composed of cells that do not make thyroid hormone (don’t absorb iodine), then it will appear “cold” on the x-ray film. A nodule that is producing too much hormone will show up darker and is called “hot.”

23
Q

Describe the different types of thyroid cancer

A

Papillary:
• Multifocal, local spread to lymph nodes

Follicular:
• Usually single lesion
• Metastases to lung/bone

24
Q

What is the management of thyroid cancer?

A
  • Poorer prognosis: age < 16 or > 45
  • Near total thyroidectomy
  • High dose radioiodine (ablative)
  • Long term suppressive doses of thyroxine

Follow up:
• Thyroglobulin
• Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal or recombinant TSH injections)

25
Q

What are other types of thyroid cancers?

A

Anaplastic:
• Aggressive, locally invasive
• Very poor prognosis, do not respond to radioiodine, external RT brief help

Lymphoma:
• Rare; arise from hashimotos thyroiditis
• External RT more helpful, combined with chemo

26
Q

What are the features of medullary thyroid cancer?

A
  • Tumour arise from parafollicular C cells
  • Often associated with MEN 2 (phaeochromocytoma & hyperparathyroidism)
  • Serum calcitonin levels raised
27
Q

What is the treatment of medullary thyroid cancer?

A

Total thyroidectomy (no role for radioiodine)

28
Q

What is thyrotoxicosis?

A

Excess of thyroid hormone in the body (hyperthyroidism)

29
Q

What are causes of thyrotoxicosis?

A

Primary:
• Graves disease
• Toxic multi nodular goitre
• Toxic adenoma

Secondary:
• Pituitary adenoma secreting TSH

Thyrotoxicosis without hyperthyroidism:
• Destructive thyroiditis, Amiodarone
• Excessive thyroxine administration

30
Q

What is Grave’s disease?

A

Autoimmune driven condition:
• Thyroid peroxidase antibodies
• TSH receptor antibodies
• Review personal/FH for concurrent autoimmune disease

31
Q

How do you diagnose Grave’s disease?

A
  • Hyperthyroidism

* Thyroid antibodies (TSH receptor antibodies)

32
Q

What are the clinical features of Graves’ disease?

A
  • Goitre
  • Exophthalmos (bulging of eyes)
  • Tremor
  • Arrhythmia and tachycardia
  • Nausea and diarrhoea
  • Gynaecomastia
  • Finger clubbing
33
Q

What is multi-nodular goitre?

A
  • Most common cause of thyrotoxicosis in elderly
  • Characteristic goitre and absence of Grave’s disease
  • No spontaneous remission
34
Q

What are the features of subacute (de Quervain’s) thyroiditis?

A
  • Generally younger patients < 50 years
  • Viral trigger (eg enteroviruses, coxsackie)
  • Often recall painful goitre +/- fever/myalgia; ESR increased
  • May require short term steroids and NSAIDs
35
Q

Describe the timeline of subacute thyroiditis?

A

Acute stage of thyrotoxicosis lasts 3-6 weeks and then often followed by hypothyroidism for 3-6 months

36
Q

Give examples of antithyroid drugs (ATD)

A

• Carbimazole (CMZ) or propylthiouracil (PTU)

37
Q

Describe the course of antithyroid drugs (ATD)

A

Titration regimen:
Dose of drugs reduced so until lowest dose is effective

Block and replace:
Use of CMZ and PTU, to stop thyroid gland to produce TH, and take levothyroxine to replace hormone

38
Q

What the features of subclinical hyperthyroidism?

A
  • TSH suppressed
  • Normal Free thyroid hormone
  • Concerns: decreased bone sensitivity in post-menoapause and x3 risk of AF in over 60s
  • Treatment considered ATD/RAI if persistent especially in elderly or those with increased cardiac risk

Endocrine System (29 decks)

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