Clinical Thyroid Disease Flashcards
What are some examples of thyroid diseases?
Hypothyroidism
Goitre
Thyroid cancer
Hyperthyroidism
Give a summary of the hormones involved with the thyroid gland?
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What is the clinical manifestation of hypothyroidism?
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What is the clinical presentation of hyperthyroidism?
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Compare and contrast the clinical presentation of hyper and hypothyroidism?
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What are the different classifications of hypothyroidism?
- Primary (thyroid)
- Raised TSH, low FT4 and low FT3
- Subclinical (compensated)
- Raised TSH, normal FT4 and FT3
- Secondary (pituitary)
- Low TSH, low FT4 and FT3
Where is the pathology that causes primary hypothyroidism?
Thyroid gland
Where is the pathology that causes secondary hypothyroidism?
Pituitary gland
What TSH, FT3 and FT4 levels are seen in primary hypothyroidism?
Raised TSH
Low FT3
Low FT4
What TSH, FT3 and FT4 levels are seen in subclinical hypothyroidism?
Raised TSH
Normal FT3
Normal FT4
What TSH, FT3 and FT4 levels are seen in secondary hypothyroidism?
Low TSH
Low FT3
Low FT4
What are the 2 most common endocrine conditions?
1) Diabetes
2) Hypothyroidism
Does hypothyroidism affect men and woman equally?
No, affects more woman
What are some causes of primary hypothyroidism?
- Congenital
- Developmental
- Agenesis/maldevelopment
- Dyshormonogenesis
- Trapping/organification
- Incidence of congenital hypothyroidism is 1/3500
- All babies in UK screened
- Developmental
- Acquired
- Autoimmune thyroid disease
- Hashimotos/atrophic
- Iatrogenic
- Postoperative/post-radioactive iodine
- External RT for head and neck cancers
- Antithyroid drugs (such as Lithium)
- Chronic iodine deficiency
- Post-subacute thyroiditis
- Post-partum thyroiditis
- Autoimmune thyroid disease
Are babies screened for hypothyroidism?
Yes, all babies are
What is the incidence of congenital hypothyroidism?
1/3500
What are some causes of secondary hypothyroidism?
- Pituitary/hypothalamic damage
- Pituitary tumour
- Craniopharyngioma
- Post pituitary surgery or radiotherapy
How does hormone secretion change in hypothyroidism?
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What investigations are done for hypothyroidism?
- TSH/fT4
- Autoantibodies
- TPO (thyroid peroxidase antibodies)
- FBC (MCV raised)
- Lipids (hypercholesterolaemia)
- Hyponatremia due to SIADH
- Increased muscle enzymes (ALT, CK)
- Hyperprolactinaemia
What autoantibody is investigated in hypothyroidism?
TPO (thyroid peroxidase antibodies)
What does TPO stand for?
Thyroid peroxidase antibodies
What is used for the treatment of hypothyroidism?
- Levothyroxine (T4) tablets
- Liothyronine (T3) tablets
- Combination of T3 and T4 has no benefit from studies
- After stabilisation, annual testing of TSH
What is the first line treatment for hypothyroidism?
Levothyroxine tablets (T4)
What is the initial dose of levothyroxine for hypothyroidism?
1.6mcg/kg
How does ischaemic heart disease impact the initial treatment for hypothyroidism?
Lower dose of levothyroxine used (25mcg) and increased cautiously
When should treatment be given for subclinical hypothyroidism?
If TSH > 10
or TSH > 5 with symptoms therapy should be trialed for 6 months
If subclinical hypothyroidism is diagnosied, when should tests be repeated?
2-3 months later with TPO antibodies
How does pregnancy impact treatment for hypothyroidism?
- Increased levothyroxine requirements during pregnancy
- Inadequately treated hypothyroidism linked with increased foetal loss and lower IQ
- At diagnosis of pregnancy
- Increase LT4 dose by about 25% and monitor closely
- Aim to keep TSH in normal range (<2.5mU/L) and FT4 in high normal range
What is inadequately treated hypothyroidism during pregnancy associated with?
Increased foetal loss and lower IQ
What is goitre?
Swelling of the thyroid gland
What is swelling of the thyroid gland called?
Goitre
What are some causes of goitre?
- Physiological
- Puberty
- Pregnancy
- Autoimmune
- Graves disease
- Hashimoto’s disease
- Thyroiditis
- Acute (de Quervian’s)
- Chronic fibrotic (Reidel’s)
- Iodine deficiency (endemic goitre)
- Dyshormogenesis
- Goitrogens
What are some different goitre types?
- Multinodular goitre
- Diffuse goitre
- Colloid
- Simple
- Cysts
- Tumours
- Adenomas
- Carcinoma
- Lymphoma
- Miscellaneous
- Sarcoidosis
- Tuberculosis
What tumours can cause goitre?
Adenoma
Carcinoma
Lymphoma
What is solitary nodule thyroid?
Defined as palpable discrete swelling within an otherwise normal gland
What risk comes with solitary nodule thyroid?
Risk of malignancy (5% chance)
What investigations are done for solitary nodule thyroid?
- Thyroid function test
- Solitary toxic nodule
- Ultrasound
- Useful in differentiating between benign and malignant
- Fine needle aspiration (FNA)
- Thy1 is inadequate
- Thy2 is benign to Thy5 which is cancer
What is the most common endocrine malignancy?
Thyroid cancer
What are the different classifications of thyroid cancer?
- Papillary
- Commonest
- Multifocal, local spread to lymph nodes
- Good prognosis
- Follicular
- Usually single lesion
- Metastases to lung/bone
- Good prognosis if resectable
Which form of thyroid cancer is the most common, papillary or follicular?
Papillary
Where does papillary thyroid cancer often spread to?
Local spread to lymph nodes
Where does follicular thyroid cancer often metastasis to?
Lung or bone
What is the management of thyroid cancer?
- Prognosis poorer
- Age <16 or >45, tumour size, spread outside thyroid capsule and metastases, TNM stage
- Near total thyroidectomy
- High dose radioiodine (ablative)
- Long term suppressive doses of thyroxine
- Follow up
- Thyroglobulin
Whole body iodine scanning
What surgery can be done to treat thyroid cancer?
Thyroidectomy
Other than follicular and papillary thyroid cancer, what are some other thyroid cancers?
Anaplastic
Lymphoma
Medullary thyroid cancer
What does anoplastic thyroid cancer not respond to?
Radioiodine
What is lymphoma thyroid cancer best treated with?
External RT, combined with chemotherapy
What does the tumour that causes medullary thyroid cancer arise from?
Parafollicular C cells
What genetic syndrome is medullary thyroid cancer associated with?
MEN2
What is the treatment for medullary thyroid cancer
Total thyroidectomy
No role for radioiodine
How does hyperthyroidism impact hormones?
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What are some causes of hyperthyroidism?
- Primary
- Grave’s disease (70%)
- Toxic multinodular goitre (20%)
- Toxic adenoma
- Secondary
- Pituitary adenoma secreting TSH
- Thyrotoxicosis without hyperthyroidism
- Destructive thyroiditis
- Excessive thyroxine administration
What is the most common cause of primary hyperthyroidism?
Grave’s disease (70%)
What is thyrotoxicosis?
Excess thyroid hormone in the body
What are some causes of thyrotoxicosis without hyperthyroidism?
Destructive thyroiditis
Excessive thyroxine administration
What is the M:F ratio of Grave’s disease?
1:5 (more females affected)
What kind of condition is Grave’s disease?
Autoimmune condition
What antibodies are present in grave’s disease?
Thyroid peroxidase antibodies
TSH receptor antibodies
What is the diagnosis of Grave’s disease done by?
Hyperthyroidism present
Thyroid antibodies (TSH receptor antibodies)
What is the most common cause of thyrotoxicosis in the elderly?
Multinodular goitre
What triggers subacute (de Quervain’s) thyroiditis?
Viral trigger (enteroviruses, coxsackie)
What is the clinical presentation of subacute (de Quervain’s) thyroiditis?
Painful goitre
Maybe fever/myalgia
ESR increased
What treatment may subacute (de Quervain’s) thyroiditis require?
Short term steroids and NSAIDs
What is the management of hyperthyroidism?
- RAI (radioiodine)
- High dose ablative
- Patients usually choose ATD before RAI
- Treat with ATP (stop 4-7 days before and after)
- ATD (anti-thyroid drugs)
- Carbimazole
- Propylthiouracil
- Sx
- Beta blockers
What are examples of anti-thyroid drugs?
Carbimazole
Propylthiouracil
What are some concerns for patients with subclinical hyperthyroidism?
- Bones
- Decreased bone density postmenopausal, no clear fracture data
- Atrial fibrillation
- 3x increased risk in over 60s
What treatment is considered for subclinical hyperthyroidism and when?
ATP/RAI if persistent, especially in elderly or those with increased cardiac risk