Clinical Thyroid Disease Flashcards
What are the symptoms of hypothyroidism?
Weight gain Lethargy Feeling cold Constipation Heavy periods Dry skin/hair Bradycardia Slow reflexes Goitre If severe- puffy face, large tongue, hoarseness, coma
What are the symptoms of hyperthyroidism?
Weight loss Anxiety/irritability Heat intolerance Bowel frequency Light periods Sweaty palms Palpitations Hyperreflexia/tremors Goitre Thyroid eye symptoms/signs
What thyroid function tests would be expected of someone with primary hypothyroidism?
Raised TSH
Low FT4 and FT3
What thyroid function tests would be expected of someone with subclinical/compensated hypothyroidism?
Raised TSH
Normal FT4 and FT3
What thyroid function tests would be expected of someone with secondary hypothyroidism?
Low TSH
Low FT4 and FT3
What are the causes of primary hypothyroidism?
Congenital Autoimmune thyroid disease Iatrogenic Chronic iodine deficiency Post-subacute thyroiditis
What are the caused of secondary/tertiary hypothyroidism?
Pituitary/hypothalamic damage:
- Pituitary tumour
- Craniopharyngioma
- Post pituitary surgery or radiotherapy
- Sheehan’s syndrome
- Isolated TRH deficiency
What are the main investigations for hypothyroidism?
TSH/fT4
Autpantibodies- TPO (thyroid peroxidase antibodies)
How is hypothyroidism treated?
Levothyroxine (T4) tablets
Liothyronine (T3)
Initial dose lezothyroxine 50mg/day, increase dose until TSH normal
After stabilisation annual testing of TSH
When does hypothyroidism require special treatment?
Ischaemic heart disease- start at lower dose and increase cautiously as risk of inducing angina
Pregnancy- most need an increase in LT4 dose
Postpartum thyroiditis- trial withdrawal and measure TFTs in 6 weeks
Myxedema coma- very rare, may need IV T3
When is treatment of subclinical hypothyroidism indicated?
TSH >10
TSH >5 with positive thyroid antibodies
TSH elevated with symptoms
What are the risks of over treatment of subclinical hypothyroidism?
Osteopenia
Atrial fibrillation
What is the significance of hypothyroidism in pregnancy?
Increased levothyroxine requirements during pregnancy
Inadequately treated hypothyroidism linked with increased foetal loss and lower IQ
How should treatment of hypothyroidism be altered in pregnancy?
Increase LT4 dose by ~25% and monitor closely
Aim to keep TSH in low normal range and FT4 in high normal range
Treat subclinical hypothyroidism if planning pregnancy/pregnant
What are the causes of goitre?
Physiological: -Puberty -Pregnancy Autoimmune: -Grave's disease -Hashimoto's disease Thyroiditis (acute or chronic) Iodine deficiency Dyshormonogenesis Goitrogens
What are the different kinds of goitres?
Multinodular goitre Diffuse goitre (colloid or simple) Cysts Tumours (adenoma, carcinoma, lymphoma) Miscellaneous (Sarcoidosis, tuberculosis)
What are the red flags for malignancy in a solitary nodule thyroid?
Child
Adult less than 30 or over 60
Previous head and neck irradiation
Pain, cervical lymphadenopathy
How is a solitary thyroid nodule investigated?
Fine needle aspiration
Tyroid function test
Ultrasound- useful to differentiate benign/malignant
Isotope scanning if low TSH to test for hot nodule
What is the difference between a hot and cold thyroid nodule?
Hot thyroid nodules produce excess thyroid hormone
Cold thyroid nodules are non-functioning
What are the characteristics of papillary and follicular thyroid cancer?
Both differentiated Papillary: -Commonest -Multifocal with local spread to lymph nodes -Good prognosis Follicular: -Usually single lesion -Metastases to lung/bone -Good prognosis if resectable
Describe the management of thyroid cancer
Prognosis poorer if <16 or >45, large tumour or spread outside the thyroid capsule Near total thyroidectomy High dose radioiodine Long term suppressive doses of thyroxine Follow up: -Thyroglobulin -Whole body iodine scanning
What are the characteristics of anaplastic thyroid cancer?
Rarer
Aggressive and locally invasive
Do not respond to radioiodine, external radiotherapy may help briefly
What are the characteristics of thyroid lymphoma?
Rare- may arise from Hashimotos thyroiditis
External radiotherapy combined with chemotherapy can be helpful
What are the characteristics of medullary thyroid cancer?
Tumour arisen from parafollicular C cells
Often associated with MEN 2
Serum calcitonin levels raised
Treatment- total thyroidectomy, radioiodine not indicated
What are the causes of thyrotoxicosis?
Primary: -Grave's disease -Toxic multinodular goitre -Toxic adenoma Secondary: -Pituitary adenoma secreting TSH Thyrotoxicosis without hyperthyroidism: -Destructive thyroiditis -Excessive thyroxine administration
What are the characteristics of Grave’s disease?
Accounts for ~70% of cases of hyperthryoidism
F:M = 5:1
Autoimmune driven condition:
-Thyroid peroxidase antibodies
-TSH receptor antibodies
-Review personal/family history for concurrent autoimmune disease
How is Grave’s disease diagnosed?
Presence of hyperthyroidism
Thyroid antibodies- TSH receptor antibodies
What are the characteristics of a multi-nodular goitre?
Most common cause of thyrotoxicosis in the elderly
Characteristic goitre
Absence of Grave’s disease
What are the characteristics of subacute thyroiditis?
Also known as de Quervain’s thyroiditis
Generally patients <50
Viral trigger
Often recall painful goitre +/- fever/myalgia
ESR increased
May require short term steroids and NSAIDs
What are the side effects of antithyroid drugs?
Rash
Agranulocytosis
What are the common antithyroid drugs and how are they delivered?
Carbimazole
Propylthiouracil
Titration regimen over 12-18 months
What other treatment can be given for hyperthyroidism other than antithyroid drugs?
Radioiodine- contraindicated in pregnancy
Steroids
Surgery-thyroidectomy
What are the characteristics of subclinical hyperthyroidism?
TSH suppressed
Normal free thyroid hormones
Concerns- decreased bone density and atrial fibrillation
Treatment considered if persistent
