Clinical Thyroid Disease Flashcards
What does the hypothalamus secrete to stimulate the thyroid?
TRH
What does the thyroid secrete?
T3 Triiodothyronine
T4 Thyroxine
What are the symptoms of hypothyroid?
Weight gain Goitre Mood changes Dry skin/hair Heavy periods Feeling Cold Lethargy Bradycardia
What are the symptoms of severe hypothyroid?
Puffy face
Large tongue
Hoarseness
Coma
What are the symptoms of hyperthyroid?
Weight loss Overheating Anxiety/irritability Bowel frequency Sweaty palms Palpitations Tremors Goitre Thyroid eye signs
How does primary Hypothyroidism present hormonally?
Raised TSH
Low T3, T4
How does subclinical Hypothyroidism present hormonally?
Raised TSH
Normal T3, T4
How does secondary Hypothyroidism present hormonally?
Low TSH
Low T3, T4
How common is hypothyroidism?
2% of women
0.1% of men
How common is congenital hypothyroidism?
1:3500
What are the causes of primary hypothyroidism?
Congenital
- Developmental
- Dyshormonogenesis
Acquired
What are the causes of acquired primary Hypothyroidism?
Autoimmune (hashimotos)
Iatrogenic
Chronic iodine deficiency
Post-subacute thyroiditis
What procedures have a risk of causing hypothyroidism?
Post-op Post-radiotherapy Post radioactive iodine Antithyroid drugs Amiodarone Lithium Interferon
What are the causes of secondary/tertiary hypothyroidism?
Pituitary tumour Craniopharyngioma Post-pituitary surgery Sheehan's syndrome Isolated THR deficiency
What is the effect of low T3/T4 on TSH, TRH?
Elevated TSH
Elevated TRH
How is hypothyroidism investigated?
TSH
T4
Thyroid peroxidase antibodies
(FBC, Lipids, Na+, ALT, PLT)
How is hypothyroidism treated?
Levothyroxine (T4) at 50mcg/day → 100mcg
Until dose normal
Annual testing of TSH after stabilising
(Liothyronine (T3)?)
How is hypothyroidism treated if they present with ischaemic heart disease?
Start at a lower dose 25mcg
Increase slowly
(risk angina)
Which factors require special treatment if the patient is hypothyroid?
Ischaemic heart disease
Pregnancy
Postpartum thyroiditis
Myxedema coma
How is hypothyroidism treated if they present with pregnancy?
Increase in LT4 dose
How is hypothyroidism treated if they present with postpartum thyroiditis?
Trial withdrawal and measure TFTs in 6 weeks
How is hypothyroidism treated if they present with myxedema coma?
May need IV T3
When is treatment considered in subclinical hypothyroidism?
TSH > 10
TSH > 5 with +ve thyroid antibodies
TSH elevated with symptoms
When the patient is considering pregnancy/pregnant
What are the risks of overtreatment of subclinical hypothyroidism?
Osteopenia
Atrial fibrillation
What is the line of therapy for subclinical hypothyroidism?
Trial therapy 3-4months
Continue if symptomatic improvement
Inadequate hypothyroid treatment during pregnancy is associated with what?
Foetal loss
Lower IQ
How is hypothyroid treatment different in pregnancy?
Increased LT4 by 25% and monitor closely
Keep TSH in low normal range
Keep FT4 in high normal range
Treat subclinical hypothyroidism if planning pregnancy
What are the causes of goitre?
Physiological: Puberty, pregnancy Autoimmune: Graves', Hashimotos Thyroiditis (acute or chronic) Iodine deficiency Dyshormonogenesis Giotrogens
What are the types of goitre?
Tumour Cyst Sarcoid, TB Diffuse (colloid/simple) Multinodular
What is the risk associated with solitary nodule thyroid?
Risk malignancy:
<30 or >60, child
Previous H&N radiation
Cervical lymphadenopathy
How is a solitary nodule thyroid investigated?
Thyroid function test
Ultrasound
FINE NEEDLE ASPIRATION
Isotope scanning if low TSH
What is a hot/cold nodule?
Cold: Nodule of thyroid which isnt functioning
Hot: Nodule of thyroid which functions
What are the different types of thyroid cancer?
Papillary Follicular Anaplastic Lymphoma Medullary
What is papillary thyroid cancer?
Common
Muiltifocal lesions
Local lymphatic spread
Good prognosis
What is follicular thyroid cancer?
Usually single lesion
Metastases to lung/bone
Good prognosis if resectable
Thyroid cancer has poor prognosis when?
<16, >45
Spread outside thyroid capsule
TNM stage
How is thyroid cancer treated?
Near total thyroidectomy
Ablative high dose radioiodine
Long term suppressive doses of thyroxine
THYROGLOBULIN
What is anaplastic thyroid cancer?
<5%
Aggressive, local invasion
Very poor prognosis
External RT
What is thyroid lymphoma?
Rare
?Preexisting hashimotos thyroiditis
External RT and chemo
What is medullary thyroid cancer?
Tumour of Parafollicular C-cells
Elevated serum calcitonin
What is the treatment for medullary thyroid cancer?
Total thyroidectomy
Medullary thyroid cancer is associated with what?
MEN 2
Phaeochromocytoma
Hyperparathyroidism
What are the primary causes of thyrotoxicosis?
Grave’s disease
Toxic multinodular goitre
Toxic adenoma
What are the secondary causes of thyrotoxicosis?
Pituitary adenoma secreting TSH
What are the causes of thyrotoxicosis without hyperthyroidism?
Destructive thyroiditis
Amiodarone
Excessive thyroxine
What is the biggest cause of hyperthyroidism?
Grave’s disease - 70-80%
What is the prevalence of Grave’s disease?
2-3:1000
2% female
0.16% male
What is the cause of Grave’s disease?
Autoimmune
- Thyroid peroxidase antibodies
- TSH receptor antibodies
- Review FH for autoimmune disease
What are the symptoms of Graves’ disease?
Hyperthyroidism Eye bulging Clubbing Gynaecomastia Goitre Pretibial myxedema
How is thyrotoxicosis disease diagnosed?
Hyperthyroidism symptoms Thyroid antibodies (TSH receptor)
What is multi-nodular goitre?
Most common cause of thyrotoxicosis in the elderly
Goitre in absense of Grave’s disease
WIll not go into spontaneous remission
Most common cause of thyrotoxicosis in the elderly?
Multi-nodular goitre
How does Subacute (de Quervain’s) thyroiditis usually present?
<50y/o Viral trigger Painful goitre +/- fever/myalgia ESR raised 3-6 weeks thyrotoxicosis 3-6 months hypothyroidism
How is Subacute (de Quervain’s) thyroiditis treated?
Short term steroid
NSAIDs
What are the most common treatments for thyrotoxicosis?
Surgery
Radiation
Antithyroid drugs
Beta blockers (symptoms)
What drugs are used to treat hyperthyroidism?
Carbimazole
Propylthiouracil
(Titrate or replacement)
What are the side effects of antithyroid drugs?
Hypothyroidism (30%)
Rash
Agranulocytosis
Which patients are best suited for antithyroid drugs?
Elderly
Cardiac complications
Unwilling to have radioiodine
What are the two forms of radioiodine therapy for hypothyroidism?
High dose ablative:
(90% cure, 70% hypothyroid)
Variable/calculated:
(60-90% cure, less hypo)
When is radioiodine avoided?
Severe eye disease
What is subclinical hyperthyroidism?
Suppressed TSH
Normal free thyroid hormones
What concerns are associated with subclinical hyperthyroidism?
Postmenopausal reduced bone density
3x risk AF over 60s
When is treatment considered for subclinical hyperthyroidism?
Antithyroid/RAI
In elderly
Increased cardiac risk
Which drug can cause destructive thyroiditis?
Amiodarone
What are the symptoms of agranulocytosis?
Sudden onset:
Sore throat
Fever
Rigors
What must radioiodine patients be aware of?
Pls dnt get preggers
Don’t go near children for 2-3 weeks