L22: Thyroid disorders Flashcards
What are the main functions of the thyroid hormones?
Control metabolism
Growth and development
What systems in the body are affected by thyroid disease?
Almost all systems Affects energy Weight Temperature Heart rate Nervous system GI system Musculoskeletal Skin
How is release of thyroid hormones from the thyroid gland controlled?
TRH released from hypothalamus stimulates AP
TSH released from AP stimulates thyroid gland
T3/4 released from thyroid gland
↑ T3/4 act back on the AP and hypothalamus to inhibit further release –> negative feedback
What happens to the levels of hormones in an underactive thyroid?
Low T3/4
High TSH
Primary hypothyroidism
What happens to the levels of hormones with an overactive thyroid?
High T3/4
Low TSH
Primary hyperthyroidism
What methods are used to view the thyroid gland?
Thyroid ultrasound
Radio isotope scans–> thyroid scintigraphy
–> Uses technetium 99m
Plain X-ray or CT scan
What are some of the different ectopic thyroid nodules?
Hot nodule–> englarged thyroid nodule but only on one side
Toxic multinodular goitre
Lingual thyroid
What is hypothyroid? What are the symptoms?
Low thyroid hormones
Myxeodema–> swollen eyes, thickened skin, deepened voice
Tiredness, weight gain, cold intolerance, changes in appearance, depression, psychosis, joint/muscle ache, dry hair/skin, constipation, puffy eyes
What are the signs of hypothyroidism?
Peri-orbital oedema Loss of eyebrows Dry, thin hair Bradycardia Slow-relaxing reflexes Carpal tunnel syndrome Cold peripheries
What are the causes of hypothyroidism?
Auto-immune atrophic Hashimoto's thyroiditis (get Goitre) Post partum thyroiditis Dyshormonogenesis Medication Iodine deficiency --> can't produce thyroid hormone
How is hypothyroidism treated?
Thyroxine replacement therapy –> Levothyroxine (T4)
- -> For life
- -> Starting dose depends on severity
- -> 100 micrograms for young and fit person
- -> More caution in elderly and heart disease–> could cause tachycardia–> trigger angina
- -> Resolution takes 6-8 weeks
What are the special situations in hypothyroidism to be aware of?
Myxoedema coma–> pt low temperature and low pulse
- -> Severe hypothyroidism- usually elderly, usually rare
- -> Hypothermia and fluid overload in heart- pericardial effusion
- -> 50% mortality so it require high dependency treatment
Borderline or sub-clinical hypothyroidism
- -> Low/normal T4 with very high TSH–> very common
- -> Monitored until symptoms appear
What is hyperthyroidism? What are the symptoms?
High thyroid levels--> overactive Weight loss Irritability Restlessness Insomnia Malasise Itching Sweating Palpitations Tremor Muscle ache Diarrhoea
What are the signs of hyperthyroidism?
Tremor Hyperkinesis--> muscles spasm Tachycardia Atrial fibrillation Warm peripheries Hypertension Proximal myopathy Lid Lag--> eye lids open wider
What are the causes of hyperthyrodism?
Graves disease–> autoimmune disease
Nodular thyroid disease–> lumpy thyroid, secretes excess thyroid (not autoimmune)
Thyroiditis–> Inflammation, destructive release
What is Graves disease?
Most common hyperthyroidism
Autoimmune mediated stimulation of TSH receptor
By thyroid stimulating immunoglobulin (TSI)
High levels of T3,4, Low TSH
What causes Graves opthalmopathy?
Autoimmune antibody’s target fibroblasts in the eye muscles
Fibroblast turn into adipocytes
Fat cells and muscles expand and become inflammed
Veins become compressed–> oedema
Optic nerve can become compressed/stretched as eye is pushed out–> blindness if not relieved
What is Graves dermopathy?
aka pertibial myxoedema
Skin on anterior leg becomes red, itchy and thickened
What is thyroid acropachy?
Acropachy–> thickening of extremities
Triad of things: digital clubbing, swelling of soft tissue in hands and feet, periosteal bone formation
Sign of thyrotoxicity –> over treatment with thyroid drugs or overactive thyroid
What is nodular hyperthyroidism?
Single toxic nodule or multiple nodules
Single aka hot nodule
What is thyroiditis? What causes it?
Inflammation of thyroid Release of thyroxine into circulation Viral infection--> de quervain's thyroiditis After childbirth--> post partum Medication--> amiodarone
How is hyperthyroidism treated?
Medication
Surgery
Radioactive iodine
What medication is given to treat hyperthyroidism?
Carbimazole or propylthioutacil (thionamides)
Beware of agranulocytosis –> neutropenia –> supress immune system –> pt get rash or fever immediately stop medication and get FBC
Beta blockers–> control the symptoms –> block sympathetic function
What is the surgical procedure done to treat hyperthyroidism?
Done if side effects to medication or patient preference
Removal of thyroid gland
Small risk of laryngeal nerve pasly and hypocalcaemia (damage to parathyroid gland)
What is the radioactive treatment for iodine?
Good non surgical option
Contra-indicated in pregnancy
Mute thyroid gland–> radioactive iodine given
Must follow radiation restriction guidance after treatment
What are the special situations in hyperthyroidism?
Thyroid crisis/ thyroid storm–> rare condition–> 10% mortality
- -> Hyperpyrexia, tachycardia, cardiac failure, liver dysfunction
- -> Need urgent treatment on high dependency unit
Hyperthyroidism and pregnancy
- -> Graves disease- antibodies cross the placenta
- -> Baby born with hyperthyroidism
- -> Requires close monitoring in pregancy
What is Goitre?
Means swelling of thyroid
7% female, 1% males
What are the different types of goitre?
Diffuse goitre --> Simple --> Autoimmune thyroid disease or Thyroiditis Nodular goitre --> Multinodular goitre --> Solitary nodule--> Red Flag Fibrotic goitre --> Riedel's thyroiditis--> rare --> Associated with midline fibrosis Iodine deficient --> Common worldwide --> Rare in UK
What are the red flag symptoms for thyroid cancer?
History --> Very young or old --> Rapid enlargement of lump in neck --> Hoarse voice an dysphagia --> Family history of thyroid cancer Examination --> Hard irregular thyroid mass --> Fixed to surrounding structures --> Cervical lymph nodes
How would investigate suspected thyroid cancer?
Thyroid ultrasound
Fine needle aspiration
CT scan thorax and mediastinum
How would you treat suspected thyroid cancer?
Removal of thyroid
Surgery–> must be done by expert–> laryngeal nerve palsy, hypocalcaemia
Large tumour–> radioiodine ablation
