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Thyroid (easy peasy!)

Thyroid (easy peasy!). Dr Lucie Spooner- F1. The plan.... . 1. Anatomy- zzzzz 2. HPA Axis 3. Hypothyroidism 4. Thyrotoxicosis 5. Carbimazole- what you need to know 6. Surgical complications 7. Thyroid and pregnancy 8. Cases x4. . Pituitary Gland- just learn these. . Anterior: FSH LH

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Thyroid (easy peasy!)

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  1. Thyroid (easy peasy!) Dr LucieSpooner- F1

  2. The plan.... 1. Anatomy- zzzzz 2. HPA Axis 3. Hypothyroidism 4. Thyrotoxicosis 5. Carbimazole- what you need to know 6. Surgical complications 7. Thyroid and pregnancy 8. Cases x4.

  3. Pituitary Gland- just learn these. Anterior: FSH LH Prolactin GH ACTH TSH Posterior: ADH Oxytocin

  4. Definitions • Hypothyroidism: • clinic state from decreased production of and/or effect of thyroid hormones • Hyperthyroidism: • clinical state of increased circulation of free thyroid hormones. Excessive Thyroxine (T3 or T4 or both).

  5. Hypothyroidism- clinical features • Weight gain • Cold intolerance • Hair loss and Dry skin • Bradycardia • Pericardial effusion • Premature IHD • Constipation • Menstrual Disturbances • Menorrhagia (Anaemia) • Amenorrhoea (Rare) • Mentally Slow • Depression • Psychosis • Cerebellar disturbances • Facial puffiness • Bilateral Carpal Tunnel Syndrome • Slow relaxing reflexes • Hair loss

  6. Hypothyroidism- Causes Caused by thyroid (primary) the pituitary (secondary) or the hypothalamus (tertiary). PRIMARY: Autoimmune • There are 3 main examples- what are they? Primary: Acquired - There are 3 main causes- what are they?

  7. Primary Autoimmune • Hashimoto's thyroiditis: - autoimmune, very common, familial. - Autoantibody to thyroglobulin and thyroid= goitre. - Family members may have Addison's, pernicious anaemia or diabetes. - It is 10 times more common in women - anti-thyroid peroxidase and also anti-Tg antibodies 2. Atrophic hypothyroidism: - autoimmune, elderly, autoantibody to TSH receptor. - No goitre. 3. Congenital Hypothyroidism: -should be picked up in first 4 weeks or high risk of mental retardation- screened neonatally.

  8. Primary- Acquired: 1. Iodine deficiency (Endemic goitre). 2. Iodine excess (Amiodarone). 3. Post treatment for Hyperthyroidism. • Surgery • Radioiodine • Antithyroid Drugs (such as???)

  9. Hypothyroidism- Causes Secondary • Pituitary failure= Low levels of TSH • Very rare- just mention it.

  10. Hypothyroid- Investigations Investigations: How are they split up? Bedside Bloods Radiology Special Tests

  11. Bedside- 1. ECG: • a prolonged Q-T interval • low P, T and QRS amplitude • atrioventricular and intraventricular conduction disturbances e.g. right bundle branch block • 2. BM

  12. Bloods • FBC shows macroscopic anaemia (MCV 95-110). - If Hb <100 suspect an additional cause. Can have pernicious anaemia (MCV>115) or iron deficiency anaemia from menorrhagia • TFT: Low T4 and high TSH- primary. • Low or normal TSH- secondary or tertiary. • Cortisol: exclude Addison's • Thyroid antibodies

  13. Investigations- • Who would you screen ? • Perimenopausal women and those with non specific symptoms • Confusion • T1DM (especially those attempting to conceive)

  14. Management • Conservative: lifestyle- weight loss, exercise (only subclinical!) • If subclinical- check antibodies- if negative and asymtpomatic- screen annually. • 2% chance of clinical signs annually. • Medical: • 50ug/day and increasing to 125-150ug/day. • Half an hour before food or won’t be absorbed. • Check free thyroxine at 6-8 week intervals • If patient remains symptomatic- what would you do? • Surgical: see surgical lecture!

  15. Myxoedema Coma: Rare complication with 50% mortality rate. Suspect in any patient with hypothermia or coma. Start IV T3 (20ug bolus repeated every 6 hours). As thyroid failure may relate to pituitary disease (if Na is low), give hydrocortisone too until an accurate diagnosis is made.

  16. Hyperthyroidism- Symptoms Weight loss Increased appetite Irritability/restlessness Palpitations Heat intolerance Diarrhoea Oligomenorrhoea

  17. Hyperthyroidism- clinical signs • Tremor • Eye complaints (Grave’s) • Proptosis • Dry eye • Difficulty looking up • Lid lag • Opthalmoplegia • Pretibial Myxoedema and acropachy (Grave’s) • Atrial Fibrillation

  18. Pretibial myxoedema Anterior aspect lower legs Indurated discoluration of the skin.

  19. What do you see?

  20. Thyroid Eye Disease Occurs in Grave’s disease Exopthalalmus Proptosis Opthalmoplegia May be unilateral May present for the first time after treatment More common in smokers Rarely resolves completely. Causes: deposition of lymphocytes and oedema. Risk of optic nerve compression- can cause blindness, so Rx with steroids and surgery when ‘malignant exopthalmus’

  21. Thyrotoxicosis (give me 4 causes) • Grave’s disease • 75% cases • Thyroid-stimulating immunoglobulins (TSIs). • Thyroglobulin. • Thyroid peroxidase • Sodium-iodide symporter. • TSH receptor. • Goitre, eye signs and Pretibial Myxoedema • Toxic multi nodular goitre • 15% • Older women • Likely remission after medical therapy. • Toxic nodule/adenoma • 5%, • Likely remission after medical therapy • De Quervains thyroiditis • Transient from acute inflammatory viral process • Accompanied fever, malaise and pain in neck • Amiodarone induced Thyrotoxicosis • Postpartum thyroiditis • Iatrogenic - too much thyroxine • Hashimotos’s thyroiditis- .... Before you go hypo

  22. Investigations • Bedside: • ECG, Urine dip, BM • Bloods: • Serum TSH < 0.05mU/L • Raised free T4 or T3 confirms diagnosis • Thyroid antibodies • Radiology: • USS if lump/nodule • Special tests: • Radioisotope iodine scanning (hot or cold nodule) • FNA for cytology (more relevant if cancer suspected)

  23. Thyrotoxic storm – medical emergency Rapid deterioration of hyperthyroidism with 10% mortality Severe tachycardia, restlessness, hyperpyrexia, cardiac failure Precipitated by stress, infection or surgery in the unprepared patient High dose BB and start carbimzole or propylthiouracil immediately and give iodide and hour later and IV steroids to inhibit new thyroid hormone production.

  24. Management • Conservative: • Lubricant eye drops such as methylcellulose • Stop smoking • Tape eye lids to ensure closure at night • Systemic steroids 30-120mg OD to reduce inflammation if severe • Medical: • Beta Blockers – alleviated symptoms such as tremor and palpitations, normally the first Rx initiated. • Antithyroid drugs: • Carbimazole - inhibit formation of thyroid hormone • Propythiouracil - safe in pregnancy • Radioactive iodine • Contraindicated in pregnancy • Patients must be euthyroid before treatment • Can lead to hypothyroidism • Surgical: • Thyroidectomy

  25. Carbimazole • Grave’s: • Use for 18-24 months and then trial without medication • Side effects: • Most common: Urticrial rash (2-4%) • Most serious: Agranulocytosis (1/300-500) • Arthralgia • Headache • Alopecia. • Normally develop within 4 weeks of treatment. • If fever or sore throat- stop medication immediately. • Most patients feel better after 10 -14 days. • Takes 4-6 weeks before euthyroid.

  26. Complications after thyroidectomy • Immediate: • Haemorrhage • Recurrent larangeal nerve palsy • Intermediate: • Infection • Long-term: • Hypothyroidism • Hypoparathyroidism

  27. Pregnancy and thyrotoxicosis Hyperthyroidism in pregnancy HCG is a weak stimulator of TSH receptor Very important to treat Untreated leads to miscarriage, premature labour, low birth weight and eclampsia. Radioiodine is absolutely contraindicated.

  28. Thyroid Function Test. • First line is ONLY TSH . Lab will not check T3/T4 unless the TSH is deranged. • T4 normal range is 12-20. • TSH normal range is 0.6-6.0 • Hypothyroidism: • Primary- TSH is > 6. Secondary- TSH is low to normal. • T4/T3 low. • Hyperthyroidism • TSH is <0.05 • T3/T4 raised as a result of negative feedback (high T4 and low TSH can also be found in Exac of COPD, RA and HF, raised T3 however is always thyrotoxicosis)

  29. Case 1 39 year old lady presents with 3 months history of weight loss and diarrhoea. On further questioning you find out that she has been suffering from excessive sweating and a recent family holiday to Tunisia was ruined as she was unable to tolerate the weather. Her eyes also feel gritty a lot of the time and she has had friends ask her why she is staring at them. She is otherwise well and her only medication is St John’s Wort. She has no known allergies. She does not smoke and drinks alcohol socially. On exam she is slight with sweaty palms and a fine tremor when her arms are out stretched. Her pulse is 100bpm and irregularly irregular. She has exophthalmos and lid lag. She also has a diffuse non tender swelling on the front of her neck which moves with swallowing.

  30. What are your differentials for this lady? (make sure these include all important differentials that must be ruled out) How would you investigate her? How would you manage her? What are the cardinal features of Grave’s disease? What drug is used in pregnant hyperthyroid patients? What are complications of thyroid surgery?

  31. Case 2 T4 is 12. TSH is 7 Subclinical ?would you treat? Only if symptomatic or trying to conceive- must check for autoantibodies.

  32. Case 3 Pt admitted with fast AF TSH is undetectable T4 of 36 What would you do? Measure T3 in this case as could be secondary to heart failure. T3 is always raised in thyrotoxicis. If elevated T3 – start antithyroid medication.

  33. Case 4 45 yo lady with palpitations, weight loss. TSH undetectable T4 is 40 Which Rx would help control her symptoms fastest? Beta Blocker... Then antithyroid medication.

  34. Key Points • Remember to ask about red flag symptoms. • With a thyroid case they may hide the glass of water- look for it. • Don’t forget to treat symptoms as well as the disease- e.g. Beta blockers. • Talk slowly and breath... They want to pass you. I promise. • Practise, practise and practise....

  35. Any Questions?

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