Thyroid (easy peasy!) Dr Lucie Spooner- F1

The plan 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 Prolactin GH ACTH TSH Posterior: ADH Oxytocin

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

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

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?

Primary Autoimmune 1. 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.

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

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

Hypothyroid- Investigations Investigations: How are they split up? BedsideBloodsRadiology Special Tests

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

Bloods FBC shows macroscopic anaemia (MCV ). FBC shows macroscopic anaemia (MCV ). - If Hb 115) or iron deficiency anaemia from menorrhagia TFT: Low T4 and high TSH- primary. TFT: Low T4 and high TSH- primary. Low or normal TSH- secondary or tertiary. Low or normal TSH- secondary or tertiary. Cortisol: exclude Addison's Cortisol: exclude Addison's Thyroid antibodies Thyroid antibodies

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

Management Conservative: lifestyle- weight loss, exercise (only subclinical!) Conservative: lifestyle- weight loss, exercise (only subclinical!) –If subclinical- check antibodies- if negative and asymtpomatic- screen annually. –2% chance of clinical signs annually. Medical: Medical: –50ug/day and increasing to ug/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! Surgical: see surgical lecture!

Myxoedema Coma: 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.

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

Hyperthyroidism- clinical signs Tremor Tremor Eye complaints (Grave’s) Eye complaints (Grave’s) –Proptosis –Dry eye –Difficulty looking up –Lid lag –Opthalmoplegia Pretibial Myxoedema and acropachy (Grave’s) Pretibial Myxoedema and acropachy (Grave’s) Atrial Fibr illation Atrial Fibr illation

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

What do you see?

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

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

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

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

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

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

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

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

Thyroid Function Test. First line is ONLY TSH. Lab will not check T3/T4 unless the TSH is deranged. First line is ONLY TSH. Lab will not check T3/T4 unless the TSH is deranged. T4 normal range is T4 normal range is TSH normal range is TSH normal range is Hypothyroidism: Hypothyroidism: –Primary- TSH is > 6. Secondary- TSH is low to normal. –T4/T3 low. Hyperthyroidism 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)

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.

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

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

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

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

Key Points 1. Remember to ask about red flag symptoms. 2. With a thyroid case they may hide the glass of water- look for it. 3. Don’t forget to treat symptoms as well as the disease- e.g. Beta blockers. 4. Talk slowly and breath... They want to pass you. I promise. 5. Practise, practise and practise....

Any Questions?