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Thyroid Notes

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Thyroid Notes

  1. 1. - St. George’s thyroid exam Thyroid HypothalamusTRH (thyrotrophin releasing hormone) Anterior pituitaryTSH (thyroid stimulating hormone) ThyroidT4T3 in peripheries
  2. 2. - St. George’s thyroid exam Primary disease= in the thyroid itself Secondary=in pituiaty (very rare) Tests  Free T4 and t3 (sometimes in hyperthyroidism), more useful than total levels as this is affected by protein carrier levels (which is affected by drugs, pregnancy, hepatitis, nephrotic syndrome..etc)  TSH  Thyroid autoantibodies – antithyroid peroxidase and antithyroglobulin antibodies. Maybe increased in autoimmune disease (Hashimotos or Graves)  TSH receptor antibodies (Graves)  US – determines cystic (usually benign) from solid nodules  Isotope scan – can detect ectopic thyroid tissue or carcinoma. Hot (increased uptake), cold and neutral nodules – hot and neutral nodules are usually not malignant. TSH, T4 Hypothyroidism TSH, normal T4 Treated/subclinical hypothyroidism TSH, T4 TSH tumour or hormone resistance TSH, T4 Hyperthyroidism TSH, normal T4 Subclinical hyperthyroidism TSH,  T4 Sick euthyroidism Sick euthyroidism = deranged TFTs in illness (usually everything becomes low) Goitre  Can be associated with hypothyroidism or hyperthyroidism. Most causes can lead to a goitre  Most common cause worldwide is iodine deficiency  Can be caused by a diffuse enlargement (iodine) or due to nodular enlargement (neoplasm)  Nodules can be inactive or active (aka toxic) Hyperthyroidism  Thyrotoxicosis often used synonymously  Causes o Autoimmune = Graves disease o Infective = De Quervain’s thyroiditis  A self limiting, acute, severe post viral hyperthyroidism (coxsackie, adenovirus or URTI). Leads to a characteristically painful goitre o Neoplastic = toxic adenoma o Iatrogenic = drugs such as amiodarone or lithium. Also from over treating hypothyroidism  Symptoms o Increased metabolismweight loss and increased appetite o Heat intolerance o Sweating
  3. 3. - St. George’s thyroid exam o Diarrhoea o Tremor o Irritability/restlessness o Psychosis o Itch o Oligomenorrhoea  Signs o Increased pulse rate o atrial fibrillation o palmar erythema o hair thinning o lid retraction o goiter, nodules or bruites o Graves  eye signs – exophthalmos (abnormal connective tissue deposition in the orbit and extraocular muscles due to fibrosis following lymphocyte infiltration), ophthalmoplegia (paralysis of muscles by similar mechanism), lid retraction and lid lag. Eyelid retraction is the most common sign of ophthalmopathy. Von Graefe's sign (lid lag sign) is the immobility or lagging of the upper eyelid on downward rotation of the eye. Abnormal wideness of the eye due to retraction of both lids is called Dalrymple’s sign and is noticed due to large area of whiteness above and below the iris (particularly above). In moderate active disease, the signs and symptoms are persistent and increasing and include myopathy. The inflammation and edema of the extraocular muscles lead to gaze abnormalities. The inferior rectus muscle is the most commonly affected muscle and patient may experience vertical diplopia on upgaze and limitation of elevation of the eyes due to fibrosis of the muscle. Protosis is a description of bulging eyes  Pretibial myxoedema - It usually presents itself as a waxy, discolored induration of the skin—classically described as having a so-called peau d'orange (orange peel) appearance  thyroid acropatchy - painful clubbing of fingers or toes and periosteal limb bone reaction  Treatments o Medical  beta blockers for symptoms  either titrate with carbimazole  or block with carbimazole and replace with thyroxine  SE of carbimazole is agranulocytosis (can  septic neutropaenia, watch out for illness)  Propylthiouracil is another alternative  Antithyroid medicines inhibit thyroid peroxidase  Radioiodine can be used to ablate the thyroid but almost invariably leads to hypothyroidism. Can  thyroid storm
  4. 4. - St. George’s thyroid exam  2 major contraindications to radioiodine are pregnancy and lactation o Surgery  Subtotal thyroidectomy  Thyroid storm - also referred to as thyrotoxic crisis, is an acute, life- threatening, hypermetabolic state induced by excessive release of thyroid hormones (THs) in individuals with thyrotoxicosis. Thyroid storm may be the initial presentation of thyrotoxicosis in undiagnosed children, particularly in neonates. The clinical presentation includes fever, tachycardia, hypertension, and neurological and GI abnormalities. Hypertension may be followed by congestive heart failure that is associated with hypotension and shock. Because thyroid storm is almost invariably fatal if left untreated, rapid diagnosis and aggressive treatment are critical.  Graves disease o Autoimmune – antibodies stimulating TSH receptors o 60% have eye signs o strong genetic component – many genes involved (incl. HLA-DR3) o TSH antibodies not routinely tested o Other antibodies against thyroid peroxidase and thyroglobulin in 75% of patients which can be measured using agglutination/ELISA/immunofluorescence Hypothyroidism  Causes o Autoimmune  Hashimoto’s thyroiditis – goiter. Destruction of thyroid tissue, mechanism not understood. May start as hyperthyroidism. HLA DR4 and 3. Acute phase may be hyperthyroidism.  Primary myxedema – no goiter, atrophy. Blocking of TSH receptor with autoantibodies (same as Grave’s but opposite effect). HLA DR4 o Environmental/dietary – iodine deficiency. In countries without iodinised salt o Iatrogenic – thyroidectomy or drugs (amiodorone, lithium) o Congenital  cretinism. Now screened for using the Guthrie heel prick test 5 days postnatally.  Symptoms o Tiredness o Lethargy o Depression o Cold intolerance o Weight gain o Constipation o Menorrhagia o Hoarse voice o Dementia  Signs o Bradycardia o Dry skin and hair
  5. 5. - St. George’s thyroid exam o Ataxia o Slow reflexes o Peripheral neuropathy  Treatment o Replace what is missing – give levothyroxine  Thyroid function screening o Those with other autoimmune conditions – vitiligo, Addison’s or type 1 (or gestational) diabetes o Those on amiodorone or lithium (6 monthly) o Hyperlipidaemia o Atrial fibrillation o Certain genetic conditions that have a strong association eg Turner’s and Down’s syndrome Reference ranges: Calcium 2.1-2.6 mmol/l Phosphate 0.8-1.4 mmol/l CRP < 10 mg/l Thyroid stimulating hormone (TSH) 0.5-5.5 mu/l Free thyroxine (T4) 9-22 pmol/l Total thyroxine (T4) 70-140 nmol/l Amylase 70-300 u/l Uric acid 0.18-0.48 mmol/l SBAs 1. A 23-year-old woman presents with sweating and tremor. Her thyroid function tests are as follows: TSH <0.05 mU/l Free T4 25 pmol/l What is the most common cause of this presentation? A . Hashimoto's thyroiditis B . Graves' disease C . Toxic nodular goitre D . De Quervain's thyroiditis
  6. 6. - St. George’s thyroid exam E . Toxic adenoma 2. A 33-year-old female is referred by her GP with thyrotoxicosis. Following a discussion of management options she elects to have radioiodine therapy. Which one of the following is the most likely adverse effect? A . Hypothyroidism B . Thyroid malignancy C . Agranulocytosis D . Oesophagitis E . Precipitation of thyroid eye disease 3. A 36-year-old woman presents with feeling tired and cold all the time. On examination a firm, non-tender goitre is noted. Blood tests reveal the following: TSH 34.2 mU/l Free T4 5.4 pmol/l What is the most likely diagnosis? A . Primary atrophic hypothyroidism B . Pituitary failure C . De Quervain's thyroiditis D . Iodine deficiency E . Hashimoto's thyroiditis 4. A 43-year-old woman presents for follow-up in clinic. She was diagnosed with Hashimoto's thyroiditis four months ago and is currently being treated with levothyroxine 75 mcg od. What is the single most important blood test to assess her response to treatment? A . ESR B . TSH
  7. 7. - St. George’s thyroid exam C . Free T4 D . Total T4 E . Free T3 5. A 40-year-old woman complains of feeling tired all the time and putting on weight. On examination a diffuse, non-tender goitre is noted. Blood tests are ordered: TSH 15.1 mU/l Free T4 7.1 pmol/l ESR 14 mm/hr Anti-TSH receptor stimulating antibodies Negative Anti-thyroid peroxidase antibodies Positive What is the most likely diagnosis? A . Pituitary failure B . Primary atrophic hypothyroidism C . De Quervain's thyroiditis D . Hashimoto's thyroiditis E . Grave's disease 6. A 52-year-old woman who was diagnosed as having primary atrophic hypothyroidism 12 months ago is reviewed following recent thyroid function tests (TFTs): TSH 12.5 mU/l Free T4 14 pmol/l She is currently taking 75mcg of levothyroxine once a day. How should these results be interpreted? A . Poor compliance with medication B Taking extra thyroxine
  8. 8. - St. George’s thyroid exam . C . Evidence of recent systemic steroid therapy D . Keep on same dose E . T4 to T3 conversion disorder Answers 1. Graves' disease is the most common cause of thyrotoxicosis in the UK. All the other conditions can cause thyrotoxicosis but are less common. Thyrotoxicosis Graves' disease accounts for around 50-60% of cases of thyrotoxicosis. Causes • Graves' disease • toxic nodular goitre • subacute (de Quervain's) thyroiditis • post-partum thyroiditis • acute phase of Hashimoto's thyroiditis (later results in hypothyroidism) • toxic adenoma (Plummer's disease) • amiodarone therapy Investigation • TSH down, T4 and T3 up • thyroid autoantibodies • other investigations are not routinely done but includes isotope scanning 2. It is well documented that radioiodine therapy can precipitate thyroid eye disease but a majority of patients eventually require thyroxine replacement Graves' disease: management Despite many trials there is no clear guidance on the optimal management of Graves' disease. Treatment options include titration of anti-thyroid drugs (ATDs, for example carbimazole), block-and-replace regimes, radioiodine treatment and surgery. Propranolol is often given initially to block adrenergic effects ATD titration • carbimazole is started at 40mg and reduced gradually to maintain euthyroidism • typically continued for 12-18 months • patients following an ATD titration regime have been shown to suffer fewer side-effects than those on a block-and-replace regime Block-and-replace
  9. 9. - St. George’s thyroid exam • carbimazole is started at 40mg • thyroxine is added when the patient is euthyroid • treatment typically lasts for 6-9 months The major complication of carbimazole therapy is agranulocytosis Radioiodine treatment • contraindications include pregnancy (should be avoided for 4-6 months following treatment) and age < 16 years. Thyroid eye disease is a relative contraindication, as it may worsen the condition • the proportion of patients who become hypothyroid depends on the dose given, but as a rule the majority of patient will require thyroxine supplementation after 5 years 3. Hashimoto's thyroiditis = hypothyroidism + goitre + anti-TPO The combination of a goitre with hypothyroidism points to a diagnosis of Hashimoto's. De Quervain's thyroiditis typically causes a painful goitre. Hashimoto's thyroiditis Hashimoto's thyroiditis is an autoimmune disorder of the thyroid gland. It is typically associated with hypothyroidism although there may be a transient thyrotoxicosis in the acute phase. It is 10 times more common in women Features • features of hypothyroidism • goitre: firm, non-tender anti-thyroid peroxidase and also anti-Tg antibodies 4. Hypothyroidism: management Key points • initial starting dose of levothyroxine should be lower in elderly patients and those with ischaemic heart disease (e.g. 25-50 mcg/day) • following a change in thyroxine dose thyroid function tests should be checked after 6-8 weeks • the therapeutic goal is 'normalisation' of the thyroid stimulating hormone (TSH) level. As the majority unaffected people have a TSH value 0.5-2.5 mU/l it is now thought preferable to aim for a TSH in this range • there is no evidence to support combination therapy with levothyroxine and liothyronine Side-effects of thyroxine therapy • hyperthyroidism: due to over treatment • reduced bone mineral density • worsening of angina • atrial fibrillation
  10. 10. - St. George’s thyroid exam 5. this patient has Hashimoto's thyroiditis, as evidenced by the hypothyroidism, goitre and anti-thyroid peroxidase antibodies. De Quervain's thyroiditis typically causes a painful goitre and a raised ESR. Around 90% of patients with Grave's disease have anti-TSH receptor stimulating antibodies. 6. Thyroid function tests The interpretation of thyroid function tests is usually straightforward: TS H Free T4 Thyrotoxicosis (e.g. Graves' disease) Low High In T3 thyrotoxicosis the free T4 will be normal Primary hypothyroidism (primary atrophic hypothyroidism) Hig h Low Secondary hypothyroidism Low Low Replacement steroid therapy is required prior to thyroxine Sick euthyroid syndrome* Low ** Low Common in hospital inpatients Poor compliance with thyroxine Hig h Norm al / high Steroid therapy Low Norm al *now referred to as non-thyroidal illness **TSH may be normal in some cases
  11. 11. - St. George’s thyroid exam OSCE 1. Wash hands, introduce, gain permission, expose (down to clavicles), reposition (sitting). Ask if they have any pain 2. General inspection a. Body habitus – overweight = hypo, under=hyper b. Clothing – appropriate for weather? Over dressed = hypo, under =hyper c. Hair – greasy=hyper, dry=hypo d. Eye brows – lost outer 2/3rds = hypo e. Anxious/restless 3. Inspection of hands (VET SOAP) V – vitiligo (indicator of autoimmune disease) E – erythema of palms T – tremor (ask patient to hold hands out and can put a piece of paper on top to highlight fine tremor) S - sweating O - onycholysis A – acropatchy – Graves disease specific P – pulse (bradycardia=hypo, tachycardia/AF=hyper) 4. Inspection of neck a. Scars, Sinuses, Swellings, Skin changes b. Ask patient to stick tongue out – thyroglossal cysts move up c. Ask patient to swallow water – goitres move up as attached to pre-tracheal fascia 5. Inspection of eyes (Grave’s disease) a. Look – from above and to sides do the eyes protrude beyond the supraorbital ridge i.e. proptosis/exophthalmos b. Ask patient to follow an H and ask them to tell you if they see any diplopia to test for Ophthalmoplegia c. Ask patient to follow finger from top to bottom for lid lag 6. Palpate the neck a. Stand behind and palpate bimanually b. Describe size, shape, site, smoothness, symmetry, consistency, fluctuance, tenderness, tethering. Thyroid specific – diffuse or single. Smooth or multinodular. Could offer to transluminate (cysts). c. Palpate asking patient to stick tongue out and swallow water d. Palpate for lymph nodes e. Palpate for centrally located trachea 7. Percuss retrosternally for retrosternal goitre 8. Auscultate for thyroid bruit while patient holds their breath(very suggestive of Grave’s) 9. Legs a. Inspect for pretibial myxoedema
  12. 12. - St. George’s thyroid exam b. Ask patient to hold arms out like a chicken against resistance and stand from sitting with their arms crossed– proximal myopathy (hypothyroidism) c. Test reflexes. Brisk = hyper, slow=hypo 10. Thank the patient, offer to help them get dressed 11. Wash hands

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