Thyroid Disorders Flashcards
Causes of hypothyroidism and associated general features:
- Hashimoto’s: most common developed world, autoimmune, transient thyrotoxicosis acute phase, 5-10 times more common in women
- Subacute (De Quervain’s) thyroiditis: painful goitre and raised ESR
- Riedel thyroiditis: fibrous tissue displacement, painless goitre
- Postpartum
- Drugs: lithium, amiodarone
- Iodine deficiency: most common developing world
Causes of hyperthyroidism:
- Grave’s disease
- Toxic multinodular goitre
- Drugs: amiodarone
Typical symptoms of hypothyroidism:
- cold intolerance
- weight gain
- lethargy
- dry, anhydrous, yellowish skin
- non-pitting oedema
- dry scalp
- loss of lateral aspect of eyebrow
- constipation
- menorrhagia
- decreased deep tendon reflexes
- carpal tunnel syndrome
Typical symptoms of hyperthyroidism:
- heat intolerance
- weight loss
- restlessness
- palpitations
- increased sweating
- pretibial myxoedema
- thyroid acropachy: clubbing
- diarrhoea
- oligomenorrhea
- anxiety and tremor
TSH and Free T4 in Thyrotoxicosis
- low TSH
- High T4
TSH and Free T4 in Primary Hypothyroidism
- high TSH
- low T4
TSH and Free T4 in Secondary Hypothyroidism
- low TSH
- low T4
TSH and Free T4 in sick euthyroid syndrome
- low/normal TSH
- low T4
TSH and Free T4 in subclinical hypothyroidism
- high TSH
- normal T4
TSH and Free T4 in poor compliance with thyroxine
- high TSH
- normal T4
Risk factor for Grave’s
smoking
Specific features of Grave’s disease
- eye signs (30%): exophthalmos, diplopia, ophthalmoplegia
- pretibial myxoedema
- thyroid acropachy
- autoantibodies: TSH receptor stimulating Ab (90%), anti-thyroid peroxidase Ab (75%)
Management of Grave’s disease
- propranolol to block adrenergic effects
- ATD titration (start carbimazole 40mg), 12-20 months
- block and replace (thyroxine when euthyroid), 6-9 months
- radioiodine (contra in pregnancy and <16yo)
What is Hashimoto’s associated with?
autoimmune disease, T1DM, Addison’s , pernicious anaemia
Secondary hypothyroidism causes:
- pituitary failure
- Down’s
- Turner’s
- Coeliac’s
Management of hypothyroidism:
- 50-100mcg levothyroxine od
- reduce to 25mcg od in elderly >50yo and ischaemic HD
- if changing dose, TFTs in 8-12 weeks
- increase dose by 25-50mcg in pregnancy
ADR of levothyroxine
- hyperthyroidism
- reduced bone mineral density
- worsening angina
- AF
Signs of congenital hypothyroidism:
- prolonged neonatal jaundice
- delayed mental and physical milestones
- short stature
- puffy face, macroglossia
- hypotonia
Screening for congenital hypothyroidism
at 5-7 days with heel prick test
Specific features in Hashimoto’s
- goitre firm non-tender
- anti-thyroid peroxidase and anti-thyroglobulin Ab
- assocaited with development of MALT lymphoma, coeliac, T1DM, vitiligo
Hormone profile, clinical features causes and treatment of primary hyperparathyroidism:
Hormones: -increased PTH -increased calcium -reduced phosphate -urine calcium: creatinine CR >0.01 -diagnose with technetium - MIBI subtraction scan Features: -may be asymptomatic -bones, stones, abdominal groans and psychic moans -polydipsia, polyuria -recurrent abdominal pain (peptic ulcers, constipation, pancreatitis) -changes to emotional state -pepperpot skull Causes: -solitary adenoma -hyperplasia -multiple adenoma -parathyroid carcinoma Treatment: -total parathyroidectomy -conservative if calcium <0.25mmol/L above upper limit and >50yo and no end organ damage -calcimimetic agents e.g. cinacalcet
Indications for surgery in primary hyperparathyroidism:
- increased serum calcium
- hypercalciuria
- reduced creatinine clearance
- episode of life threatening hypercalcaemia
- nephrolithiasis
- <50yo
- neuromuscular syndrome
- reduced bone mineral density
Hormone profile, clinical features and causes of secondary hyperparathyroidism:
Hormones: -increased PTH -increased phosphate -reduced calcium -reduced vit D Features: -bone disease -osteitis fibrosa -soft tissue calcifications Causes: -parathyroid gland hyperplasia -almost always in setting of chronic renal failure
Indications for surgery in secondary hyperparathyroidism:
- bone pain
- persistent pruritus
- soft tissue calcifications
Hormone profile, clinical features and causes of tertiary hyperparathyroidism:
Hormones: -increased PTH -normal or increased calcium -decreased or normal phosphate -decreased or normal vit D -increased ALP Features: -metastatic calcification -bone pain/fracture -nephrolithiasis -pancreatitis Causes: -ongoing parathyroid gland hyperplasia after correction of renal disorder
Management of tertiary hyperparathyroidism:
- allow 12 mo after transplant
- autonomously functioning may require surgery: excised or total parathyroidectomy and re-implanation of part of gland
Signs and features of primary hypoparathyroidism:
- reduced PTH
- reduced calcium
- increased phosphate
- e.g. secondary to thyroid surgery
- tetany, cramp and spasm, oral paraesthesia, Trousseau’s sign, Chvostek’s sign, chronic depression and cataracts, increased QT interval
What is Trousseau’s sign?
carpal spasm if brachial artery occluded by BP cuff
What is Chvostek’s sign?
tapping over parotid causes facial muscles to twitch
Signs and features of pseudohypoparathyroidism:
- target cells insensitive to PTH
- increased PTH, reduced calcium, increased phosphate
- low IQ, short, shortened 4th and 5th metacarpals
- diagnose with urinary cAMP and phosphate after infusion of PTH (regular hypothyroid cAMP and phosphate both increase)
- type I - no increase in either
- type II - no increase in phosphate
Why can you get thyroid problems in pregnancy?
- increase in thyroxine binding globulin
- increase total thyroxine but not free thyroxine
Thyrotoxicosis in pregnancy and management:
- untreated increased risk of foetal loss, maternal HF and premature labour
- Grave’s most common
- manage with propylthiouracil in first trimester
- carbimazole from second
- no block and replace or radioiodine
- keep maternal free thyroxine in upper third of normal to avoid foetal hypothyroidism
Hypothyroidism in pregnancy management:
- thyroxine safe in pregnancy and breastfeeding
- increased dose by 50% at 4-6 weeks
What are the phases of subacute (De Quervain’s) thyroiditis?
- 3-6 weeks: hyperthyroidism, painful goitre, raised ESR
- 1-3 weeks: euthyroid
- weeks-months: hypothyroidism
- thyroid structure and function back to normal
Investigations for Subacute thyroiditis:
thyroid scintigraphy: global uptake of iodine-131
Management of subacute thyroiditis:
- usually self-limiting
- may respond to aspirin or NSAIDs
- steroids if severe hypo
Presentation of subclinical hyperthyroidism:
- normal serum free thyroxine and triiodothyronine levels
- TSH below normal <0.1mu/L
Presentation and management of subclinical hypothyroidism:
- TSH raised but T3 and T4 normal
- TSH 4-10mu/L: trial levothyroxine if <65yo and symptomatic (avoid hormonal treatment in elderly), asymptomatic observe and repeat TFTs in 6 months
- TSH >10mu/L: treatment even if asymptomatic and <=70yo
Types of thyroid cancer:
- papillary: good prognosis
- follicular
- medullary: secrete calcitonin, part of MEN-2
- anaplastic: not responsive to Tx
- lymphoma: assoc with Hashimoto’s
Causes, prevention and management of thyroid eye disease:
- Grave’s disease
- autoimmune response causing retroorbital inflammation - glycosaminoglycan and collagen deposition in muscles
- smoking
- radioiodine Tx makes worse
- prednisolone may reduce risk
- treat with topical lubricants to prevent corneal inflammation, steroids, radiotherapy, surgery
Cause, precipitating factors, features and management of thyroid storm:
- complication of thyrotoxicosis
- surgery, trauma, infection, acute iodine load in CT contrast media
- fever, achy, confusion and agitation, n&v, HTN, HF, abnormal LFTs
- beta blockers, propylthiouracil and hydrocortisone
- paracetamol, Lugol’s iodine, dexamethasone
Interactions of levothyroxine:
iron and calcium carbonate - absorption reduced (give at least 4 hours apart)
