Hyperthyrodism, hypothyrodism and thyroditis Flashcards
What can cause secondary thyroid disease?
Hypothalamic or pituitary disease
No thyroid gland pathology
When and where is TSH released?
Released by thyotroph cells in the anterior pituirary in response to thyrotropin releasing hormone (THR)
What percentage of thyroxine in T4 and T3?
80% T4
20% T3
What will the thyroid function tests look like in primary hypothyrodism?
Free T3/4 low
TSH high
What will the thyroid function tests look like in primary hyperthyrodism?
Free T3/4 high
TSH low - often falls to 0
What will the thyroid function tests look like in secondary hypothyrodism?
Free T3/4 low
TSH low
What will the thyroid function tests look like in secondary hyperthyrodism?
Free T3/4 high
TSH high
What is myoxedema?
Severe hypothyrodism
What is pretibial myxodeme?
Rare clinical sign of graves disease
What can cause goitrous hypothyrodism?
Hashimoto's Iodine deficiency Drug induced - amiodarone, lithium Maternally transmitted - antithyroid drugs Heriditary biosynthetic defects
What can cause non-goitrous hypothyrodism?
Atrophic thyroditis
Post-ablative therpy (radioiodine, surgery)
Post-radiotherapy (lymphoma treatment)
Congenital developmental defect
What can cause self-limiting hypothyrodism?
Withdrawel of antithyroid drugs
Subacute thyrodidis
Post-partum thyroditis
What antibodies characterise hashimotos thyroditis?
Thyroid peroxidate (TPO) T-cell infiltrate and inflammation microscopically
What are the hair and skin features associated with hypothyrodism?
Coarse, sparse hair Dull face Periorbial puffiness Pale skin Vitiligo Hypercarotenaemia
What are the thermogenesis features associated with hypothyrodism?
Cold intolerance
What fluid retention can occur with hypothyrodism?
Pitting oedema
What are the cardiac features associated with hypothyrodism?
Bradycardia
Dilation
Pericardial effusion
Worsening of heart failure
What are the metabolic features associated with hypothyrodism?
Hyperlipidaemia
What are the metabolic rate features associated with hypothyrodism?
Decreased appetite
Weight gain
What are the GI features associated with hypothyrodism?
Constipation
What are the resp features associated with hypothyrodism?
Deep hoarse voice
Macroglossia
Obstructive sleep apnoea
What are the neurological features associated with hypothyroidism?
Decreased intellectual and motor activities Depression, psychosis Muscle stiffness Peripheral neuropathy Prolongation of tendon jerks Carpal tunnel syndrome Reduced visual acuity
What gynae features associated with hypothyroidism?
Mennorhagia
Amenorrhoea
Hyperprolactinaemia
What are the lab features associated with hypothyroidism?
Increased TSH and redueced fT4/3
Increased LDL
Hyponatraemia
Hyperprolactinaemia
What is the management of hypothyrodism?
Metabolic rate restored GRADUALLY as rapid restoration may precipitate cardiac arrhythmias
Levothyroxine 50-100 micrograms
How should the management of hypothyrodism be monitored?
Check TSH 2 months after any dose change
Once stabilised, TSH should be checked every 12-18 months
When should levothyroxine be taken?
Before breakfast
What adjustments need to be made to levothyroxine in pregnancy?
Dose requirements may increase by 25-50% in pregnancy due to incresaed TBG
Who does myxoedema coma affect?
Typically affects elderly women with long standing but frequently unrecognized or untreated hypothyrodism
What are the common findigns in a myxoedema coma?
ECG: bradycardia, heart blocks, T wave inversion, prolonged QT
Type 2 resp failure: hypoxia, hypercarbia, resp acidosis
Co-exising adrenal failure
How is myxoedema coma treated?
ICU Passive rewarm Cardiac monitoring Monitor urine, fluid, CVP, surgars and oxygenation Broad spectrum antibiotics Thyroxine cautiousl
What is the difference between thyrotoxicosis and hyperthyroidism?
Thyrotoxicosis: clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid
Hyperthyroidism: refers specifically to conditions in which overactivity of the thyroid gland leads to thyrotoxicosis
What are the cardiac features of hyperthyroidism?
Tachycardia
Palpitation
AF
Cardiac failure (v rare)
What are the sympathetic symptoms of hyperthyroidism?
Tremor
Sweating
What are the CNS features of hyperthyroidism?
Anxiety
Nervousness
Irritability
Sleep disturbance
What are the GI features of hyperthyroidism?
Diarrhoea
What are the vision features of hyperthyroidism?
Lid retraction
Double vision (diplopia)
Proptosis (graves)
What are the hair and skin features of hyperthyroidism?
Brittle and thin hair
Rapid fingernail growth
What are the reproductive features of hyperthyroidism?
Menstrual cycle changes - lighter bleeding and less frequent
What are the metabolism features of hyperthyroidism?
Weight loss despite increased appetite
What are the thermogenesis features of hyperthyroidism?
Heat intolerance
What thyrotoxicosis causes are associated with hyperthyroidism?
Graves Thyroid nodules Hashitoxicosis Thyrotropinoma Thyroid cancer Choriocarcinoma
What thyrotoxicosis causes are not associated with hyperthyroidism?
Thyroid inflammation: Subacute (de Quervain's) thyroiditis Postpartum thyroiditis Drug-induced thyroiditis Exogenous thyroid hormones: over-treatment with levothyroxine Thyrotoxicosis factitia Ectopic thyroid tissue: Metastatic thyroid carcinoma Struma ovarii
What are the lab investigations of graves disease?
Decreased TSH and increased fT4/3
Hypercalcaemia
Increased alk phos
What antibody is commonly present in graves?
TSH receptor antibody
Anti-TPO
What clinical signs are specific to graves?
Pretibial myxoedema
Thyroid acropachy
Thyroid bruit
TED/ Graves opthamology
How is graves opthamology treated?
Mild: topical
Severe: steroids, radiotherapy, surgery
Who is likely to get nodular thyroid disease?
Older patients
What will nodular thyroid disease have biochemically?
Increased fT4/3 Decreased TSH Antibody negative Scintigraphy: high uptake Thyroid US
What is a thyroid storm?
Severe hyperthyroidism
What are the signs and symptoms of a thyroid storm?
Resp and cardiac collapse
Hyperthermia
Exaggerated reflexes
How is a thyroid storm treated?
Lugol's iodine Glucocorticoids PTU Beta blockers Fluids Monitoring
How does carbimazole work?
Inhibits TPO therefore blocking thyroid hormone synthesis
What is the first line drug in hyperthyroidism?
Carbimazole
What is the first line drug for hyperthyroidism in the 1st semester of pregnancy?
Propylthiouracil
How is graves treated?
Dose titrate for a year
OR
High dose for 6 months then treat with levothyroxine
What are the side effects of anti-thyroid drugs?
Allergic type - rash, urticaria, arthralgia
Cholestatic jaundice, deranged LFTs, fulminant hepatic failure
Agranulocytosis
What is agranulocytosis?
Bone marrow switches off the production of neutrophils
What is the advice given for a patient starting on ATDs?
Stop drug and have urgent FBC in event of fever, oral ulcer or oropharyngeal infection esp within first 6 weeks
When are beta blockers used in hyperthyroidism?
Immediate symptomatic relief of thyrotoxic symptoms
What beta blocker is used in hyperthyroidism?
Propranolol
Additionally inhibits DIO1
In what patients are beta blockers CI?
Asthma - use CCB (diltiazem) instead
When is radioiodine used in hyperthyroidism?
1st choice treatment for relapsed graves’ disease and nodular thyroid disease
Can radioiodine be used in pregnancy?
No
Can radioiodine be used in active thyroid eye disease?
Preferably no
When is a thyroidectomy utilised?
When radioiodine is CI or fails to work
What conditions fall under thyroiditis?
Hashimoto's De Quervain's (viral) Postpartum Drug induced (amiodarone, lithium) Radiation Acute suppurative thyroiditis
What are the associated symptoms with subacute thyroiditis?
Neck tenderness, fever or other viral symptoms
What is sick euthyroid syndrome?
Encountered in the unwell, hospitalised patient
Intercurrent infection has an impact on the HPT axis and TSH is typically suppressed and then rises during recovery
