Endocrine - Thyroid Flashcards
What are the clinical features of hyperthyroidism?
- Temperature intolerance
- Appetite changes
- Weight changes
- Bowel habit changes
- Changes in sympathetic discharge
- Changes in skin and nails
- Changes in mood
- Eye problems
- Other systemic signs
Heat intolerance
Polyphagia (↑Appetite)
Weight loss
Diarrhoea, increased bowel movements
Increased sweating, Palpitations
Dry, scaly skin, Onycholysis (Graves’)
Changes in mood
- Nervousness, Insomnia
- Irritability
- Hyperactivity
Eye problems
- Double vision
- Redness
- Pain
Other systemic signs
- Muscle weakness: cannot climb stairs, comb hair
- Exertional dyspnoea: CCF
- Insomnia
- Pretibial Myxoedema (only in grave’s)
- Amenorrhea
What are the clinical features of hyporthyroidism?
- Temperature intolerance
- Appetite changes
- Weight changes
- Bowel habit changes
- Changes in sympathetic discharge
- Changes in skin and nails
- Changes in mood
- Eye problems
- Other systemic signs
Cold intolerance
Decreased appetite
Weight gain
Constipation
Lethargy
Coarse, pale, dry
Xanthoma (hyperlipidemia)
Changes in mood
- Mental, physical sluggishness
- Depression
- Poor memory
Eye problems
- Odema of eyelids
- Xanthalesma (hyperlipidemia)
Other systemic signs
- Hoarse voice
- Hypercarotenamia
- Leg swelling (myxoedema)
- Menorrhagia
What are causes of goitre + hyperthyroidism?
Grave’s, Benign Thyroid neoplasms
What are causes of goitre + hypothyroidism?
Hashimoto’s Thyroiditis, Iodine Deficiency (thyroid compensates by enlarging to increased iodine uptake), De Quervain’s Thyroiditis (subacute thyroiditis)
What are the thyroid eye signs?
Bulging eyes (exopthalmos) 🡪also causing Pain, Inability to close eyelids
Upper eyelid retraction: you can see the upper limbus which is ABNORMAL
Lid lag on downward gaze: due to retraction
Conjunctivitis
Ophthalmoplegia: Affects in order Inferior R 🡪 Medial R 🡪 Superior R 🡪 Lateral R
Diplopia – due to swollen extraocular muscles, ask esp when looking down
Vision Changes – due to compression on optic nerve
What are the complications of hyperthyroidism?
Compression (usually if malignant): Stridor / Dyspnoea, dysphagia, syncope
Invasive (for thyroid cancer)
Signs of heart failure & A Fib: due to hyperthyroid
Recent fragility fractures from osteoporosis due to Hyperthyroidism
What are the causes of hyperthyroidism?
Grave’s disease
Toxic multinodular goiter/ toxic adenoma
Thyrotoxic phase of Hashimoto’s or postpartum thyroiditis
Thyrotoxic phase of Subacute (de Quervain) granulomatous thyroiditis – preceding URTI
Subacute lymphocytic thyroiditis
Exogenous
Pregnancy (hCG)
Testicular germ cell tumour (hCG)
Hydatidiform mole/ choriocarcinoma (hCG)
What are the causes of hypohyroidism?
Autoimmune thyroiditis
- Hashimoto’s
- Postpartum
- Riedel (IgG4 secreting plasma cells)
- Atrophic (no goiter)
Drugs
- Carbamazepine
- Lithium: “any mood drugs?”
- Amiodarone
- Phenytoin
Iodine deficiency e.g. in pregnancy
Dyshormonogenesis
Subacute (de Quervain) thyroiditis
What are the differentials for a solitary nodule of a thyroid mass?
- Dominant nodule of MNG
- Follicular adenoma
- cyst
- carcinoma
What are the differentials for a thyroid mass that is diffusely enlarged?
Hyperthyroid: Graves
Non toxic (hypothyroid/ euthyroid): lymphoma, Hashimoto’s thyroiditis, subacute thyroiditis
What are the differentials for a multinodular goitre?
Hyperthyroid: toxic MNG
Hypothyroid: Hashimoto’s thyroiditis
How do you approach a thyroid nodule?
1) Examine Thyroid Status 🡪 Thyroid function test to assess fT4, TSH
- To assess if nodule is a/w HyperT, HypoT, EuT (not necessarily causing it)
- Majority of pt with thyroid nodules are euthyroid!
2) Examine the Nodule 🡪 Thyroid USS; more likely Malignant if:
- Tall & Thin on transverse scan
- Increased internal vascularity (via doppler US)
- Irregular Edges
If diffusely enlarged 🡪 confirm w/ USS 🡪 proceed w/ Auto-Ab testing
If nodule 🡪 proceed with step
3) Iodine Uptake Scan 🡪 to assess if Hot or Cold Nodule!
- Hot Nodule aka a TOXIC nodule causing massive fT4 release (and hence low TSH). Does NOT require Biopsy, toxic thyroid nodules tend to be indolent and less aggressive
- Cold Nodule: Nodule is inactive and does not produce T4. Require biopsy to determine if nodule is Thyroid / secondary tumor! If pt with cold nodule is hyperT 🡪 may indicate a separate aetiology
4) Biopsy via FNAC: Bethesda Classification
What is the treatment of hot thyroid nodule?
Treat with uni/bilateral Thyroidectomy OR Radioactive Iodine treatment
Radioactive Iodine treatment may leave pt Hypothyroid for the rest of his life, requiring Thyroxine supplementation
What are the investigations performed for hyperthyroidism/ hypothyroidisim?
Thyroid panel
- Thyroid stimulating hormone
- Free Thyroxine (T4)
Antibodies
- Graves’: TRAb (TSH Receptor Ab) / TSI (Thyroid Stimulating Immunoglobulins)
- Hashimoto’s: TPO Ab (Thyroid Peroxidase Ab) / TG Ab (Thyroglobulin Ab)
US thyroid – to assess nodularity / diffuse swelling. Not required to Dx grave’s if there is PE findings & +ve Ab
Radioiodine uptake scan – more so for nodules to assess if hot / cold
FNAC
What is the treatment of hyperthyroidism?
Symptom control
- Beta-blockers i.e. atenolol 25-50mg/day
- Alternative to BB: CCB (eg: Diltiazem)
Anti-thyroid Medication (thionamides) 🡪 inhibits thyroid hormone synthesis
- E.g. Carbimazole, Propylthiouracil (PTU) 🡪 Block & Replace approach
Radioiodine (RAI): Will need Lifelong thyroid hormone replacement
Surgical aka thyroidectomy: partial or total (w/ thyroxine replacement)
What are the side effects to Anti-thyroid Medication (thionamides)?
Agranulocytosis (0.5%), cross-reactivity between 2 drugs
- Emphasis on the importance of regular blood tests
- Advise if fever/sore throat/mouth ulcers to stop, check WCC
Propylthiouracil preferred in pregnancy (T1) as carbimazole is teratogenic (C/I in T1)
Hepatotoxicity: Carbimazole less hepatotoxic, longer half-life
What is the counselling required for Radioiodine?
Will need Lifelong thyroid hormone replacement
Contraindicated in breastfeeding / pregnancy and avoid for 6M to 1Y
Thyroid Eye Disease is a RELATIVE CONTRAINDICATION – RAI will worsen the eye disease; however we can provide steroids to prevent this
Ask if staying at home w/ pregnancy women / young children 🡪 radiation exposure through contact / urine is bad for them. Cannot hug them, cannot even share the same toilet
What are the indications of thyroidectomy: partial or total (w/ thyroxine replacement)?
Relapse despite pharmacological therapy
Cosmesis
Development of thyroid eye signs, compressive symptoms : 1st line for pt w/ TED is Surgery, however RAI is still possible w/ steroids if Surgery is C/I
Cancer
What are the risks of thyroidectomy?
Damage to parathyroids: may lead to transient hypocalcaemia
Recurrent laryngeal N injury 🡪 hoarseness of voice
Life-long thyroxine
What are the clinical features of thyroid storm?
- Pyrexia (Fever): very severe if >40 degrees
- Tachycardia
- Neurological Dysfunction (Restlessness -> Agitation -> Psychosis -> Seizures -> Coma)
- Cardiovascular Dysfunction (A Fib, Heart Failure)
- GI Dysfunction (N&V, Diarrhoea, Abdominal Pain, Jaundice)
What is the Burch- Wartosky score?
Components (same as the characteristic clinical features)
- Thermoregulatory
- CNS: mental state
- GI
- CVS (Tachycardia, AF)
- CCF
Interpretation of score!
- 45 and above = highly suggestive
- 25-44 = supports
- <25 = unlikely thyroid stor
What are the precipitants of a thyroid storm?
- Infection (Most Common)
- Infarction / CVA / CCF / DKA / Trauma
- Recent thyroid surgery
- Radioiodine Therapy (RAI)
- Non-Thyroid Sx in pt w/ inadequately controlled HyperT or undiagnosed HyperT
- Sudden withdrawal of antithyroid medication
- Administration of iodinated contrast
What are the investigations to be performed for thyroid storm?
ABCs
Bloods
- FBC, Renal Panel, LFT, FT4, TSH, CBG
- Septic Workup (a DDx for thyroid storm + to elucidate aetiology for thyroid storm)
Imaging
ECG – for AMI
CXR – for CCF
What is the management of a thyroid storm?
Beta-blocker if patient in severe tachycardia (>170 bpm will compromise CO): Propanolol 40-80mg 6-8 hourly or Esmolol (faster acting + cardioselective 😊)
Inhibition of new thyroid hormone synthesis: PTU 400-600mg stat then 200mg 4-6H or Carbimazole 30mg BD-QDS
- However PTU has S/E of hepatotoxicity (will worsen the liver damage in Thyroid Storm)+ CMZ is faster acting, hence CMZ the preferred choice
Inhibition of thyroid hormone release (after inhibiting synthesis)
- Lugol’s iodine 4-8 drops 6-8hourly (Wolff-Chaikoff effect)
- Given 1 hour after CMZ – if given before, iodine may be used by thyroid to produce more thyroid hormones
Inhibition of peripheral T4 to T3 conversion: Steroids i.e. IV hydrocortisone 50-100mg 6-8H for 24-36 hours
Removal of excess thyroid hormones : Cholestyramine – removal through enterohepatic circulation
Treat the underlying trigger
