Thyrotoxicosis



Background

Thyrotoxicosis causes

  • Commonest is Graves disease (auto Ab to TSH receptor with XS T4 and reduced TSH from pituitary)
  • Thyroid adenoma (or rarely carcinoma)
  • Toxic multi-nodular goitre
  • TRH producing pituitary adenoma
  • Iodine or amiodarone administration.
  • 1% of thyrotoxic pushed by trigger (AMI, meds change, sepsis, surgery etc.) into thyroid storm (30 - 60yo)

Differential Dx


Thyroid storm

  • Life threatening hyper-metabolic state
  • Clinical Dx
  • Wt loss, tachyarrhythmias, alopecia, eye abnormalities etc
  • Hyper-metabolic state (pyrexia, hypertension, tachycardia [AF], tachypnoea, CCF, eye signs, hyperglycaemia)
  • Low TSH, high T3 T4
  • Look for precipitating cause (particularly sepsis)
  • Beware CCF (arrhythmia, persistent hypertension, cardiomyopathy)

Management thyrotoxicosis / storm

  • Target each T4 synthesis step
  • Propylthiouracil (PTU) (inhibits hormone synthesis and T4 to T3 conversion).
  • Propanolol (inhibits target organ effects and inhibits conversion T4 to T3)
  • Iodine (inhibits T4 release from gland: but never unless PTU already given as may stimulate T4 release)
  • Consider steroids (any signs of Addison’s?)
  • Consider paracetamol for pyrexia etc.
  • Avoid Aspirin (unbinds T4 from plasma proteins)
  • Avoid amiodarone (self explanatory)
  • ACEI or diuretics usually safe if required (CCF)
  • Anticoagulation if in atrial fibrillation

Content by Dr Íomhar O' Sullivan 04/02/2011. Last review Dr ÍOS 4/12/18.