Hyperthyroidism (Thyrotoxicosis)

Incidence 1 in 2000 in Europe

Thyrotoxicosis is confirmed by either raised T4 or T3 or both with a suppressed TSH

Click here for causes


Red flags

  • Thyroid storm- admit as medical emergency
  • Suspected thyroid malignancy – refer on 2ww head and neck pathway



  • Overt hyperthyroidism  ( Routine Endocrinology)
  • Amiodarone induced hyperthyroidism ( Urgent Endocrinology)
  • Persistent subclinical hyperthyroidism ( see below) (Routine Endocrinology)
  • Hyperthyroidism whilst pregnant ( Urgent joint Endocrinology/antenatal clinic)
  • Do not start treatment  in primary care if pregnant

 Pending appointment, if the GP has specific concerns or clinical / biochemical deterioration please use Endocrine A&G for advice.


If Subclinical hyperthyroidism ( low TSH with normal fT4, fT3):

  • Assess for clinical features of hyperthyroidism
  • Assess for other causes of low TSH
  • Non thyroid illness
  • Drugs-supressing TSH: glucocorticoids, dopaminergic [anti-parkinsonian] medication, or octreotide)
  • Drugs that alter thyroid hormone secretion (lithium, amiodarone, and iodide in contrast media dyes)


  • If other causes excluded, initially rpt TFTS in 3-6months ( sooner if elderly or cardiovascular disease) and refer if persistent
  • If untreated subclinical hyperthyroidism, continue to check TFTS 6-12monthly


Investigations– pre referral:


·         Request TSH, T4, T3, TSH receptor antibodies (please note the lab will however only check T3 if T4 is normal/ near normal)

·         Pregnancy test if appropriate

o   If pregnant request TSH receptor antibodies as well

Please do NOT:

·         request an USS

·         request a radionuclide uptake scan 


Primary care treatment - whilst awaiting specialist assessment

  • Consider B-Blocker (if no contraindications), if tremor or tachycardia ( propranolol  up to 20mg tds)
  • Check U&E, FBC for baseline levels prior to starting antithyroid drugs
  • Consider carbimazole (seek specialist advice via Endocrine A&G prior to starting) 
  • If the patient plans to get pregnant in the next 6 months please use propylthiouracil as opposed to carbimazole.











 Counsel patients of the risk of agranulocytosis and what are the warning symptoms and signs.

Please repeat TFTs every month and adjust carbimazole dose accordingly until seen in clinic

  • Atrial fibrillation – anticoagulate and rate control as per RMS guidance / cardiology / AF

Patient resources:

British Thyroid foundation, www.btf-thyroid.org

Thyroid UK, www.thyroiduk.org.uk



CKS NICE Hyperthyroidism

Personal communication with Duncan Browne, Consultant Endocrinologist, RCHT


Date Reviewed            20/09/2021

Next Review Date       20/09/2022

Author                         Dr B Wesson ( RMS GP Endocrinology lead)

Contributor                  Duncan Browne, Consultant Endocrinologist RCHT


Version No.                  3.1