Synopsis
Confirm excess circulating thyroid hormone, grade clinical urgency, distinguish increased synthesis from destructive or exogenous release, and begin safe cause-directed assessment.
- Thyrotoxicosis means tissue exposure to excess thyroid hormone; hyperthyroidism specifically means increased gland synthesis, so the terms are not interchangeable.
- Typical features include weight loss despite appetite, heat intolerance, sweating, tremor, anxiety, proximal weakness, frequent stools, menstrual change and tachycardia.
- Suppressed TSH with raised free T4 and/or free T3 confirms overt biochemical thyrotoxicosis after assay and medicine confounders are considered.
- Graves disease, toxic multinodular goitre and toxic adenoma produce hormone synthesis; subacute, painless or postpartum thyroiditis releases stored hormone; excess levothyroxine is exogenous.
- Examine pulse and rhythm, blood pressure, temperature, hydration, mental state, heart failure, muscle power, goitre or nodules, thyroid bruit and eye signs at the first encounter.
- NICE advises TSH-receptor antibodies to confirm Graves; if negative and the cause remains uncertain, consider technetium scintigraphy through the specialist pathway.
- Ultrasound is not a routine test for biochemical thyrotoxicosis and is mainly indicated when examination finds a palpable nodule or another structural concern.
- Before starting an antithyroid medicine, obtain full blood count and liver tests, discuss agranulocytosis symptoms, pregnancy and contraception, and check the current BNF.
- Antithyroid medicines do not treat destructive thyroiditis because new synthesis is already suppressed; symptom control and time are usually the core approach.
- Pregnancy or planned conception requires prompt specialist care because investigations, drug selection, dose targets and radioiodine eligibility change.
Key red flags
Atrial fibrillation, systolic hypertension, high-output failure, worsening angina or unexplained dyspnoea may dominate, especially in older people; establish haemodynamic stability before outpatient planning.
High fever, delirium, vomiting or diarrhoea, jaundice, marked tachyarrhythmia and cardiac failure indicate possible thyroid storm. Begin critical-care treatment on clinical suspicion without waiting for TRAb or imaging.
Investigation priorities
Confirm overt thyrotoxicosis and identify T3-predominant disease.
Management branches
A new thyroid profile or presentation suggests thyrotoxicosis.
- Perform ABCDE and document temperature, pulse rhythm, blood pressure, oxygenation, hydration, cognition, heart failure, chest pain and gastrointestinal or hepatic features.
- Escalate fever plus organ dysfunction, unstable arrhythmia, pulmonary oedema or delirium to the thyroid-storm and critical-care pathway immediately.
- If physiologically stable, obtain ECG and key bloods, assess pregnancy and arrange prompt endocrine or local pathway follow-up matched to severity.
Key medicines
Propranolol for adrenergic symptomsA common adult BNF range is 10 to 40 mg by mouth three or four times daily, adjusted to pulse, symptoms and comorbidity while the underlying cause is treated.Avoid or modify with asthma, significant bradycardia, heart block, hypotension or decompensated low-output failure. Pregnancy, older age and interacting rate-control therapy need individual review.
Carbimazole for hormone synthesisInitial adult dosing is severity-dependent and commonly totals 15 to 40 mg daily in the BNF; use the specialist plan, then reduce or block-and-replace only under the agreed protocol.Obtain baseline blood count and liver tests. Stop and seek urgent assessment for infection symptoms; discuss teratogenic risk, contraception, pregnancy, jaundice and pancreatitis, and follow current MHRA advice.