AKT · Endocrine/Thyroid

Hyperthyroidism / thyrotoxicosis

Thyroid hormone excess (Graves, toxic nodular, thyroiditis)

Overview

Excess thyroid hormone, most often Graves' disease (autoimmune TSH-receptor stimulation), toxic multinodular goitre/adenoma, or thyroiditis. Hypermetabolic features — weight loss, heat intolerance, tremor, palpitations. Beta-blockade controls symptoms; carbimazole/PTU, radioiodine or surgery are definitive. Radioiodine uptake distinguishes the cause.

Recognise

Weight loss with increased appetite, heat intolerance, sweating, tremor, palpitations, anxiety, diarrhoea, oligomenorrhoea
Tachycardia/AF, fine tremor, warm moist skin, lid lag; goitre; Graves-specific: eye signs (proptosis/lid retraction), pretibial myxoedema, thyroid acropachy
Biochemistry: low TSH with high free T4/T3

Red flags

Thyroid storm (fever, agitation, tachyarrhythmia, delirium, often precipitated by illness/surgery) → emergency
New AF → anticoagulation assessment; severe Graves orbitopathy (reduced vision/colour) → urgent ophthalmology

Differentials & how to tell them apart

Graves diseasediffuse goitre + eye signs + TRAb positive + diffuse uptake

Toxic multinodular goitre / adenomanodular gland, older patient, 'hot' nodule(s) on scan, no eye signs

Thyroiditis (subacute/postpartum)tender goitre (De Quervain) or postpartum; LOW radioiodine uptake; transient, self-limiting → beta-blocker only

Factitious / amiodarone-inducedexogenous thyroxine (low thyroglobulin) or amiodarone (type 1 vs 2)

Investigations

TFTs: ↓TSH, ↑free T4/T3. TSH-receptor antibodies (Graves). Radioiodine/technetium uptake: diffuse (Graves), hot nodule(s) (toxic nodular), low uptake (thyroiditis).

Management

Beta-blocker for symptoms + carbimazole (then radioiodine/surgery as definitive)

1Beta-blocker for adrenergic symptoms while arranging endocrinology. Antithyroid drug (carbimazole) — 'titration' or 'block-and-replace'. Distinguish the cause with TRAb/uptake scan because thyroiditis needs only a beta-blocker.Gate: Carbimazole risks AGRANULOCYTOSIS — warn to seek an urgent FBC for sore throat/fever/mouth ulcers; in the FIRST TRIMESTER use PTU (carbimazole is teratogenic); avoid radioiodine in active Graves ORBITOPATHY or pregnancy
2Definitive treatment: radioiodine or thyroidectomy (then lifelong levothyroxine); treat AF/anticoagulation; manage orbitopathy (cross-ref ophthalmology); thyroid storm → emergency (beta-blocker, PTU, iodine, steroids).

Beta-blocker (propranolol) — rapid symptom control (palpitations, tremor); bridge while awaiting definitive treatment

Carbimazole — antithyroid — first-line; risk of AGRANULOCYTOSIS (warn re sore throat/fever → urgent FBC); teratogenic in 1st trimester

Propylthiouracil (PTU) — first trimester of pregnancy and thyroid storm; small hepatotoxicity risk

Radioiodine / thyroidectomy — definitive; radioiodine avoided in active orbitopathy/pregnancy

Key points

Low TSH + high T4 = thyrotoxicosis; the uptake scan sorts Graves (diffuse) from toxic nodular (hot nodule) from thyroiditis (low uptake — beta-blocker only). Remember the two carbimazole gates: agranulocytosis warning and PTU in early pregnancy.

Monitor & prognosis

TFTs during titration; FBC if infection on carbimazole; post-ablation hypothyroidism.

Good; many become hypothyroid after definitive treatment.

Source: NICE NG145/CKS Hyperthyroidism