Table 1.

Causes of thyrotoxicosis

Thyrotoxicosis associated with hyperthyroidism
Aetiologies (common)Mechanism
Graves’ diseaseThyrotropin receptor antibodies stimulate the thyroid-stimulating hormone (TSH) receptor
Toxic multinodular goitreActivating mutations in TSH receptor or G proteins
Solitary toxic adenomaFunctional autonomy within a benign lesion
Aetiologies (uncommon)Mechanism
TSH secreting pituitary adenomaPituitary adenoma
Pituitary resistance to thyroid hormoneMutation of thyroid hormone receptor β
Neonatal Graves’ diseaseThyroid stimulating immunoglobulins
ChoriocarcinomaHuman chorionic gonadotropin
Hyperemesis gravidarumHuman chorionic gonadotropin
Congenital hyperthyroidismActivating mutations in TSH receptor
Struma ovariiToxic adenoma within dermoid tumour of the ovary
Metastatic follicular thyroid carcinomaFoci of functional autonomy
Iodine or iodine containing drugsJod-Basedow phenomenon; excess iodine results in unregulated thyroid hormone production
Thyrotoxicosis not associated with hyperthyroidism
Aetiologies (common)Mechanism
Thyroiditis Painless including postpartumAutoimmune, release of stored thyroid hormones
Sub-acute thyroiditisViral infection, release of stored thyroid hormones
Exogenous thyroid hormoneIatrogenic or factitious excess ingestion of thyroid hormone
Aetiologies (uncommon)Mechanism
Drug induced thyroiditisDestruction of thyroid follicles
Acute infectious thyroiditisBacterial or fungal thyroid infection
Radiation induced thyroiditisRadioactive iodine induced thyrocyte destruction
Thyroid adenoma infarctionRelease of stored hormones