Pathogenesis (disease development)
In latent (subclinical) hyperthyroidism, there is mild dysfunction of the thyroid gland. The thyroid hormones fT3 and fT4 are present in the blood at normal concentrations, whereas TSH (thyroid-stimulating hormone) is <0.3 mU/l.
Etiology (Causes)
Biographic causes
- Genetic burden – TSH receptor mutations.
- Hormonal factors
- Mutations of the TSH receptors
- Thyroid hormone resistance
Disease-related causes
- Autoimmune thyroiditis (AIT) – autoimmune disease of the thyroid gland; initially with increased secretion of thyroid hormones, later with gradual transition to hypothyroidism (hypothyroidism).
- Graves’ disease – form of hyperthyroidism.
- Thyroid autonomy – a growth of the thyroid gland and hormone production independent of physical influences.
Medication
- Iodine-containing contrast mediaNote: Contraindicated in manifest hyperthyroidism (absolute avoidance); in latent (subclinical) hyperthyroidism, use of iodine-containing contrast media only under thyrostatic protection (perchlorate and thiamazole shortly before the examination and 2 weeks afterward, so that iodine uptake by the thyroid gland is no longer possible).
- Iodine excess
- Thyroid hormones – medications such as L-thyroxine, which is used to treat hypothyroidism (underactive thyroid), after thyroid surgery, or Graves’ disease, among other conditions
Radiotherapy
- Radioiodine therapy – therapy of hyperthyroidism or thyroid carcinoma with radioactive substances.
Other causes
- Pregnancy-associated hyperthyroidism
