What does subclinical hyperthyroidism mean?

Subclinical hyperthyroidism refers to the absence of clinical symptoms, or symptoms are not specific, although the serum thyroid stimulating hormone (TSH) level is lower than the lower limit of the reference range, or can not be measured, and the serum free thyroxine (FT4), free triiodothyronine (FT3) levels are normal, but in fact the thyroid gland is in a state of hyperfunction. Subclinical hyperthyroidism may be caused by recent stress, infection levels, drug effects, etc.With the elimination of these factors, thyroid function may return to normal, which is temporary. However, subclinical hyperthyroidism may persist in some patients and may even progress to clinical hyperthyroidism. Sustained subclinical hyperthyroidism requires close attention and regular monitoring to assess trends and potential effects on the body. Subclinical hyperthyroidism may increase the risk of cardiovascular disease, such as arrhythmia levels, hypertension levels, etc... even in the absence of overt hyperthyroidism symptoms. Long-term mildly elevated thyroid hormone levels may lead to increased cardiac load and increased myocardial oxygen consumption, which may affect normal cardiac function. This effect may be more pronounced in the elderly and patients with pre-existing cardiovascular disease, which requires special attention. Subclinical hyperthyroidism cannot be diagnosed by a single thyroid function test, but needs to be confirmed by multiple re-tests. At the same time, it is necessary to make a comprehensive evaluation in combination with the patient's medical history, symptoms levels, signs and other relevant examinations. For example, it is necessary to rule out other possible causes of TSH decrease, such as pituitary disease. In addition, for patients with questionable diagnosis, thyroid iodine uptake rate and other examinations may be performed if necessary to further confirm the diagnosis.