Third player
5-10% of thyrotoxicosis occurs with an increase in T3 only - without this test the diagnosis eludes. In hypothyroidism, T3 is not very informative (it falls last). Practical: take it according to a doctor’s indication if TSH is suppressed, and not “just in case” in a general check-up.
When is it appointed?
- fatigue, weight gain/loss, palpitations, hair loss - TSH screening;
- thyroid nodules - hormones + calcitonin;
- control of therapy with L-thyroxine and thyreostatics;
- pregnancy planning and pregnancy - mandatory TSH;
- autoimmune thyroiditis - antibodies.
Logic of thyroid tests
TSH is the main regulator and the most sensitive screening: the pituitary gland responds to the slightest changes in gland hormones. Free T4 and T3 clarify the severity of hypo-/hyperthyroidism, antibodies (AT-TPO, AT-TG) find an autoimmune cause, antibodies to TSH receptors confirm Graves' disease, calcitonin protects against medullary cancer in the nodes. Always start with TSH - the rest is according to indications, without unnecessary expenses.
