Second stage
The TSH + fT4 pair covers 95% of thyroid diagnosis: subclinical hypothyroidism (TSH↑, T4 normal) is often observed, manifest hypothyroidism (both shifted) is treated. The free fraction does not depend on carrier proteins and is correct during pregnancy and estrogen intake, unlike total T4.
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.
