TSH-independent refers to a physiological or pathological state in which thyroid hormone production or activity occurs without regulation by thyroid-stimulating hormone (TSH) from the pituitary gland. This concept is clinically important because it explains conditions where thyroid function tests show abnormal hormone levels despite suppressed or low TSH, affecting diagnosis and management. A key example is autonomous thyroid nodules producing excess thyroid hormone independently, potentially causing thyrotoxicosis without elevated TSH.