Toxic Nodules are slow growing and difficult to diagnose
They take years for the abnormal DNA clone of to take over and first produce subclinical hyperthyroidism and even more years to recruit enough cells to make an elderly patient toxic. Even then because they do not look toxic like a Graves’ patient they can be missed a cardiac patient or broken hip osteoporosis patient without blood elevated TSH and T4. The term is apathetic hyperthyroidism. If the nodule is > 3 cm there is a 20% risk of thyrotoxicosis in the next 6 years.
Image from thyroid textbook of shows how a clone of cells are not seen at first and grow slowly to become a nodule and then suppress the TSH as subclinical hyperthyroid, and finally after many years into apathetic toxic nodule and a hot nodule suppressing the normal thyroid