Relatively normal glomerular filtration rate — Urinary losses of thyroxine (T4) - binding globulin (TBG) and other thyroid hormone-binding proteins (transthyretin and albumin) and the T4 bound to them result in a low total T4 concentrations in approximately 50 percent of nephrotic patients with a relatively normal glomerular filtration rate (GFR) [5 - 7].