Is Cystatin C a Marker of Glomerular Filtration Rate in Thyroid Dysfunction?

In the recent literature, cystatin C has been advocated as a new and more accurate estimate of glomerular filtration rate (GFR) (1). Cystatin C is a 13-kDa endogenous cysteine proteinase inhibitor produced by all nucleated cells at a constant rate and broken down completely in the renal tubuli (2). Cystatin C concentrations are independent of age and body weight, and there is no need for urine collection for clearance estimations. Furthermore,...