Why not just use the s-creatinine or s-urea?
The relationship between s-creatinine and GFR is not linear. Thus, large changes in renal function are reflected by small changes in s-creatinine. In fact, s-creatinine will detect changes in renal function only after the GFR has declined by 50%. In addition, because s-creatinine is influenced by age and muscle mass, a set of at least 10 separate reference intervals would be required to accurately define normal adult function.
The relationship between s-creatinine and GFR is not linear. Thus, large changes in renal function are reflected by small changes in s-creatinine. In fact, s-creatinine will detect changes in renal function only after the GFR has declined by 50%. In addition, because s-creatinine is influenced by age and muscle mass, a set of at least 10 separate reference intervals would be required to accurately define normal adult function. S-urea is influenced significantly by hydration and protein intake and is a less accurate indicator of glomerular function than s-creatinine.
