When the kidneys arena working properly then the blood levels of creatinine increase; hence creatinine is just a marker of renal dysfunction. The normal levels of serum creatinine varies between laboratories but are usually between 0.8-1.2mg/dI for adults.

A more accurate way of assessing renal function is to calculate the GFR (Glomerular Filtration Rate). When both kidneys work properly the GFR readings are in the range gf 100m1/min, which is 100% efficiency. When GFR drops below 50 ml/min, early problem like anaemia start; symptoms of uraemia start when GFR drops below 20m1/min. Dialysis is required when the GFR is 15m1/min. or below.