In most cases, serum creatinine can reflect the degree how kidney is damaged. In the third stage of kidney disease, the creatinine in serum can be as high as 186-442umol/L.Creatinine is really an important reference in many countries. In China, renal insufficiency can be divided into 4 stages according to serum creatinine, which are compensation stage, discompensation stage, early stage of renal failure and advanced stage of renal failure.