What does Creatinine 1.6 Mean?

What does creatinine 1.6 mean? When some people go to have a yearly physical examination in a hospital, the report may say that the creatinine in serum is out of normal range and has increased to 1.6, which shows that there is something wrong in the kidney. Why? What is creatinine and what is the normal range of creatinine and what does creatinine 1.6 mean?
Firstly, creatinine is a metablic product of muscles which should be discharged out of the body and generally, 20g muscle can make 1g creatinine. Creatinine level in the serum can also be influenced by food we take in, exercise we take and other factors such as decreased renal function.
Kidney has one important function which is to discharge toxins which is produced in the body such as creatinine. So when kidney is damaged, the level of creatinine is serum will increase and accordingly, the level of creatinine in urine will become less, which should be more than that in serum in normal condition.
Secondly, in normal condition, the serum creatinine is 0.5 to 1.2. And here we should point out is that there are a little differences in different labs.
Thirdly, creatinine 1.6 means that patients have become renal failure stage and should take effective measures as soon as possible.