Sixty year old man has 1. 9 Mg/Dl creatine level. Is it a serious condition?

My father, above sixty years old . He has 1. 9 Mg/Dl creatine level. Is it a serious condition… What to do immediately… As a part of severe fever he showed the increase in creatin level… After that there was a decrease in creatin level…. But know it became 1. 9. After the abdominal scan doctor told us there is no problem for kidney…. Iam really tensed. What to do doctor