What Should The Normal Creatinine Level Be In Case Of Chronic Kidney Disease?

My father is 73 years old , and is diaognised with chronic kidney disease . His serum creatinine for the last 2 years has been around 1.5 . However , in the recent test conducted 2 days ago , his serum creatinine has jumped to 1.9 which is markedly great in comparison to his last report 1 month ago which was 1.5 . He is on cardace 1.25 mg for the last 5 months having changed from losarton. I have heard cardace can cause renal impairment. Is my fear illfounded ?