Creatinineis a waste product in your blood that comes from the digestion of protein in your food and the normal breakdown of muscle tissue. It is removed from your body through the kidneys. If you have kidney disease, the kidneys can have trouble removing creatinine from your blood. So, the level of creatinine in your blood starts to go up. High creatinine levels can be a sign ofacute kidney injuryand/orchronic kidney disease. A “normal” creatinine level in the blood is hard to define because it can change depending on your age, sex, body size, and other factors.
Cystatin C
Cystatin C is a protein that is produced by the cells in your body.