Found in the blood, it is a waste by-product of muscle; creatinine level in the blood is one of the key measures of kidney function. (HRSA/OPTN Patient Glossary, June 2026)
A waste product that your kidneys filter out of your blood. Some creatinine in the blood is normal, but too much can be a sign that there is a problem with your kidneys. (AST Glossary, June 2026)