Creatinine tests measure the level of the waste product creatinine in the blood. These tests indicate how well your kidneys are working. Creatine is formed when we digest our food. Creatine is broken down into another substance known as creatinine, which is removed from the blood via the kidneys and then passes out of the body in the urine. If your kidneys are damaged and are unable to work normally, the creatinine level in the urine is reduced and the level in the blood is increased. That blood creatinine level shows how well your kidneys are working. A high creatinine level may indicate that your kidneys are not working properly. The amount of creatinine in the blood is partly dependent on how much muscle mass you have. Men generally have higher creatinine levels than women.
A blood creatinine level test is carried out to see whether your kidneys are working normally, and how well the kidneys are working in people taking medications that can cause kidney damage.
High levels are seen in cases of reduced glomerular infiltration; pre-renally in cases of circulatory failure, renally when the glomerulus is damaged, and post-renally when the outflow is obstructed.
Low levels have little clinical significance. Present in pregnancy and patients with atrophic muscles.