Creatinine

Creatinine is a breakdown product of Creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass). It is a chemical waste molecule that is generated from muscle metabolism.

Serum creatinine (a blood measurement) is an important indicator of renal health because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys.

The kidneys maintain the blood creatinine in a normal range. Creatinine has been found to be a fairly reliable indicator of kidney function. Elevated creatinine level signifies impaired kidney function or kidney disease.

As the kidneys become impaired for any reason, the creatinine level in the blood will rise due to poor clearance of creatinine by the kidneys. Abnormally high levels of creatinine thus warn of possible malfunction or failure of the kidneys. It is for this reason that standard blood tests routinely check the amount of creatinine in the blood.

Fun facts:

• Creatinine is produced from Creatine, a molecule of major importance for energy production in muscles.
• Approximately 2% of the body's creatine is converted to creatinine every day.
• Creatinine is transported through the bloodstream to the kidneys. The kidneys filter out most of the creatinine and dispose of it in the urine.
• Because the muscle mass in the body is relatively constant from day to day, the creatinine production normally remains essentially unchanged on a daily basis.