The kidneys are paired organs in the lower back. They filter the blood to remove fluid, excessive chemicals and waste products; in the process they make urine. In addition, they regulate the mineral content of the blood and the acidity of the blood, help regulate blood pressure, make vitamin D and signal the bone marrow to make red blood cells among other functions. Many different diseases can damage the kidneys, and creatine is one indicator of kidney damage.
Causes of Kidney Disease
There are many different causes of kidney disease, and any of them can affect levels of different chemicals in the blood. Since the kidney has many blood vessels in order to filter the blood, diseases affecting the vessels, such as hypertension or high blood pressure can damage the kidneys. Trauma, such as falls, can also damage the kidneys. Infections and disorders in which the immune system attacks the kidneys are another source of kidney disease. Cancers can develop in the kidneys or spread to them from elsewhere in the body. There are many types of inherited and congenital, or "at birth," diseases as well. Various drugs and toxins can also damage the kidneys.
Creatine
Creatine is synthesized primarily in the liver and kidneys from amino acids, which are the building blocks of protein. It is then transported in the blood to the muscles. The muscles use creatine to help regenerate the energy needed for contraction. Muscle cells use the chemical adenosine triphosphate or ATP to supply energy. Once the ATP is used, creatine can be used to regenerate it. As such, creatine acts as a backup supply of energy.
Creatine Levels and Kidney Function
Creatine is also filtered in the blood and disposed of in urine. As such, diseases of the kidneys that interfere with kidney function increase the levels of creatine in the blood. Elevated creatine is a marker of kidney function.
Classifications of Renal Insufficiency
Elevated creatine ultimately comes from decreased filtration of the blood by the kidneys, called renal insufficiency. There are three general ways in which this can happen. The first, called prerenal insufficiency, results when not enough blood reaches the kidneys. This can happen in dehydration or blood loss, for example. Intrarenal insufficiency refers to damage to the kidneys, as from infections, tumors or high blood pressure. Postrenal insufficiency refers to problems in the urinary system after the kidneys, such as the ureters leading to the urinary bladder, that interferes with blood filtration. An example is a kidney stone blocking a ureter, causing urine to back up into the kidney.
References
- "Physiology"; Linda Costanzo; 2009
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al.; 2008
- "Robbins and Cotran Pathologic Basis of Disease" Vinay Kumar et al.; 2009
