Search for New Methods to Detect Acute Renal Failure

The purpose of this study is to find substances in the blood and urine that indicate that a person has kidney damage. It will identify proteins found only in patients with acute kidney failure but not in normal healthy people or in patients with volume depletion. Adults and children who are at least 3 years old who fall into one of the following four categories may be eligible for this study: 1. Are healthy and have normal kidney function 2. Have volume depletion (this condition differs from acute kidney failure in that it is easily treated with fluids) 3. Are at high risk of kidney failure 4. Have acute kidney failure (kidney shutdown) All study participants will have a history and physical examination. Up to four blood samples of 3 tablespoons each will be taken for laboratory analysis. Urine will be collected for analysis and to measure urine output. The participants length of stay in the study varies. People with normal kidney function will be in the study for 1 day and patients with volume depletion will be studied 3 days. The length of hospitalization of patients at high risk of kidney failure or in acute kidney failure will depend on the patient s condition and medication requirements. The results of this study may lead to the development of earlier and more accurate methods for diagnosing acute kidney failure. With earlier detection, treatment could be started earlier, possibly preventing further damage and helping recovery of injury that has already occurred.