Acute kidney failure refers to the sudden development of worsening kidney function, typically in reference to the kidney's failing ability to regulate the body's electrolytes, acid/base balance, overall fluid level, and excretion of waste via the production of urine. Usually acute kidney failure is diagnosed with a combination of blood and urine tests. Blood tests are normally used to measure the serum creatinine, which is a commonly used marker of the ability of the kidney to filter waste products from the blood; the higher the creatinine, the worse the kidney function.
Blood is also used to measure electrolytes and acid levels; acid may build up in kidney failure, and electrolyte derangements such as high potassium may occur. Urine production may decrease in acute failure, and additional blood and urine tests can be performed to help diagnose the underlying cause of the kidney failure. If these tests are unrevealing, then kidney biopsy
may need to be performed to make an accurate diagnosis. The use of imaging with x-ray
and CT scanning does not make up the foundation of determining kidney function; it may be used in some cases to help identify a cause (such as obstruction of the bladder or ureters) but usually ultrasound
can help make this diagnosis and spare the use of radiation.