This is renal failure characterized by sudden drop in urinary output and the steady increase of serum urea nitrogen and creatinine levels. Common causes of ATN are hypotension, sepsis, burns, and eclampsia. The urine specific gravity is 1.010 or less (loss of ability to concentrate). In the recovery phase, high output failure (low specific gravity, large volume, and lack of ability to excrete nitrogen or potassium) is often the case.