[Acute and chronic renal insufficiency. Diagnostics and practical implications].

A newly diagnosed renal insufficiency should be investigated thoroughly, since even slight elevations of renal retention parameters reflect a relevant loss of renal function. Acute creatinine elevations above 0.3 mg/dl are considered an acute kidney injury. Renal failure can be classified according to different criteria. Generally, an acute kidney injury should be separated from chronic renal failure leading to different diagnostic and therapeutic consequences. In most cases, some easy procedures (history, ultrasound, blood tests) help to differentiate between acute and chronic failure. While adequate therapy results in restitution of acute kidney injury in most cases, the aim in chronic renal failure is to minimize complications and to delay renal replacement therapy. Therefore, it is mandatory to involve renal specialists as it has been shown that early referral to nephrologists can ameliorate renal morbidity and mortality. Except for postrenal causes of renal deterioration the diagnostic and therapeutic work-up should be done by nephrologists to avoid unnecessary complications and expenses.