[Management of acute renal failure in hospital practice]

The incidence of ARF in pediatric population varies according to the definition of the syndrome. If the diagnosis is based on a decrease of glomerular filtration rate (GFR), possibly accompanied by a decrease of urinary output and the sudden change of renal function indexes, then the number of patients which can be considered affected by ARF in hospital practice is high, as it comprises all the cases with functional impairment of renal function. The availability of tables with normal values of serum creatinine for different gender and age and the knowledge of the minimal urine output compatible with the normality allows a precise diagnosis of ARF. The differential diagnosis of ARF must take into account prerenal, renal and postrenal causes. Prerenal and renal ARF may be sometimes difficult to differentiate. Indexes such as sodium fractional excretion, utilizing urinary to plasma ratios of sodium and creatinine, can be helpful: values less than 1 indicate prerenal ARF, more than 2 renal ARF. The management of ARF is dependent on the causes of ARF. Prerenal ARF is normally treated by measures of volume expansion and/or removal of the underlying cause. Renal ARF requires an accurate control of water and electrolyte balance and of nutritional status and the prevention or treatment of numerous complications, which may worsen the course of the syndrome. Indications to dialysis must be evaluated every day and an assessment of nutritional status performed. All the factors which may cause hypercatabolism, such as infections, hemorrhage, low calorie intake, must be recognized and treated. This approach allows a better control of serum urea, potassium, phosphate and acidosis. Nutrition must be implemented and an adequate protein and calorie intake must be obtained, through spontaneous oral route and, whenever required, enteral and parenteral nutrition. In conclusion, patients with mild-degree, mostly of prerenal origin, ARF represent a common finding in hospital practice. Identification and prompt treatment of the underlying cause is the best prevention of acute tubular necrosis. Patients with ARF of renal origin require, in particular, daily nutritional assessment and dietary treatment to delay the onset of dialysis.