ABSTRACT
Acute renal failure (ARF) is defined as a sudden decrease of normal kidney function that compromises the normal renal regulation of fluid, electrolyte, and acid-base homeostasis.1 In practical terms ARF is characterized by a reduction in the glomerular filtration rate (GFR), which results in an abrupt increase in the concentrations of serum creatinine and blood urea nitrogen (BUN). The effect on urine volume in ARF is variable: patients may be anuric, oliguric, and, in some cases, polyuric. ARF develops over a period of hours to days, whereas chronic renal failure (CRF) progresses over months to years. In many circumstances there is little difficulty in discerning between ARF and CRF. Short stature, renal osteodystrophy, delayed puberty, normocytic anemia, and hyperparathyroidism all suggest CRF. However, it may be difficult to differentiate ARF from CRF without imaging studies and a kidney biopsy. Furthermore, at the time of presentation, a patient with CRF may have a superimposed ARF – this is referred to as acute on chronic renal failure. ARF is usually encountered in pediatric urologic patients as a complication of underlying chronic renal disease. The three most important contexts in pediatric urologic practice are acute pyelonephritis, aminoglycoside toxicity, and acute obstructive uropathy. Urologists must be alert to the possibility of ARF in any patient referred with macroscopic hematuria. The three most important contexts are urinary tract infection, glomerulonephritis, and myoglobinuria. Extracorporeal shock wave lithotripsy (ESWL) is the urologic treatment of choice for the majority of patients with renal or proximal ureteral stones.2 Very rarely, bilateral or unilateral ESWL has been associated with ARF even in the absence of obstruction.3 In order to diagnose the underlying cause of ARF and treat the metabolic complications, all patients should undergo a full evaluation by a pediatric nephrologist at the time of presentation.
