Renal emergencies in children represent a large and varied group of disease processes. This chapter will focus on common renal emergencies, including acute renal failure (ARF) in children, acute glomerulonephritis, and nephrotic syndrome. For discussion of other renal emergencies, see the following topics and chapters: end-stage renal disease (Chapter 52 “Emergencies in Renal Failure and Dialysis Patients”), urolithiasis (Chapter 56 “Urologic Stone Disease”), hypertension (Chapter 26 “Hypertension”), Henoch-Schönlein Purpura (Chapter 74 “Pediatric Abdominal Emergencies”), hemolytic uremic syndrome (Chapter 133 “Evaluation of Anemia and the Bleeding Patient”), and hematuria (Chapter 53 “Urinary Tract Infections and Hematuria”).
Acute renal failure (ARF) is the abrupt loss of renal function such that body fluid homeostasis can no longer be maintained. As a whole, ARF in children is relatively sporadic, with specific incidences related to individual causes. Some of the more common causes of ARF in children include severe dehydration, sepsis, pyelonephritis, hemolytic uremic syndrome, acute glomerulonephritis, postoperative complications, and posterior urethral valves in boys.
The clinical signs of ARF are varied and are determined by the underlying cause. Patients present with symptoms of the underlying cause (eg, bloody diarrhea and abdominal pain in hemolytic uremic syndrome; or fever, hypotension, and petechiae in sepsis). Ultimately, the patient will manifest stigmata of renal failure: nausea and anorexia due to uremia, headache from hypertension, edema (periorbital, scrotal or labial, dependent, or generalized), weight gain, and decreased urine output.
Diagnosis and Differential
ARF may be anatomically categorized as prerenal, renal, or postrenal in etiology. Table 86-1 lists common causes of renal failure in infants and children. Urinalysis helps distinguish among the three forms of ARF and should be obtained along with microscopic evaluation. Children who are not toilet-trained or those with significantly decreased urine output require catheterization to obtain urine. Prerenal causes of ARF are associated with little blood or protein on urinalysis, but typically manifest high urine specific gravity (> 1.025). Children with acute tubular necrosis typically have granular casts on urinalysis but usually have normal specific gravity. Glomerulonephritis and other glomerular diseases are characterized by hematuria and proteinuria. A positive urine dipstick test for blood without red blood cells on microscopy suggests hemoglobinuria or myoglobinuria. Basic blood tests such as serum electrolytes, BUN and creatinine, as well as a complete blood count (CBC) should be obtained in all cases of ARF to help identify the cause of the ARF and guide management. Additional blood tests may be indicated depending on the clinical scenario.
Table 86-1 Causes of Renal Failure in Infants and Children ||Download (.pdf)
Table 86-1 Causes of Renal Failure in Infants and Children
|Prerenal or Inadequate Renal Perfusion||Renal or Intrinsic Renal Injury or Disease||Postrenal or Obstruction|
|Dehydration from GI losses||Tubular diseases (tubular necrosis; effects of contrast agents, chemotherapy)||Solitary kidney|
|Blood loss ...|