ANALYSIS OF CHILDREN WITH POSTRENAL ACUTE RENAL FAILURE

Abstract

Acute renal failure (ARF) is defined as rapid deterioration of renal function associated with accumulation of nitrogenous wastes and electrolyte imbalance in the body. Postrenal ARF results from mechanical or functional obstruction of the urinary tract, and is a relatively rare condition in children. We analysed causative disorders and clinical courses of 18 children with postrenal ARF who had been treated in our clinic from July, 1973 to December, 1987.
1) Conditions causing postrenal ARF.
Congenital urinary tract obstruction accounted for 90% of the patients, and posterior urethral valve was the most common lesion (8 children). Among other congenital conditions were pelvi-ureteric junction stenosis (hydronephrosis), bladder diverticulum, ectopic ureterocele, and hydrometrocolpos. Acquired obstructive lesions caused the condition in 2 patients; a 2-year-old girl with bilateral ureteral stone and a 1-year-old boy with false anuria from extended prostatic rhabdomyosarcoma.
2) Clinical presentations and their onset
Abdominal swelling due to distendd bladder or enlarged kidney was seen in 11 patients (61%). High fever from acute pyelonephritis or sepsis was the clue in 6 patients to the underlying urological disorders. In 5 patients, symptoms of gastrointestinal tract, such as diarrhea or vomiting, led to urological check-up. Decreased amniotic fluid and severe urinary tract dilatation was detected in a boy with posterior urethral valve through prenatal ultrasonography.
In about two thirds of the patients, clinical presentations became apparent within one month after birth. Two patients with acquired lesions presented their symptoms after they reached 6 months old.
3) Management
The emergent management of postrenal ARF consists of three principles; infusion therapy and/or dialysis to correct metabolic and electrolyte imbalance, antibacterial therapy to cope with pyelonephritis and sepsis, and immediate urinary drainage. Urethral catheter drainage was made in 11 patients, nephrostomy in 4 and cystostomy in one.
4) Prognosis
Adequate medical treatment and urinary drainage permitted prompt normalization of serum electrolytes. Improvement of renal function determined by serum creatining or BUN was observed during the first 2 or 3 weeks after the relief of obstruction. Follow-up studies for more than 3 years revealed impaired renal function in 10 children (55%). To predict the recovery of renal function, fractional excretion of sodium (FE_Na) and renal failure index (RFI) 2 or 3 weeks after urinary drainage were found useful.