Chapter 33: Alterations of Renal and Urinary Tract Function in Children

Structural abnormalities represent a significant cause of renal compromise in children, including hypoplastic and dysplastic kidneys that fail to develop normally, polycystic kidney disease characterized by multiple fluid-filled cysts, and renal agenesis in which one or both kidneys fail to form, with bilateral agenesis resulting in Potter syndrome and fetal incompatibility with life. Ureteropelvic junction obstruction creates hydronephrosis through impaired urine drainage and may necessitate surgical intervention, while congenital malformations of the external genitalia such as hypospadias and bladder exstrophy require reconstructive procedures. Acquired glomerular disorders include acute poststreptococcal glomerulonephritis, an immune complex-mediated disease presenting with hematuria and proteinuria following streptococcal infection; immunoglobulin A nephropathy, the most prevalent glomerulonephritis globally in children, manifesting with recurrent hematuria; and nephrotic syndrome, typically from minimal change disease, characterized by massive proteinuria, hypoalbuminemia, and lipidemia with increased susceptibility to secondary infections. Hemolytic uremic syndrome, predominantly triggered by Shiga toxin from pathogenic E. coli, causes a microangiopathic hemolytic anemia with thrombocytopenia and acute kidney injury. Nephroblastoma or Wilms tumor represents the most common renal malignancy in young children, associated with genetic mutations and responsive to multimodal therapy. Urinary tract infections, frequently caused by uropathogenic E. coli, range from lower tract cystitis to upper tract pyelonephritis, with vesicoureteral reflux permitting retrograde urine flow and increasing infection and scarring risk. Urinary incontinence beyond expected developmental age may result from organic causes including neurogenic bladder, anatomic anomalies, and metabolic disorders, or from psychological factors, with intervention strategies spanning behavioral modification, pharmacotherapy, and management of underlying conditions.