Correspondence between Ca²âº and calciuria, citrate level and pH of urine in pediatric urolithiasis.

BACKGROUND: Hypercalciuria and hypocitraturia are considered the most important risk factors for urolithiasis. Citrate binds to urinary calcium to form a soluble complex which decreases the availability of ionized calcium (Ca(2+)) necessary for calcium oxalate formation and phosphate crystallization. The aims of this study were to assess the Ca(2+) fraction in relation to total calciuria, citraturia and urinary pH and to determine whether urinary Ca(2+) concentration is a helpful biomarker in metabolic evaluation of children with urolithiasis. METHODS: We collected 24-h urine samples from 123 stone-forming children and adolescents with hypocitraturia and from 424 healthy controls. Total calciuria (total calcium, Catotal), Ca(2+), pH, citrate, oxalate and Bonn Risk Index (BRI) were assessed and compared between the two groups. RESULTS: Total calciuria and Ca(2+) content were higher in stone-formers than in the healthy children. In both stone-formers and controls, Ca(2+) content was inversely related to citraturia and urinary pH, whereas the Ca(2+)/Catotal ratio differed slightly between the groups. A large variability in Ca(2+) level was found across individuals in both groups. The BRI increased with increasing calciuria and urine acidity. CONCLUSIONS: Compared to controls, stone-formers with hypocitraturia demonstrated a higher urinary Ca(2+) concentration, but this was proportional to calciuria. The large individual variability in urinary Ca(2+) content limits its practical use in metabolic evaluation of children with urolithiasis. However, the Ca/Citrate ratio may be a useful clinical tool in evaluating children with urolithiasis.

Urinary nerve growth factor level in children with neurogenic bladder due to myelomeningocele.

OBJECTIVE: Myelomeningocele is the most common physically disabling birth defect in humans. It is caused by the failure of the neural tube to close and is most common in the lumbosacral area. Because of associated neurogenic bladder dysfunction, children with myelomeningocele have an increased risk of urinary tract infections and, ultimately, of kidney damage. Nerve growth factor (NGF) is an important mediator inducing bladder overactivity in many pathological conditions. The aim of this study was to evaluate urinary NGF excretion in children with neurogenic bladder caused by myelomeningocele. MATERIAL AND METHODS: The investigation was conducted into two groups. Group 1 comprised 28 children with neurogenic bladder, and group 2 comprised 20 healthy children with no abnormalities in the urinary and nervous systems. Urinary NGF levels were measured by enzyme-linked immunosorbent assay. RESULTS: Median urinary NGF concentration in group 1 was higher when compared with healthy controls. Positive correlations between urinary NGF level and detrusor pressure at maximum bladder capacity, and negative correlations between NGF and bladder wall compliance were found. CONCLUSIONS: Urinary NGF levels were significantly elevated in patients with myelomeningocele. Future studies are needed to examine further the significance of urinary NGF levels in the pathogenesis of neurogenic bladder in this clinical condition.