Estudio de la variabilidad de los parámetros de riesgo de cristalización en orina de 12 horas diurna y nocturna

Resumo

The analysis of the urinary composition is essential to the evaluation of renal lithiasis and depends on an adequate sample collection and processing. The aim of this study is to examine circadian variations of stone-promoting and stone-inhibiting factors in urine using split 24-h samples from healthy and stone-forming children and adults. This study indicates that urine composition changes throughout the day, with daily variability in most of the parameters related to kidney stone formation. Thus, the overnight urine samples in all groups had higher levels of phosphorous and magnesium, lower volume, lower pH, and less citrate and uric acid. Furthermore, this circadian pattern in solutes excretion seems to be fulfilled in healthy and stone-forming subjects. Urine collected during the night period presents a greater risk of urinary crystallization. In order to evaluate a simplified metabolic urinary stone study, we compared the metabolic alterations detected in the 12-h overnight urine and 24-h urine. Despite the limitations of our study, the 12- hour night-time urine sample seems to be useful in the metabolic evaluation of kidney stone disease and it would be of great interest to provide of adapted reference values.