Hypercalciuria and postglomerular hematuria in children. The effects of thiazide on calcium excretion, urine saturation with respect to calcium-hydrogenphosphate and hematuria.

Calcium-hydrogenphosphate was considered as one of the main factors governing renal calculus formation. The degree of saturation (expressed as activity product = AP) with respect to this phase was therefore calculated in urines of 36 hypercalciuric children (20 absorptive, 16 renal subtype) with isolated hematuria and 30 healthy controls. The effect of thiazide treatment on the urine saturation and on the evolution of hematuria was also investigated. The results were compared to the urinary calcium excretion (expressed as Ca/cr ratio). Urines of both hypercalciuric groups were saturated on basal conditions (AP above 3.5 x 10-6 mol2/l2; -lgAP below 6.4), the values differed significantly from those of the controls (-lgAP = 6.78 +/- 0.4 in the control-; 6.1 +/- 0.25 in absorptive-, 6.03 +/- 0.34 in renal hypercalciuria; p less than 0.001). Thiazide normalized the activity product in all groups. During thiazide therapy significant decrease in the occurrence of hematuria was noted (p less than 0.001 in both hypercalciuric groups). These data furnish further evidence on the relation of hypercalciuria and postglomerular hematuria. Simultaneous determinations of the state of saturation may provide further information on the "stone forming potential" of the urines investigated.