URINARY-EXCRETION SUBSTANCES IN PATIENTS WITH CYSTIC-FIBROSIS - RISK OF UROLITHIASIS

Patients with cystic fibrosis (CF) have an increased risk of urolithia sis/nephrocalcinosis. To determine potential mechanisms responsible, w e studied the urinary excretion of lithogenic and stone-inhibitory sub stances and calculated the urinary saturation for calcium-oxalate (CaO x), brushite (CaHPO4), and uric acid (UA), We examined 24-h urines in 63 patients with CF (34 female, 29 male) aged 5 months to 36 years. Re nal ultrasonography was performed at the time of urine collection. Hyp eroxaluria was found in 25 patients (range 0.51-1.71 mmol/1.73 m(2) pe r 24 h). Urinary Ca was increased in 13 patients (4.1-8.22 mg/kg per 2 4 h). Hyperuricosuria was found in 16 patients (5.2-18.0 mmol/1.73 mt per 24 h) and hypocitraturia in 14 patients (0.07-1.14 mmol/1.73 m(2) per 24 h). CaOx saturation was elevated in 26 patients, related to hyp eroxaluria in 19 patients. CaHPO4 saturation was increased in 19 patie nts and UA saturation in 11 patients. Urolithiasis in situ was diagnos ed in 1 patient; 3 patients previously had renal stones; 4 patients ha d present nephrocalcinosis, Elevated excretion of lithogenic substance s and urinary supersaturation might lead to the higher risk of urolith iasis/nephrocalcinosis in patients with CF.