STUDY OF ETIOLOGIC FACTORS IN NEPHROLITHI ASIS - THE ROLE OF CRYSTALLIZATION INHIBITORS

Background: five percent of consultations at the Emergency Room of Cat holic University Hospital are due to nephrolithiasis. The causes of th is high frequency remain unknown. Aim: to know the main metabolic and anatomic factors involved in the genesis of neprholithiasis. Patients and methods: forty one patients (31 male) were studied presenting with a renal colic were studied as soon as the acute episode subsided and without diet modifications. Fasting blood calcium and creatinine and 2 4 h urine calcium, uric acid, citrate, magnesium and pH were measured and an intravenous pyelogram was performed. Twenty one subjects withou t a history of nephrolithiasis were used as controls. Results: Patient s with nephrolithiasis did not differ from controls in urinary calcium (159 +/- 67 and 172 +/- 67 mg/24 h respectively), uricosuria (417 +/- 171 and 431 +/- 121 mg/24 h respectively) or urinary magnesium (55 +/ - 19 and 62 +/- 21 mg/24 h respectively, whereas urinary citrate was l ower (219 +/- 172 vs 319 +/- 179 mg/24 h in controls p < 0.05). All pa tients had normal renal functions, urinary acidification and intraveno us pyelogram. Seven percent of patients with nephrolithiasis had hyper calciuria, 2.4% had hyperuncosuria, 68.3% had a low urinary citrate an d 44.4% had low urinary magnesium. Conclusions: in this sample, there is a strong association of nephrolithiasis with low levels of crystall ization inhibitors in special with urinary citrate, a crystallization inhibitor.