[Urinary lithiasis: epidemiology and physiopathology].

Urolithiasis has an incidence of about 12% in men and about 5% in women before the age of 70 years. Several epidemiological factors are involved in the predisposition to the urinary stone disease, notably: age, sex, race, climate, geography, profession, social class, nutritional factors and inherent genetic particularities. A number of physicochemical mechanisms govern lithogenesis, passing from saturation and supersaturation of urine to nucleation, crystallization and crystal growth to clinically significant sizes when the inhibition mechanisms are overwhelmed or absent. Generally urinary stone are of diverse aetiologies, that can essentially be grouped in calcium, uric acid, cystine and magnesium ammonium phosphate stones with subgroups in relation to the varied pathophysiological mechanisms involved in each case.