[Renal lithiasis. Biochemical changes in the follow-up].

With the aim of assessing if biochemical changes occur in the follow up of patients with renal lithiasis, 237 patients were studied (115 women and 122 men, mean age 39 +/- 8 and 42 +/- 7 years, respectively) and controlled during 27.3 +/- 19.3 months. All of them had previously undergone metabolic evaluations at baseline and one or more than one control studies afterwards. Patients with a diagnosis of sponge kidney, renal tubular acidosis, primary hyperparathyroidism, anatomical malformations of the urinary tract, or urinary infections were not included. Two populations were identified: those who presented changes in the baseline diagnosis (139 patients, Group I) and those who presented no changes (98 patients, Group II). In these groups, no differences were observed in baseline metabolic diagnoses or in the follow-up period. Hypocitraturia was the additional diagnosis most frequently observed (43.1%), followed by Idiopatic hypercalciuria (20.8%) and abnormalities of uric acid (16.5%). In the group of 110 patients followed up for more than 3 years, 37 patients recurred (33%). Among the latter, 25 (23%) changed the baseline metabolic diagnosis vs. 12 (11%) that maintained the same diagnosis (p < 0.002). Changes in metabolic disorders were frequently observed in the follow up of patients with nephrolithiasis. These changes are not necessarily associated with the diet indicated or drug treatment. Hypocitraturia was the additional metabolic disorder most frequently found. In general, there is a higher recurrence rate in those patients who present changes in their biochemical parameters and undergo no treatment.