[Metabolic diagnosis.].

Kidney stones is a prevalent condition with a rising incidence in the last few decades. Diseasere lapse is an especially important issue, that requires further investigations in order to prevent new episodes. Adequate work up must be suited to patients´ characteristics such as age and the presence of risk factors forrecurrence. An initial approach should focus on a thorough clinical history, with special attention to dietary habits, analysis of the stone composition when available, and basic blood and urine exams to guide further investigations. In this article, we aim to explain proper metabolic evaluation in kidney stone formers, explaining its indications, how to perform it and how to interpret it, in order to stablish an adequate treatment. Special attention will be given to: hypercalciuria, yperoxaluria, hyperuricosuria, hypocitraturia, hypomagnesuria, hyperparathyroidism and the most frequent disturbances in urine analysis.