Metabolic Evaluation of Stone Disease

Urolithiasis is the third most common disease of the urinary tract after infections and diseases of the prostate. Furthermore, there has been an increasing prevalence of calcium stones in the industrialized countries and between 5% and 15% of the population will develop kidney stones during their lifetime. Calcium stones (calcium oxalate or phosphate) compose the most common stone type. Other stone compositions include uric acid, struvite (magnesium ammonium phosphate), and other miscellaneous components such as cystine. Advances in minimally invasive techniques have dramatically changed surgical management of stone disease in the last 2 decades. However, medical management of stone disease along with prevention of recurrent stones represents a less invasive and more cost-effective approach. In this concept, an understanding of the pathophysiology of stone formation is the prerequisite for a cost-effective medical evaluation and management as well as the prevention of recurrences. Although significant knowledge has been gained regarding pathophysiology of stone disease, this has not translated in a similar dramatic change in the medical management and prevention. One reason for this discrepancy may be the fact that the etiology of recurrent calcium stones in many patients remains unclear and/ or is multifactorial. Dietary and environmental factors certainly play an important role and long-term control of recurrences can be achieved in many patients with general measures for stone prevention. In this article, the pathophysiology of stone formation is reviewed, followed by a detailed discussion of the current recommendations for metabolic evaluation. Also, the medical management based on the results of metabolic evaluation is presented at the end.