When and how to evaluate a patient with nephrolithiasis.

Nephrolithiasis is a common disorder that afflicts up to 12% of the population and continues to be a significant cause of patient injury. Evaluation of these patients should include the assessment of their comorbidities and underlying medical conditions. Patients who form stones can undergo a streamlined evaluation. A cause can be found in more than 90% of these patients. With medical treatment, stone-recurrence rates can be decreased by 85% for calcium oxalate stone formation, which affects a large proportion of patients. Introduction of nonspecific medical therapy in uncomplicated calcium stone disease may improve the quality of life for these patients and allow utilization a simple diagnostic protocol. This is in contrast to the previous recommendations of disease-specific therapy. Because patients without complications represent the majority of those who form stones, a simplified approach greatly reduces the cost of evaluation and treatment. Underlying medical conditions, however, require disease-specific therapy. The protocol represented here should aid physicians and patients in the approach to management of stone disease. The fasting calcium-load test is not required, and the entire evaluation can be performed in an ambulatory setting in two visits. Two 24-hour urine samples should be obtained on a random and restricted diet. Patients who form calcium stones can be subdivided into those who form hypercalciuric and normocalciuric stones. Patients who form normocalciuric stones are treated with conservative measures (increased fluid intake) and potassium and magnesium citrate. Patients who form hypercalciuric stones are treated with a combination of thiazides and potassium and magnesium citrate.