Urinary stone disease: a practical guide to metabolic evaluation.

Urolithiasis is the third most common affliction of the urinary tract, after infections and diseases of the prostate. Approximately 10% of the North American population will have at least one urinary calculus by age 70. A thorough history and physical examination will usually confirm the diagnosis of urinary stone disease. A simplified laboratory evaluation may be performed for patients with a single stone episode. A more extensive evaluation is required for patients with recurrent, metabolically active stones and patients at high risk (ie, cystine stone formers and those who develop bladder dysfunction or nephrosclerosis). Intravenous pyelography with tomography remains the gold standard for imaging of the urinary tract to confirm the diagnosis and formulate a treatment plan.