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OneLiner

Microscopic evaluation of the stone is an important key to identifying the cause. A hexagonal shaped microscopic crystal is characteristic of cystinuria. Patients with cystinuria typically have increased levels of lysine and arginine in their urine due to a defect in amino acid reabsorption in the proximal tubule which leads to wasting of lysine, arginine, cystine, and ornithine. The elevated cystine level in the urine leads to recurrent stone formation. Treatment involves hydration and alkalization of the urine with acetazolamide.