Pseudoephedrine and guaifenesin urolithiasis: widening the differential diagnosis of radiolucent calculi on abdominal radiograph

Unenhanced helical computed tomography has played an increasingly important role in the management of urinary tract stones, guiding diagnosis and control of calculus disease. We report computed tomographic and radiographic appearances of a renal calculus composed of pseudoephedrine and guaifenesin in a patient who abused over-the-counter allergy medication.