A previously well woman, 44 years of age, presented with 3 years of recurrent bilateral renal colic. Despite an increase in fluid intake and a low calcium diet, the intermittent episodes of renal colic continued and had become more frequent in the last year. An abdominal X-ray was performed, which showed some radio-opaque areas on both renal silhouettes (see Figure 1). Two stones in the right pelvic ureter were also seen following administration of contrast. No obstruction of the urinary tract was evident. Urinalysis revealed leukocyturia, a pH of 6.5 and specific gravity of 1.015. Blood testing showed hypercalcaemia of 2.96 mmol/L and hypophosphataemia of 0.71 mmol/L.