To investigate the use of fish oil in the dietary management of hypercalciuric stone formers. Prostaglandins have been linked to urinary calcium excretion, suggesting a role for omega-3 fatty acids in the treatment of hypercalciuric urolithiasis.

We retrospectively studied a cohort of patients treated at our stone clinics from July 2007 to February 2009. Patients' urinary risk factors for stone disease were evaluated with pre- and post-intervention 24-hour urine collections. All patients received empiric dietary recommendations for intake of fluids, sodium, protein, and citric juices. All subjects with hypercalciuria (urinary calcium >250 mg/d for males or >200 mg/d for females) on at least two 24-hour urine collections were counseled to supplement their diet with fish oil (1200 mg/d).

Twenty-nine patients were followed for 9.86 ± 8.96 months. The mean age was 43.38 ± 13.78 years. Urinary calcium levels decreased in 52% of patients, with 24% converting to normocalciuria. The average urinary calcium (mg/d) decreased significantly from baseline (329.27 ± 96.23 to 247.47 ± 84.53, P <.0001). Urinary oxalate excretion decreased in 34% of patients. The average urinary oxalate (mg/d) decreased significantly from baseline (45.40 ± 9.90 to 32.9 ± 8.21, P = .0004). Urinary citrate (mg/d) increased in 62% of subjects from baseline (731.67 ± 279.09 to 940.22 ± 437.54, P = .0005). Calcium oxalate supersaturation decreased in 38% of the subjects significantly from baseline (9.73 ± 4.48 to 3.68 ± 1.76, P = .001).

Omega-3 fatty acids combined with empiric dietary counseling results in a measurable decrease in urinary calcium and oxalate excretion and an increase in urinary citrate in hypercalciuric stone formers.