Do you recommend any specific testing for patients with recurrent nephrolithiasis and suspected absorptive hypercalciuria?

I would consider genetic testing in this situation, although it would not alter my recommendations for diet and thiazide diuretic treatment. I would also look for primary hyperparathyroidism. Counterintuitively, parathyroid hormone increases absorption of urinary calcium; that’s why HPT patients are often hypercalcemic.

Stephen B. Erickson, MD.

I agree with the comments by Drs. @Dr. First Last and @Dr. First Last, but I would also add that the treatment trial demonstrating the benefit of adequate dietary calcium (at least 1,000 mg daily with meals) in preventing calcium oxalate stone recurrence in hypercalciurics did not distinguish between hyperabsorbers and hypersecretors (Borghi et al., PMID 11784873). The University of Texas Southwestern group data from the 1990's suggested that most hypercalciuric patients are hyperabsorbers (2:1), so this condition should not alter stone prevention treatments.