FAMILY HISTORY AND RISK OF KIDNEY-STONES

Kidney stones develop more frequently in individuals with a family his tory of kidney stones than in those without a family history; however, little information is available regarding whether the increased risk is attributable to genetic factors, environmental exposures, or some c ombination. In this report, the relation between family history and ri sk of kidney stone formation was studied in a cohort of 37,999 male pa rticipants in the Health Professionals Follow-up Study. Information on family history, kidney stone formation, and other exposures of intere st, including dietary intake, was obtained by mailed questionnaires. A family history of-kidney stones was much more common in men with a pe rsonal history of stones at baseline in 1986 than in those without a h istory of stones (age-adjusted prevalence odds ratio, 3.16; 95% confid ence interval [CI], 2.90 to 3.45). During 8 yr of follow-up, 795 incid ent cases of stones were documented. After adjusting for a variety of risk factors, the relative risk of incident stone formation in men wit h a positive family history, compared with those without, was 2.57 (95 % CI, 2.19 to 3.02). Family history did not modify the inverse associa tion between dietary calcium intake and the risk of stone formation. T hese results suggest that a family history of kidney stones substantia lly increases the risk of stone formation. In addition, these data sug gest that dietary calcium restriction may increase the risk of stone f ormation, even among individuals with a family history of kidney stone s.