According to researchers, kidney stone history may be a risk factor that impacts clinical management.
For the meta-analysis, investigators led by Wisit Cheungpasitporn, MD, of Mayo Clinic in Rochester, Minn., calculated CHD risk based on 52,791 patients with kidney stones. Data was pooled from observational cohort studies and a cross-sectional study, each with control groups. The researchers also conducted a separate sensitivity analysis.
Compared with individuals without kidney stones, stone formers had a 24% greater risk of CHD, according to results published in the North American Journal of Medical Sciences. For female stone formers, the risk was 43%. The association was not statistically significant in males.
The investigators suggested plausible explanations for the findings. First, kidney stones may be associated with CHD risk factors. Studies have found an association between stone formation and features of the metabolic syndrome, including obesity, hypertension, and dyslipidemia. Stone formers, particularly those with uric acid stones, have a higher prevalence of diabetes and glucose intolerance. In a study, researchers found an association between after-meal insulinemia and increased urinary calcium and phosphorus excretion in patients with kidney stones.
Second, a history of kidney stones has been independently associated with CHD, raising the hypothesis that kidney stone formation has a vascular pathogenesis. The process leading to calcium buildup in the coronary arteries may be the same mechanism contributing to calcium buildup in renal tubules. A recent study found that the composition of vascular plaques is identical to Randall’s plaque, the nidus of stone formation. In addition, a deficiency of pyrophosphates, which are inhibitors of calcification, in both blood and urine could explain the link between CHD and kidney stone formation.
It is surprising that females with kidney stones were more likely to develop CHD, the investigators highlighted, because both CHD and kidney stones are more common in males. The reasons for the findings are still unclear. Female stone formers may be exposed to unknown factors that increase their CHD risk. Future studies might examine factors such as diet, estrogen and progesterone, pregnancy, muscle-to-fat composition, and genetic factors, they suggested.