Hypertension Influences Recurrent Stone Formation in Nonobese Stone Formers

Previous studies have shown an association between obesity and recurrent stone formation, whereas recent epidemiologic studies have suggested an association between hypertension and stone formation. This study from Korea looked at the relationship between hypertension and recurrent stone formation. In this case control study, the authors used a database of 1200 calcium stone formers (SF) who had undergone stone evaluation at their institution. Of these, 228 patients were included in the study and divided into two groups: hypertensive SF (those who self-reported history of hypertension and treatment with antihypertensives) and normotensive SF. A metabolic evaluation including serum and urine chemistries was performed 4–6 weeks after stone management completion. Medications that may affect chemistries were discontinued 1 week before evaluation in both groups, except for antihypertensives in the hypertensive SF, which were continued. All SF were followed with abdominal radiograph and ultrasound examinations at 6- and 12-month intervals. Hypertensive SF were found to have lower levels of urinary pH, calcium, uric acid, and citrate than normotensive SF, whereas urinary oxalate was significantly higher in hypertensive SF. Of the 228 patients included in the study, 86 patients (37.7%) were included in the analysis of stone recurrence. Of these, 56 (65.1%) were hypertensive and 30 (34.9%) were normotensive. To exclude the effect of obesity, SF were divided into two more groups. In the non-obese group, hypertensive SF had a decreased time to stone recurrence. In the obese group, hypertensive SF and normotensive SF showed no significant difference in time to recurrence. The authors concluded that hypertension is associated with abnormal urine metabolism, as well as recurrent stone formation in the non-obese SF.