At least 350 healthy controls, 100 hypertensive non stone formers without treatment, 150 normotensive stone formers and 100 hypertensive stone formers without treatment will be enrolled in the study. Both the controls and the stone formers will be subdivided according to a 4-class BMI scale. The classes will have the following characteristics: Class 1 BMI £ 18.9 (underweight condition); Class 2 BMI between 19 and 24.9 (normal weight condition); Class 3 BMI between 25 and 29.9 (excess weight condition); Class 4 BMI > 30 (obesity). The patients enrolled will have their medical history recorded after which they will be subjected to the measurement of anthropometric parameters and arterial blood pressure, and a stone risk mini-profile will be drawn up including volume, creatinine, sodium, potassium and calcium measured according to the methods published. As is well-known, 24-h urinary sodium is considered the "gold standard" for the assessment of food-related salt intake, creatinine is a sensitive marker of lean mass, potassium is an index of the body's alkaline potential and calcium has the important pathophysiological role described above.