A LONGITUDINAL-STUDY OF TOTAL AND REGIONAL BONE-MINERAL CONTENT AND BIOCHEMICAL MARKERS OF BONE-RESORPTION IN PATIENTS WITH IDIOPATHIC HYPERCALCIURIA ON THIAZIDE TREATMENT

The effect of thiazides on total body bone mineral content and axial ( trunk) and peripheral (arms) bone mass was evaluated. First, dual-ener gy X-ray absorptiometry was used to study bone mass in 24 patients wit h idiopathic hypercalciuria and in 22 healthy subjects. Next, the pati ents were randomized into a group of 14 patients treated with chlortha lidone (50 mg/day) and a group of 10 untreated patients who served as controls; in these two groups biochemical and bone mass studies were r epeated 1 year later. Compared with healthy controls, patients with id iopathic hypercalciuria had less bone mass in total body(p < 0.02), ar ms (p < 0.001), and trunk (p < 0.05). After 1 year, the group of patie nts treated with thiazides manifested an increase of bone mass in tota l body (p < 0.0045), arms, and trunk (p < 0.0001) and a decrease in 24 -hour calciuria, urinary calcium/creatinine ratio, and serum tartrate resistant acid phosphatase concentration; the untreated group of patie nts lost bone mass in all three sites. Under baseline conditions, the groups of treated and untreated patients exhibited a negative linear r egression between total body bone mass and both urinary calcium/creati nine (r(2) = 0.234; p < 0.001) and serum tartrate resistant acid phosp hatase concentration (r(2) = 0.399; p < 0.0001). Our results confirm t he favorable effect of thiazides on bone mass and provide evidence of enhanced bone remodeling in idiopathic hypercalciuria.