Focusing on postmenopausal women with reduced bone density, the present study aimed: (1) to describe the different phenotypes associated with hypercalciuria in patients with osteopenia/osteoporosis, pointing on kidney, bone, and biochemical features; and (2) to analyze the efficacy of TZD treatment on reduction of renal calcium excretion, normalization of circulating PTH levels, hypercalcemia development, and on bone mineral density. This evidence concerns the gene PTH and Hypercalcemia.