The Effects of Estrogen Replacement Therapy in Postmenopausal Women With Hypercalciuria and Low Bone Mass

Inclusion Criteria: * Postmenopausal women * Diagnosis of hypercalciuria * Diagnosis of low bone mass * Vitamin D replete (serum 25-hydroxyvitamin D level \>35 ng/mL) Exclusion Criteria: * Secondary causes of hypercalciuria (primary hyperparathyroidism, sarcoidosis, vitamin D excess, malignant neoplasm, and renal tubular acidosis) * Other metabolic bone disease (primary hyperparathyroidism, hyperthyroidism, hypercortisolemia, severe gastrointestinal disorders, liver cirrhosis, renal failure (Cr \>1.5), active malignancy including multiple myeloma, rheumatological diseases, and Paget's disease of bone) * Use of medications affecting bone and calcium metabolism (corticosteroids in the previous 3 months, suppressive dose of thyroid hormone, calcium channel blockers, anti-convulsants, aromatase inhibitors, thiazolidinediones, and cyclosporine A) * History of coronary artery disease * Breast cancer or suspected estrogen-dependent neoplasia * Previous venous thromboembolic event * Stroke * Active liver disease * Tobacco use within the past 6 months * Negative colonoscopy within the previous 10 years or sigmoidoscopy within the previous 5 years * Negative mammogram within the previous 2 years * Negative Pap smear within the previous 3 years in women \< or = 65 years old with an intact cervix * No vaginal bleeding within the prior 5 months. * Age \> or = 70 * \> or = 20 years since last menstrual period or use of hormone replacement therapy