The main purpose of this study is to determine the safety and effectiveness of three week daily subcutaneous injections of Parathyroid Hormone-related Protein (1-36). Previous studies indicated that PTHrP has a skeletal 'anabolic' or bone-building effect, and has shown to increase bone mineral density in postmenopausal women with osteoporosis. Safety of PTHrP will be determined by measurements of blood pressure and pulse, serum blood calcium levels and subjective symptoms. Effectiveness will be measured by changes in measurements of blood and urine markers of bone turnover.