Teriparatide (Forsteo) Treatment in Postmenopausal Women: Mechanism of Action

Inclusion Criteria Subjects must: * Have a bone mineral density T-score (at the lumbar spine or total hip) of less than or equal to -2.5 * Be female * Be at least 5 years post menopausal (more than 5 years since their last menstrual period) but \<85 years old. * Be ambulatory * Be able and willing to participate in the study and provide written informed consent * Have a serum 25(OH)2 vitamin D3 \>50 nmol/L (after vitamin D3 loading) Exclusion Criteria Patients will not be admitted to the study if they exhibit any of the following: * Evidence of a clinically significant organic disease which could prevent the patient from completing the study * A body mass index less than 18 or greater than 35 * Abuse of alcohol or use illicit drugs (information obtained from medical history) or who consumed more than 4 servings of any alcoholic beverage one day prior to the visit (i.e., subjects who might be binge drinkers) * Any history of cancer within the past 5 years excluding skin cancer non melanomas * Any history of ongoing conditions or diseases known to cause abnormalities of calcium metabolism or skeletal health including Paget's disease of bone * Chronic renal disease (as defined by an estimated glomerular filtration rate of ≤ 30mL/min) * Acute or chronic hepatic disease * Malabsorption syndromes * Hyperthyroidism as manifested by TSH outside the lower limit of the normal range * Hyperparathyroidism * Hypocalcemia or hypercalcemia * Osteomalacia * Cushing's syndrome * Current …