Calcitonin has been used for many years for treating osteoporosis in postmenopausal women. Recent data from the 2 years placebo-controlled QUEST study have shown a preservation of microarchitecture as measured by high resolution MRI in postmenopausal women with prevalent vertebral fractures at baseline.This pilot study should provide additional new insights in the mode of action of nasal calcitonin, on structural changes as measured by high resolution peripheral CT, and on the comparison between weight bearing and non weight bearing bones in postmenopausal women.

Inclusion Criteria:

• Women between age 45-70
• Natural or surgical menopause ≥ 1 year
• T-Score between 0.0 and -2.49 (spine or proximal femur - total or femoral neck measured by DXA)

Exclusion Criteria:

• Osteoporosis (T-score ≤ -2.5 in spine or proximal femur - total or femoral neck, measured by DXA)
• Severe vertebral fracture, as identified by screening DXA assessment
• Any history of metabolic disease, which could affect bone metabolism: hyperparathyroidism, osteogenesis imperfecta, Paget's disease, osteomalacia
• Thyroid disease (if receiving thyroid hormone replacement, the patients must be euthyroid, and on a stable dose of thyroid hormone)
• Impaired renal function (estimated GFR<30 ml/min)
• History of previous or active malignancy of any organ system, treated or not treated within the past 5 years.
• History of corticosteroids treatments during 6 months or more, daily dosage >5 mg .
• BMI < 18 or >30.
• Treatments with estrogens, SERMs, tibolone, calcitonin, strontium ranelate, teriparatide or PTH, oral or iv bisphosphonates in the previous year.