referred affecting the compliance. Gastro intestinal intolerance was the most frequent side effects (84.21%). First visit before age 60 years ensures a better adherence during the FU (p=0.018). Co-morbidities reduce adherence (p=0.047). Weekly bisphosponates absuntion presents better compliance rates than daily (p=0.005). Patients with history of fractures have better adherence (p<0.001). Adherence results higher since the first year post-fracture (p=0.048) and remain higher during FU (p=0.004). Dividing population in adherent and non-adherent at the 85% MPR cut-off results that non-adherent have an RR=1.75 of fracture. Considering the 3 periods of FU, adherence seems to increase over time (84.53% – 87,64% – 91.19%; p=0.025) Major determinants of adherence already described in clinical trials and relationship between adherence and fracture risk are confirmed in this real life study. An adherence rate increase is also detected with fractures history (more motivation) and in patients in therapy from many years. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.387 P476 Relationship between baseline bone turnover marker levels and percent change in BMD at month 12 in postmenopausal women transitioned to denosumab or continuing on long-term alendronate therapy C. Roux a , M.A. Bolognese b , G. Bianchi c , J. Supronik d , I. Valter e , M.C. de Vernejoul f , D.L. Kendler g , H.G. Bone h , S. Ortolani i , S. Siddhanti j , H.S. Man j , J. San Martin j , M.L. Brandi k, * a Paris Descartes University Hôpital Cochin, Paris, France b Bethesda Health Research Center, Bethesda, MD, USA c Azienda Sanitaria Genovese, Genova, Italy d Niepubliczny Zaklad Opieki Zdrowotnej Centrum Medyczne, Bialystok, Poland e Center for Clinical and Basic Research, Tallinn, Estonia f Hôpital Lariboisiere, Paris, France g Clinical Research Centre, Vancouver, Canada h Michigan Bone and Mineral Clinic, Detroit, MI, USA i Istituto Auxologico Italiano, Milan, Italy j Amgen Inc., Thousand Oaks, CA, USA k Azienda Ospedaliera Careggi, Firenze, Italy Denosumab is an investigational fully human monoclonal anti- body that inhibits RANKL, a molecule that is essential for osteoclast formation, function, and survival. Through inhibition of RANKL, denosumab has been shown to decrease bone turnover, increase bone mineral density (BMD), and reduce the risk of fracture in post- menopausal women with osteoporosis. This randomized, double-blind, double-dummy study compared the effects of transitioning to denosumab (60 mg every 6 months subcutaneously) or continuing on branded alendronate therapy (70 mg weekly) on BMD in postmenopausal women (mean age, 68) with a lumbar spine (LS) or total hip (TH) BMD T-score </= -2.0 and >/=-4.0 who had received alendronate for at least the previous 6 months. The relationship between changes in BMD at the total hip or lumbar spine at month 12 and baseline bone turnover marker levels was evaluated. Subjects (253 denosumab, 251 alendronate) had a baseline mean LS BMD T-score of -2.63 and a median serum CTX-I level of 0.20 ng/ mL (range, 0.05–0.89 ng/mL). As previously reported, transition to denosumab produced greater increases in TH, LS, femoral neck, and 1/3 radius BMD than did continued alendronate (P </=0.012). BMD gains with alendronate were generally similar across quartiles of baseline bone turnover marker levels. With denosumab, BMD increases at month 12 at the total hip (Table 1) and lumbar spine were largest and differed most from the alendronate group, among subjects in the two highest quartiles of baseline CTX-I and PINP levels. In these postmenopausal women with low bone mass receiving long- term alendronate therapy, transitioning to denosumab from branded alendronate increased BMD, with the greatest incremental increase occurring among those women with the highest levels of bone turnover at baseline. Table 1 % Change in total hip BMD at Mo 12 by BL CTX-I. Baseline sCTX-I < 0.128 0.128–< 0.202 0.202–< 0.308 >= 0.308 DMAb N 62 62 63 54 BMD % ch. 1.58 1.38 2.16 ⁎ 2.65 ⁎⁎ 95% CI 1.03, 2.12 0.78, 1.97 1.57, 2.74 2.05, 3.24 ALN N 56 57 58 62 BMD % ch 1.24 1.24 1.15 0.68 95% CI 0.66, 1.82 0.61, 1.87 0.56, 1.74 0.12, 1.23 ⁎ P =0.015 vs alendronate. ⁎⁎ P < 0.0001 vs alendronate. Conflict of interest: C Roux, MA Bolognese, G Bianchi, I Valter, DL Kendler, HG Bone, S Ortolani, ML Brandi, Grant/Research Support, Amgen and/or Consultants, Speakers, or Advisory Boards, Amgen. doi:10.1016/j.bone.2009.03.388 P477 Serum calcium levels in postmenopausal women with osteoporosis after 1, 6 and 12 months of PTH(1–84) treatment — The latest results from the peak trial M. Díaz-Curiel a, *, D. Hosking b , M. Brandi c , L.H. Hyldstrup d , D. Felsenberg e a Servicio de Medicina Interna, Fundación Jiménez Díaz, Universidad Autonoma, Madrid, Spain b David Evans Medical Research Centre, Nottingham City Hospital, Nottingham, UK c Department of Internal Medicine, Metabolic Unit, University of Florence, Firenze, Italy d International Medical Scientific Strategy and Medical Marketing, Nycomed, Roskilde, Denmark e Centre of Muscle and Bone Research, Charité – Campus Benjamin Franklin, Free University and Humboldt-University, Berlin, Germany Background: Full-length PTH(1–84) is a potent anabolic agent currently used in the treatment of women with postmenopausal osteoporosis. The physiological role of PTH is to increase serum calcium. We report total serum calcium values after 12 months of treatment with PTH(1–84) in the PEAK (Preotact after a brEAK) trial. Methods: The PEAK study is an open-label, multicentre, Phase IIIb, randomised trial, investigating lumbar spine BMD changes in postmenopausal osteoporotic women. In the first year all patients are treated with PTH(1–84). Total serum calcium levels are measured at month 1, 6, and 12 at least 20 h after PTH(1–84) injection. 408 postmenopausal osteoporotic women aged >50 years with a lumbar spine T-score ≤-3.0 SD without abnormalities of calcium metabolism have been enrolled into the study. Women with serum calcium values >2.55 mmol/L (10.20 mg/dL) at baseline are excluded. Results: By October 2008 320 patients had been treated with PTH (1–84) for one month, 279 patients had received six months of treatment and 206 patients had received twelve months of treatment. At 1, 6 and 12 months the majority of patients (86, 78, and 94% respectively) had a serum calcium level below or equal to 2.55 mmol/ L or 10.20 mg/dL. Only 9,15 and 5% of patients respectively had mild elevations in serum calcium (>2.55–2.67 mmol/L or 10.20– Abstracts / Bone 44 (2009) S339–S450 S435