Estrogen deficiency accelerates bone turnover and underlies postmenopausal osteoporosis.The ovariectomized rabbit is a model of this condition, but the point at which bone loss becomes established and its temporal biochemical profile remain poorly characterized. This descriptive study assessed whether the serum pattern of estrogen-deficiency bone loss develops and becomes established by week 12 in this model, quantifying four markers of estrogenic status and bone turnover at baseline and at 12 and 20 weeks after ovariectomy. Ten adult female New Zealand White rabbits (Oryctolagus cuniculus) underwent bilateral ovariectomy; three additional animals provided baseline reference values. Estradiol, parathyroid hormone, the beta-isomerized C-terminal telopeptide of type I collagen (β-CTx, resorption), and osteocalcin (formation) were measured by chemiluminescence immunoassay. Changes over time were assessed with the Friedman test and Wilcoxon pairwise comparisons with Holm correction. All markers changed significantly. Relative to baseline, by week 12 estradiol had already decreased and β-CTx and osteocalcin had already increased significantly, becoming more pronounced by week 20: estradiol fell by 91 %, β-CTx rose by 145 %, and osteocalcin by 68 %, whereas parathyroid hormone fell by 39 %. The resorption/formation ratio increased steadily, indicating a progressive predominance of resorption. Baseline values in ovariectomized animals did not differ from reference values. These findings describe the establishment, from week 12, of a high-turnover state consistent with osteopenia and its progression to osteoporosis in the ovariectomized rabbit and identify β-CTx as the most sensitive marker of the panel.

KEY WORDS: Osteoporosis; Ovariectomy; Bone remodeling; Estradiol.