Osteoporosis is a major cause of morbidity and fragility fractures in postmenopausal women. Bone mineral density (BMD) alone may not fully reflect fracture risk and skeletal fragility. Lumican, an extracellular matrix proteoglycan involved in collagen organization and musculoskeletal tissue homeostasis, has emerged as a potential biomarker for bone health. This prospective observational study aims to investigate the relationship between serum lumican levels, bone mineral density, muscle strength, and clinical fragility indicators in postmenopausal women. Approximately 100 participants will undergo routine osteoporosis assessment including DEXA, laboratory testing, FRAX evaluation, and handgrip strength measurement. The study will evaluate whether serum lumican levels can identify a hidden fragility phenotype beyond conventional bone mineral density measurements.

This is a prospective, observational, single-center clinical study designed to evaluate serum lumican levels in postmenopausal women undergoing routine osteoporosis assessment. The study will investigate the association of lumican with bone mineral density, handgrip strength, FRAX-based fracture risk, history of falls, and fragility fracture history. No treatment or interventional procedure will be applied. Serum lumican will be measured from venous blood samples, and all other clinical and laboratory data will be collected as part of standard osteoporosis evaluation. The study aims to explore whether lumican may contribute to the identification of fragility risk beyond conventional bone mineral density measurements.

Inclusion Criteria:

Inclusion Criteria:

• Female sex
• Age 45 years or older
• Postmenopausal status
• Attendance at the Physical Medicine and Rehabilitation outpatient clinic
• Undergoing routine bone mineral density (DEXA) assessment and osteoporosis laboratory evaluation
• Ability and willingness to provide written informed consent

Exclusion Criteria:

Exclusion Criteria:

• Premenopausal women
• Secondary causes of osteoporosis (e.g., malignancy, advanced renal failure, severe liver disease, significant endocrine disorders)
• Active infection or acute inflammatory disease
• Major surgery within the previous 6 months
• Neurological or muscular disorders that may significantly affect muscle function
• Inability to comply with study procedures and assessments
• Current treatment with medications that significantly affect bone metabolism, including bisphosphonates, denosumab, teriparatide, or other anti-osteoporotic agents
• Refusal or inability to provide written informed consent

Only postmenopausal women are eligible for participation because osteoporosis and fragility risk are being evaluated in a postmenopausal female population. Men and premenopausal women are excluded to ensure a homogeneous study population and to minimize the effects of sex- and hormone-related differences in bone metabolism.

The study population consists of postmenopausal women aged 45 years and older who attend the Physical Medicine and Rehabilitation outpatient clinic and undergo routine osteoporosis evaluation, including bone mineral density measurement by DEXA and standard osteoporosis laboratory testing. Participants will be recruited consecutively and enrolled after providing written informed consent.

Individual participant data will not be shared because no formal data-sharing plan has been established. Participant confidentiality and privacy will be protected in accordance with institutional and ethical requirements.