Fracture Risk Assessment in People with Osteoporosis/Osteopenia with Urine NTx (Urinary N-Terminal Telopeptides): An Exploratory Retrospective Study

Background and Aims: The “quantity” of bone can be evaluated by dual-energy X-ray absorptiometry (DXA) scans, but not its “quality. We aim to study the clinical relevance of urinary-N-terminal telopeptide (NTx) in a retrospective exploratory study. Patients and Methods: The medical records of patients with osteoporosis, osteopenia with or without fractures, and with available urinary NTx were retrospectively reviewed; those on anti-osteoporotic medication before the start of the study were excluded. In all NTx levels, bone-specific alkaline phosphatase (BSAP), parathormone, serum calcium, and vitamin D were measured. In all cases, a recent DXA scan and fracture risk assessment (FRAX) had been performed. Appropriate statistics were applied using SPSS. 15. Results: Included were 93 patients (17.2% males); thirty-one (33.33%) had osteoporosis, 56 (60.21%) osteopenia, whereas 36 (38.7%) had prior or existing fractures. Older participants had lower NTx levels, and females had higher NTx levels, albeit NS. A negative correlation was found between the T-score of the left hip and NTx levels (p = 0.015) but not of the right hip or lumbar spine. In multivariate analysis, NTx levels (p = 0.013) and FRAX (p = 0.001) were significantly associated with fractures. Patients with osteoporosis had higher NTx levels when compared to patients with osteopenia (p = 0.015). NTx at a cut-off value of 207.4 showed a sensitivity of 80.6% and a specificity of 56.1% for the diagnosis of previous fracture with an area under the curve (AUC) of 0.72 (95% CI: 0.61, 0.83). Conclusions: Elevated NTx levels were significantly associated with existing or prior fractures. Combining DXA scan and FRAX, with NTx testing, may provide a comprehensive approach to osteoporosis assessment and treatment. Further prospective studies are warranted to validate its clinical utility.