Diagnostic performance of lumbar computed tomography Hounsfield unit thresholds for osteoporosis and osteopenia: a systematic review and meta-analysis.

Vertebral Hounsfield units (HU) measured on routine computed tomography (CT) have emerged as an accessible surrogate for bone mineral density (BMD), yet reported diagnostic thresholds vary widely. This meta-analysis aimed to define and test unified HU cut-offs for identifying osteopenia and osteoporosis. PubMed, EMBASE, MEDLINE, and Cochrane Library were searched to September 2025 for studies reporting vertebral HU referenced to dual-energy X-ray absorptiometry or quantitative CT. Continuous data were synthesised as standardised mean differences (SMD) and diagnostic accuracy using bivariate random-effects models. Reported thresholds were pooled to generate balanced, sensitivity-, and specificity-optimised cut-offs, tested through reconstructed 2 × 2 analyses. Twenty studies including 5016 patients met inclusion criteria. HU values were significantly lower in osteopenia and osteoporosis, with pooled SMD -2.78 for low BMD versus normal and -1.57 for osteoporosis versus non-osteoporotic bone (p < 0.001). Overall diagnostic performance was excellent (AUC 0.865; sensitivity 0.80; specificity 0.83). Pooled thresholds for osteopenia were 138.9 HU (balanced), 166.7 HU (high), and 111.2 HU (low); and for osteoporosis, 104.6 HU (balanced), 122.3 HU (high), and 86.8 HU (low). Decreasing HU was associated with stepwise increases in relative risk for low BMD. Vertebral HU strongly discriminate normal from low BMD, providing clinically applicable pooled thresholds for opportunistic CT-based screening and perioperative risk assessment. HU assessment could facilitate early detection and management of osteopenia and osteoporosis, particularly in surgical candidates.