Longitudinal bone loss in patients with stage 3 CKD: a study based on densitometry and HR-pQCT.

UNLABELLED: In a 1-year longitudinal study of 34 patients with stage 3 CKD and stable bone turnover markers there was no deterioration of bony quality. However, HR-pQCT identified impaired bone density in 73.5% of cases at baseline, which was undetected by DXA. Findings suggest early skeletal involvement despite stable renal function. PURPOSE: It has been postulated that chronic kidney disease (CKD) is associated with bone loss. However, prospective data are limited, and it remains unclear whether bone loss or microarchitecture chances occurs in the early stages of CKD with stable renal function. METHODS: In this longitudinal cohort study, patients with stage 3 CKD underwent dual-energy X-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT), with reassessment after 1 year. Bone biomarkers, including alkaline phosphatase, intact parathyroid hormone (iPTH), intact fibroblast growth factor-23 (iFGF-23), total procollagen type 1 N-terminal propeptide (tP1NP), and β-isomerized C-terminal telopeptide of type I collagen -I (β-CTX-I) were also measured. RESULTS: Thirty-four patients were included (51 ± 3 years, 44% men). Bone turnover markers remained stable during follow-up. Osteopenia and/or osteoporosis at one or more sites was found in 45.5% of participants. Low bone mineral density (BMD), T-score < -1, was observed in 32.3% (lumbar spine), 29.4% (total hip), 14.7% (1/3 distal radius), and 26.5% (ultradistal radius). HR-pQCT revealed impaired BMD in at least one site (tibia or radius) in 73.5% of cases. Renal function remained stable during follow-up, with no significant changes in bone biomarkers. DXA showed a slight but significant decline in T-scores at the total hip and 1/3 distal radius, whereas HR-pQCT parameters remained unchanged. CONCLUSION: In patients with stage 3 CKD and stable renal function, bone microarchitecture identified impaired BMD not fully detected by DXA. Over 1 year, however, only minimal changes in bone parameters were observed.