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Kidney Function and Albuminuria Associated with Bone Mineral Density and Fracture Risk: The Tromsø and Trøndelag
Ingebjørg Tronstad1,2, Solfrid Romundstad2,3, Marit D Solbu4,5
1HUNT Research Centre, Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, NTNU - Norwegian University of Science and Technology, Levanger Norway.
Insights
Albuminuria exacerbates bone density loss and fracture risk in chronic kidney disease (CKD). Even mild CKD with albuminuria is linked to poorer bone health, highlighting the importance of monitoring both conditions.
Area of Science:
- Nephrology
- Endocrinology
- Geriatrics
Background:
- Chronic kidney disease (CKD) is linked to reduced bone mineral density and fractures, particularly in advanced stages.
- The impact of mild to moderate CKD and albuminuria on bone health remains less understood.
- Investigating the interplay between CKD stage, albuminuria, and skeletal complications is crucial.
Purpose of the Study:
- To determine if albuminuria modifies the relationship between CKD stage and bone mineral density.
- To assess the association between CKD stage, albuminuria, and the risk of major osteoporotic fractures.
- To clarify the role of albuminuria in bone health across different CKD severities.
Main Methods:
- Utilized data from the HUNT and Tromsø studies (n=31,341) with CKD classification by eGFR and albuminuria levels.
- Employed linear mixed models and Cox regression to analyze bone mineral density and fracture risk.
- Investigated effect modification using interaction terms and estimated contrasts between CKD-albuminuria categories.
Main Results:
- Bone mineral density was lower and fracture risk higher in advanced CKD (G3b/G4).
- Albuminuria (A2/A3) independently correlated with lower bone mineral density and increased fracture risk.
- In the presence of albuminuria, bone mineral density decreased progressively from CKD stage G3a, and fracture risk was consistently higher across advancing CKD stages.
Conclusions:
- Advanced CKD, especially with albuminuria, is associated with reduced bone mineral density.
- Fracture risk increases from CKD stage G3a and is generally higher with albuminuria.
- Albuminuria appears to be a significant factor in impaired bone health among CKD patients.
Background:
Reduced bone mineral density and fractures are well-established complications in advanced CKD, but the role of mild to moderate CKD and albuminuria remain unclear. We assessed whether albuminuria modifies the association between CKD stage and bone mineral density and risk of major osteoporotic fractures.
Methods:
Participants from the HUNT and Tromsø studies (n=31,341) provided data on CKD (classified by eGFR G1 (≥90), G2 (60-89), G3a (45-59), and G3b/G4 (<45 mL/min/1.73 m2)), albuminuria (defined by albumin-creatinine ratio: A1 (<30 mg/g) and A2/A3 (≥30 mg/g)) and fractures. We estimated mean bone mineral density differences and hazard ratios (HRs) using linear mixed models and Cox regression. Effect modification was assessed using an interaction term and Wald test. Linear combinations were used to estimate pairwise contrasts between CKD-albuminuria categories (reference: CKD G1 and albuminuria A1), and within CKD stages.
Results:
Compared with G1, bone mineral density was modestly lower and fracture risk was highest in G3b/G4 (HR 1.40; 95% confidence interval [CI]: 1.12 to 1.74). Albuminuria (A2/A3) was associated with both lower bone mineral density and slightly higher fracture risk compared with A1, independent of eGFR. Patterns differed by albuminuria category: In A1, bone mineral density remained stable across CKD stages, whereas in A2/A3 it was progressively lower from G3a onward. Fracture risk increased with CKD severity in both albuminuria categories and was consistently higher in A2/A3 across advancing CKD stages. In G3b/G4, HRs were 1.27 (CI: 0.96 to 1.68) in A1 and 1.58 (CI: 1.07 to 2.36) in A2/A3.
Conclusions:
Lower bone mineral density was observed in advanced CKD with albuminuria. Fracture risk increased from CKD stage G3a and tended to be higher in the presence of albuminuria, indicating an association between albuminuria and impaired bone health.
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