Abstract: SA-PO0568
Higher Normal-Range Serum Phosphorus Is Inversely Associated with Albuminuria in US Adults with Preserved Kidney Function
Session Information
- Bones, Stones, and Mineral Metabolism: Research and Cases
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 502 Bone and Mineral Metabolism: Clinical
Author
- Ashkar, Ziad Maurice, Ochsner Lafayette General, Lafayette, Louisiana, United States
Background
Serum phosphorus, even within the normal reference range, activates the FGF-23–klotho axis. Whether normal-range phosphorus predicts albuminuria — a marker of early glomerular and tubular injury — across the eGFR spectrum has not been characterized in a nationally representative U.S. population
Methods
Cross-sectional analysis of NHANES 2015–2018 (n=9,419 adults, eGFR ≥15 mL/min). Serum phosphorus was analyzed continuously and in quartiles (Q1 ≤3.30, Q2 3.30–3.60, Q3 3.60–4.00, Q4 >4.00 mg/dL). Survey-weighted logistic and linear regression with sandwich variance estimators were conducted, stratified by eGFR category, with albuminuria (UACR ≥30 mg/g) and log-transformed UACR as outcomes of interest. Sensitivity analyses included additional adjustment for dietary protein intake.
Results
Albuminuria prevalence decreased from Q1 (11.1%) to Q4 (7.7%) in the full sample (p-trend=0.043). In eGFR ≥90 (n=5,942), each 1-SD phosphorus increase was associated with lower albuminuria odds (OR 0.82, 95% CI 0.72–0.95, p=0.007) after adjustment for available confounders, and with lower log-UACR (β −0.055, p=0.001). Q4 vs. Q1: OR 0.63 (95% CI 0.42–0.94, p=0.024). Formal phosphorus×eGFR interaction was non-significant (spline p=0.633). Results were consistent across sex strata and after adjustment for dietary phosphorus and dietary protein.
Conclusion
In U.S. adults with preserved kidney function, higher normal-range serum phosphorus is inversely associated with albuminuria after multivariate adjustment. This cross-sectional inverse pattern is robust to sensitivity analyses but does not permit causal inference. These findings are hypothesis-generating and require prospective confirmation incorporating FGF-23, klotho, and urinary phosphate biomarkers before any clinical inference is warranted.
Figure 1 display stage-specific adjusted ORs. The inverse association was significant in G1 (OR 0.82, p=0.007) and G2 (OR 0.82, p=0.020), with consistent β coefficients for log-UACR. In G3a (OR 0.91, p=0.49) and G3b–G4 (OR 0.92, p=0.62), the association was attenuated and non-significant. In the pooled full-spectrum model, the inverse association remained significant (OR 0.83, 95% CI 0.75–0.92, p<0.001)