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Abstract: SA-OR067

Correlation of Albuminuria and Hypoalbuminemia with Area Under the Curve Levels of Mycophenolic Acid in Lupus Nephritis

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Pourafshar, Negiin, University of Virginia, Charlottesville, Virginia, United States
  • Wen, Xuerong, University of Rhode Island, Kingston, Rhode Island, United States
  • Mohandas, Rajesh, University of Florida, Gainesville, Florida, United States
  • Segal, Mark S., University of Florida, Gainesville, Florida, United States
Background

Mycophenolate mofetil (MMF) is the mainstay of therapy for lupus nephritis (LN). Studies have shown targeting an area under the curve (AUC) leads to better outcomes in these patients. Therefore, it is critical to identify factors modifying AUC of MMF. Mycophenolic acid (MPA) the active metabolite of MMF binds avidly to albumin. Since patients with lupus often have profound albuminuria and hypoalbuminemia, we hypothesized that it might influence MPA-AUC.

Methods

51 subjects with biopsy confirmed LN on 1500 mg of MMF twice daily, were included in this study. MPA levels were obtained at 0, 1, 2 and 4 hours. The MPA-AUC values calculated using the linear trapezoidal rule. Spearman correlations were used for correlations between urine albumin creatinine ratio (UACR), serum albumin and MPA-AUC.

Results

Subjects mean age was 33±13 years. The mean serum albumin was 3.3± 0.9 g/dL. 90 % of patients had albuminuria with a median of median of 874 mcg/mg [IQR: 365, 2150]. In univariate analysis there was a statistically significant correlation between AUC and UACR (Rho=-0.34, P=0.02) and serum albumin (Rho=0.48, P=0.004) ( Figure-1A and 1B). In multivariate analyses serum albumin remained an independent predictor of AUC when controlled for age and proteinuria [R2=0.21 p=0.03], but not for renal function[p=0.06]. Hypoalbuminuria was a predictor of AUC only for an eGFR > 60 ml/min/1.73 mt2.

Conclusion

Our results reveal that hypoalbuminemia is associated with lower therapeutic levels of MMF, particularly in those with normal renal function. Patients with hypoalbuminemia are more likely to have severe disease warranting higher doses of MMF. We will discuss the implications of these findings with regard to the monitoring of MMF-AUC to ensure adequate therapeutic doses in such patients.