Ricong Xu*, Zhijian Li**, Ying Liao1, Tao Cao*, Yi Xu1, Qijun Wan*,#
*The First Affiliated Hospital of Shenzhen University, Health Science Center; Department of Nephrology, Shenzhen Second People's Hospital, Shenzhen 518035, China - **Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510080, China; Key Laboratory of Nephrology, Ministry of Health, Guangzhou, Guangdong, 510080, China
Introduction: Limited clinical studies have investigated the relationship between serum albumin and IgA nephropathy (IgAN), while the increased urinary excretion of albumin, albuminuria, has been regarded as an essential prognostic marker in various kidney diseases. Interstitial fibrosis and tubular atrophy (IFTA) has been strongly confirmed as an independent predictor for renal outcomes in patients with IgAN. However, the relationship between serum albumin and IFTA for the disease is unclear.
Case Presentation: We retrospectively analyzed patients with biopsy-proven primary IgA nephropathy from January 1, 2011 to December 31, 2017 in Shenzhen Second People's Hospital, demographic and clinicopathologic data were obtained from our database. All the participants were divided into three groups according to the tertiles of serum albumin. After adjusting for age, gender, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), estimated glomerular filtration rate (eGFR), high-sensitivity C-reactive protein (hs-CRP), hemoglobin, urea acid, total cholesterol, triglyceride, proteinuria, a non-linear relationship between serum albumin and interstitial fibrosis and tubular atrophy was detected, and the inflection point was 33 g/L. The odds ratios and the 95% confidence intervals on the left and right sides of the inflection point were 1.25 (1.06-1.47) and 0.93 (0.86-1.02), respectively. Subgroup analysis showed, in patients with nephrotic range proteinuria, serum albumin had a positive correlation with interstitial fibrosis and tubular atrophy (OR 1.16, 95% CI 1.05-1.27), while negative correlations were identified in patients without anemia (OR 0.91, 95% CI 0.88-0.95) and hypercholesterolemia (OR 0.86, 95% CI 0.81-0.91), and the interaction p values were less than 0.05.
Conclusion: The relationship between serum albumin and interstitial fibrosis and tubular atrophy was non-linear. Serum albumin was positively correlated with interstitial fibrosis and tubular atrophy when albumin was less than 33 g/L. Further, the correlation between albumin and interstitial fibrosis and tubular atrophy was likely to vary by the levels of proteinuria, hemoglobin as well as total cholesterol. These findings implied that early intervention of hypoalbuminemia might do good for IgA nephropathy patients against renal tubular interstitial lesions, and avoiding of anemia, hypercholesterolemia as well as nephrotic range proteinuria in these patients might strengthen this effect as well.
IgA nephropathy (IgAN), interstitial fibrosis and tubular atrophy (IFTA), serum albumin.