A Slight Decrease in the Serum Albumin Level Is Associated with the Rapid Progression of Kidney Dysfunction, Even within the Normal Range

OBJECTIVE: A low-normal albumin level is associated with a high risk of cardiovascular disease and mortality in the general population. However, the relationship between the serum albumin level and the future decline in the kidney function is unclear. We evaluated the effect of the serum albumin level on the decline in the kidney function in the general population. METHODS: The data used were from 11,000 participants in a voluntary health checkup program conducted between 1998 and 2006 in Japan. The primary outcome for the kidney function was a difference in the estimated glomerular filtration rate (ΔeGFR) of ≥3 mL/min/1.73 m(2)/year. The association of the risk of a decreased kidney function with the albumin level was determined using a logistic regression analysis. We fit separate multivariable logistic regressions for the serum albumin levels (g/dL) as a continuous variable and as categorical data, classified as ≤4.3 (n=2,530), 4.4-4.6 (n=5,427), and ≥4.7 (n=3,043). RESULTS: Of the 11,000 participants, 346 had a ΔeGFR/year of ≥3. Compared with the participants with albumin levels of ≥4.7 g/dL, the risk of a decline in the kidney function was higher not only in those with albumin levels of ≤4.3 g/dL [adjusted odds ratio (OR)=2.10, 95% confidence interval (CI): 1.20-2.93] but also in those with levels of 4.4-4.6 g/dL (adjusted OR=1.53, 95% CI: 1.14-2.05). CONCLUSION: A decreased albumin level is an independent risk factor for a rapid decline in the kidney function, even within the normal range.