Serum zinc-α2-glycoprotein and renal dysfunction in the general population: evidence from a 13-year cohort study

Zinc-α2-glycoprotein (ZAG) is an adipokine, which may act locally to regulate adipocyte metabolism. Downregulation of ZAG expression in obesity has been reported in obesity in both mice and humans. In contrast, other studies revealed that serum ZAG levels were positively associated with renal dysfunction. We investigated whether serum ZAG levels serve as a biomarker for renal impairment in a general population, both cross-sectionally and longitudinally.

A total of 223 residents (85 men and 138 women, mean age 67.1 ± 9.7 years old) underwent health examinations in 2011. Baseline fasting blood samples were collected, including measurement of serum ZAG. Participants were followed annually for 13 years.

Mean serum ZAG levels were 49.2 ± 13.7 μg/mL in males, and 41.7 ± 9.0 μg/mL in females. In univariate analysis, ZAG levels were significantly associated with male gender (p = 0.005), estimated glomerular filtration rate (eGFR p = 0.004, inversely), smoking habit (p = 0.031), and medication for hyperlipidemia (p = 0.024 inversely). In multiple logistic regression analysis, eGFR (p = 0.002, inversely), male gender (p = 0.003), and medication for hyperlipidemia (p = 0.038 inversely) remained significantly and independently associated with serum ZAG at baseline. During follow-up, 31 subjects developed chronic kidney diseases (CKD). However, baseline ZAG was not significantly associated with incident CKD over 13 years.

Serum ZAG levels were independently associated with renal function and may represent a novel biomarker of renal dysfunction in a general population. However, ZAG did not predict long-term CKD development.