Association between serum 25-hydroxyvitamin D and albuminuria in Korean adolescents: evidence from a national survey.

OBJECTIVES

Albuminuria is an established early marker of kidney damage and a strong predictor of cardiovascular risk. This study aimed to investigate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and urinary albumin-to-creatinine ratio (ACR) among Korean adolescents.

METHODS

In this cross-sectional analysis of the 2011-2014 Korea National Health and Nutrition Examination Survey (KNHANES), we assessed adolescents aged 10-19 years. Log-transformed urinary ACR was regressed on serum 25(OH)D using linear regression, adjusting for age, sex, BMI category, glycemic status, and blood pressure. Subgroup analyses were conducted according to vitamin D deficiency (< 20 ng/mL vs. ≥ 20 ng/mL).

RESULTS

This analysis included 2,109 adolescents with a mean age of 14.2 ± 2.8 years. The mean serum 25(OH)D concentration was 16.5 ± 5.2 ng/mL, and the mean urinary ACR was 0.78 ± 2.29 mg/g Cr. Linear regression analysis revealed a significant inverse association between serum 25(OH)D levels and log-transformed ACR (crude regression coefficient: -0.0242; 95% CI: -0.0347 to -0.0137). This inverse association remained statistically significant after adjusting for age, sex, body mass index category, glycemic status, and blood pressure (adjusted regression coefficient: -0.0193; 95% CI: -0.0303 to -0.0083). The inverse association was stronger among participants with vitamin D deficiency (serum 25(OH)D < 20 ng/mL), with an adjusted regression coefficient of -0.0378 (95% CI: -0.0567 to -0.0189).

CONCLUSION

Serum vitamin D levels were inversely associated with albuminuria among Korean adolescents, independent of major confounding factors. The association was particularly pronounced among those with vitamin D deficiency, underscoring the potential role of vitamin D in early kidney health.