Association between phase angle and albuminuria in Korean adults aged 40 years or older: a cross-sectional study of the 9th Korea National Health and Nutrition Examination Survey (2022-2023).

BACKGROUND

Phase angle (PhA), derived from bioelectrical impedance analysis, reflects cellular health and membrane integrity and is reduced in chronic diseases. Albuminuria is an early marker of endothelial and microvascular injury and predicts renal and cardiovascular diseases. This study aimed to investigate the association between PhA and albuminuria in Korean adults aged 40 years or older.

METHODS

We conducted a cross-sectional analysis of data from the 9th Korea National Health and Nutrition Examination Survey (2022-2023). After excluding participants younger than 40 years of age, those with diabetes, elevated serum creatinine levels, and those with missing data, 3,283 adults (1,495 men and 1,788 women) were included. Whole-body PhA at 50 kHz was used as the independent variable. Albuminuria was defined as a urine albumin-to-creatinine ratio of ≥30 mg/g. Survey-weighted, sex-stratified multivariate logistic regression models were adjusted for age, lifetime smoking, drinking frequency in the previous year, hypertension status, body mass index, glycated hemoglobin, low- and high-density lipoprotein cholesterol, triglycerides, serum creatinine, blood urea nitrogen, high sensitivity C-reactive protein, and skeletal muscle mass index.

RESULTS

Albuminuria was identified in 7.0% of the participants (7.2% of men and 6.9% of women). In women, each 1° increase in PhA was associated with substantially lower odds of albuminuria (adjusted odds ratio, 0.47; 95% confidence interval, 0.26-0.86). In men, the relationship showed a J-shaped pattern, with the lowest risk at mid-range PhA values and a marked increase at higher values; both linear and quadratic PhA terms were significant.

CONCLUSION

In Korean adults, PhA showed sex-specific associations with albuminuria, with an inverse association in women and a J-shaped association in men. As a noninvasive and widely available measure, PhA could potentially serve as a supplementary tool for identifying individuals at risk for early renal microvascular injury.