Abstract
BACKGROUND: Exercise induced albuminuria (EiA) is elevated in patients with metabolic dysfunction and diabetes, and may serve as an early biomarker for endothelial dysfunction and "kidney reserve". However, the change in EiA levels over time and its interaction with metabolic dysfunction and glucose metabolism has never been studied. Therefore, we sought to determine EiA levels over time in a cohort of individuals attending a routine annual health survey. METHODS: We prospectively enrolled 412 patients attending an annual healthy survey at our Medical Center. We collected urine samples for albumin and creatinine measurements before and immediately after completing an exercise stress test, along with multiple physiologic and metabolic parameters. Participants returned to a second follow up visit after a mean follow up period of 3 years (± 1.7 SD). RESULTS: Patients with diagnosed diabetes and subjects with HbA1c ≥ 6.5% significantly increased their EiA over time (median [IQR] change between visits = 19.5 [- 10.4-56.1] vs. - 1.1 [- 12.7-4.9] (p = 0.049) for diabetics vs non-diabetics respectively). Moreover, a diabetes diagnosis was significantly associated with a high increase in EiA over time (top 10th percentile) even after adjusting for age, BMI, eGFR, METs, self-reported history of heart disease, systolic and diastolic blood pressure; OR = 4.4 (1.01-19.3 95% CI) (p = 0.049). Finally, elevated fasting blood glucose (≥ 100 mg/dl) was the strongest and only significant predictor for a greater increase in EiA over time after adjusting for all five metabolic syndrome components; blood glucose, waist circumference, blood triglycerides, HDL cholesterol, and BP criteria; OR = 4.0 (1.6-9.8 95% CI) (p < 0.01). CONCLUSIONS: Patients with diabetes and/or elevated fasting blood glucose increase their exercise-induced urinary albumin excretion over time. The ability of EiA to predict major clinical outcomes in patients with and without diabetes needs to be determined in future studies.