Purpose: Vigorous exercise increases urine protein excretion. However, whether exercise increases urine albumin enough to reach the threshold for microalbuminuria (2.8 and 2.0 mg/mmol creatinine in women and men respectively) is uncertain. Furthermore, the duration of such albuminuria is unknown. We aimed to estimate the prevalence and duration of exercise induced microalbuminuria in normal healthy volunteers.
Methods: Thirty normal subjects provided a urine sample, then exercised to maximal heart rate, or exhaustion, using the standard Bruce Treadmill protocol. Further urine samples were collected within 15 min of completing exercise, and 24 and 48 hr later. Urine creatinine was measured by the Jaffé method and albumin via immunoturbidometry.
Results: Baseline urine albumin: creatinine ratio (A/C) was 0.5 +/- 0.3 (SD) in women (n=14) and 0.4 +/- 0.1 mg/mmol in men (n=16). Immediately after exercise A/C increased to 5.6 +/- 9.7 (in women) and 7.6 +/- 17.6 (in men). Twelve of 30 subjects reached the threshold for microalbuminuria and 2 that for macroalbuminuria. By 24 hr all had returned to baseline and there was no further change at 48 hours.
Conclusions: A short period, 15-20 min, of maximal exercise leads to A/C ratios above the microalbuminuria threshold in a substantial proportion of normal subjects. Physicians should not measure urine albumin in patients who give a history of such activity in the past 24 hr.