Exercise proteinuria and hematuria: current knowledge and future directions.

INTRODUCTION: Transient proteinuria and hematuria are apparently benign sequelae of intensive physical activity. However, there is a need to establish underlying causes and reasons for progression to chronic renal damage, as well as effects of training in healthy individuals and in those with microalbuminuria. EVIDENCE ACQUISITION: The Ovid/Health Star database was searched from 1994 to November 2014. Terms for the kidneys (adverse effects, blood supply, epidemiology, injuries, pathology, physiology and secretion) and proteinuria (classification, complications, epidemiology, etiology, mortality, physiopathology, prevention and control) with terms related to physical activity (physical activity/motor activity, exercise/exercise therapy, fitness/physical fitness, physical education/physical education and training, and rehabilitation). EVIDENCE SYNTHESIS: Review of 519 abstracts yielded 194 relevant hits, supplemented by 70 items from other sources. This material related to both healthy adults (125 items) and renal disease (139 items). The prevalence (18-100%) and duration (1-6 days) of exercise proteinuria varied widely, with risks affected by exercise intensity, posture, age, heat load, altitude and disease. Moderate training reduced exercise proteinuria in healthy individuals and in chronic renal disease. Factors contributing to exercise proteinuria may include vascular changes, hypoxia, lactate accumulation, oxidant stress, hormonal changes and sepsis. Exercise hematuria is frequent; some potential causes are similar to those for proteinuria, but foot-strike and bladder trauma are probably more important. Progression to permanent renal damage is rare.
CONCLUSIONS: Exercise proteinuria and hematuria are generally transient. However, there remains a need to clarify causation and factors leading to permanent renal damage.