Mortality-based definition of renal hyperfiltration in middle-aged men: a 35-year cohort from Finland.

The burden of increased eGFR within what is still considered normal eGFR category was highly underestimated. RHF's eGFR values had a U-shaped association with the risk of overall mortality. A more uniform consensual definition of RHF is needed, as higher to normal eGFR values that are not without consequences.