Schubert et al conducted a longitudinal study using data from the Epidemiology of Hearing Loss Study to evaluate the association between the incidence of hearing impairment (HI) and cystatin C, both as an independent biomarker and as an estimate for glomerular filtration rate (eGFRCysC). The authors found that low eGFRCysC was significantly associated with increased 20-year cumulative incidence of HI, though cystatin C alone was not. They conclude that reduced kidney function, as estimated by cystatin C, may be associated with increased risk of HI. Monsell provides an Invited Commentary.