Effects of hemodialysis on hearing threshold.

71 chronic renal failure patients undergoing long-term hemodialysis were evaluated for the effects of a dialysis event on hearing function. Osmotically active serum constituents were examined for relationship to fluctuating hearing threshold levels. Reliabiliity of hearing levels was found to be better in those patients tested without an intervening dialysis event. Those patients tested before and after hemodialysis demonstrated greater hearing fluctuation than those patients evaluated between dialysis events. This threshold fluctuation was unrelated to serum urea nitrogen, creatinine, K+, Na+, Ca++, or glucose. It was concluded that hearing test reliability in dialyzing renal patients is resonably good, but test results are likely to be more consistent if testing is accomplished a number of hour after a given dialysis event. Contrary to a number of reports in the recent literature, no direct relationship between hearing level fluctuation and fluctuation in individual osmotically active serum constituents appeared to be present.