ANALYSIS OF BLOOD-CHEMISTRY AND HEARING LEVELS IN A SAMPLE OF OLDER PERSONS

Objective: As part of an ongoing study of presbyacusis, the relationsh ip between blood chemistry levels and hearing levels was investigated. Previous reports often used small sets of blood chemistry measures, a nd results were inconclusive. This experiment examined hearing levels and 27 measures of blood chemistry using various univariate and multiv ariate statistical procedures. Design: Blood from 89 female and 128 ma le human subjects was collected. Subjects' ages ranged from 60 to 82 y r, and hearing levels ranged from normal to moderate/severe. Subjects with a history of middle ear disease were excluded. Electrolyte panel (Na, K, Cl, CO2, Ca, urea nitrogen, glucose, creatinine, and Mg), hema tology panel (WBC, RBC, Hgb, hematocrit, platelet, etc.), serum lipids (total cholesterol, low-density Lipoprotein [LDL], and high-density l ipoprotein [HDL]), immunoglobulins (IgG, IgA, IgM, and IgE), and thyro xine were analyzed using univariate and multivariate statistical proce dures. Results: Blood chemistry levels of most subjects were within no rmal ranges as defined by our laboratory. Correlation between blood ch emistry measures and pure-tone averages (PTAs) ranged from minimal to low. Results of factor analysis, discriminant analysis, and canonical analysis showed that combining blood chemistry measures from the same panel still could not predict PTA effectively. One exception to this w as a gender-specific effect of cholesterol. Bearing levels of women wi th high LDL/HDL ratios were 5 dB better than those of women with low L DL/HDL ratios. The comparable difference in men was only 1 dB. Conclus ion: Results suggest that blood chemistry measures that are primarily within the normal range have very little value in predicting pure-tone thresholds in older subjects.