Effect of Lipid Profile Parameters on Noise Induced Hearing Loss.

Background: Noise induced hearing loss (NIHL) is an irreversible occupational disease among industrial workers. Recent studies have reported that changes in some metabolic factors such as the serum level of sugar and lipids might have a role in suffering from NIHL among workers exposed to noise. We designed this study to assess the association between lipid profile changes and NIHL occurrence among noise-exposed workers.

Methods: This case-control study has been conducted according to noise-exposed workers registry data in one of the Iranian automobile factories between 2007 and 2017. We classified study workers into the NIHL and control groups. We assessed the impact of lipid profile parameters across the study groups using the independent samples t-test, chi-square, and regression.

Results: The mean serum level of cholesterol was significantly higher in the NIHL group than in workers of the control group (215.27 ± 60.30 vs 204.49 ± 63.69 mg/dL; P = 0.041). Moreover, the serum level of HDL was significantly lower in workers in the NIHL group compared with the control group (35.21 ± 6.87 vs 37.43 ± 7.28 mg/dL; P < 0.001). Although other lipid profile parameters (LDL, TG, LDL/HDL ratio) were higher among workers of the NIHL group, their differences were not significant.

Conclusion: A cholesterol level lower than 200 mg/dL is known as a protective factor and an HDL level lower than 40 mg/dL is an NIHL risk factor. More attention should be paid to controlling serum levels of cholesterol and HDL.