The effect of high-dose Levothyroxine on hearing in patients operated for thyroid cancer

Objective The aim of this study is to investigate the relationship between the use of high doses of levothyroxine (L-T4) and hearing loss in patients who have undergone surgery for thyroid cancer.

Material method After total thyroidectomy for thyroid cancer, patients were divided into two groups according to L-T4 dose below 150 µg and above 150 µg.

Demographic characteristics, postoperative duration, radioactive iodine treatment, bone densitometry scans with LDxa and FDxa, and right and left ear hearing levels were statistically compared in both groups.

Results The study included 62 patients, 85.5% ( n  = 53) of whom were female, with a mean age of 48.8 ± 11.7 years.

While 56.45% ( n  = 35) of the patients were taking L-T4 below 150 µg 43.55% ( n  = 27) were taking L-T4 above 150 µg.

The mean postoperative duration of the participants was 4.1 ± 2.7 years, osteopenic 30.7% and osteoporotic 16.13% according to LDxa, osteopenic 29.0% and osteoporotic 1.6% according to FDxa.

Hearing loss in both right and left ears was 41.9% and sensorineural hearing loss in both ears was 22.6%.

Age, LDxa, FDxa, hearing loss in the right and left ear were found to be significantly different in the two groups above and below 150 µg according to the dose of L-T4 used ( p  < 0.05).

However, no differences were found according to sex, height, weight, body mass index, postoperative period, or radioactive iodine treatment ( p  > 0.05).

Both osteopenia and osteoporosis, as well as hearing loss in both the right and left ear, were significantly higher in the group taking L-T4 150 µg or more ( p  < 0.05).

Conclusion In our study, we found that patients taking 150 µg or more of L-T4 daily were more osteopenic and osteoporotic and had more hearing loss in both ears.