Vitamin D supplementation added to standard corticosteroid therapy may improve hearing recovery at certain speech-related frequencies in patients with sudden sensorineural hearing loss and vitamin D deficiency, according to a randomized pilot study.
In a single-center, double-blind trial, researchers at Isfahan University of Medical Sciences in Iran assigned 40 patients with unilateral sudden sensorineural hearing loss of 45 days or less and serum vitamin D levels below 20 ng/mL to receive corticosteroids plus weekly vitamin D3 (50,000 IU) or corticosteroids plus placebo for 30 days. Audiometric testing was performed at baseline, day 10, and day 30, including pure-tone thresholds from 500 to 6000 Hz, speech reception threshold, and speech discrimination score.
Baseline characteristics, including age, sex, hearing thresholds, and laboratory measures, were similar between groups. Both groups showed improvement in hearing over 30 days, consistent with expected recovery during corticosteroid treatment.
Over the study period, patients who received vitamin D experienced greater improvement at 2000 Hz and 4000 Hz compared with those who received placebo, based on differences in change over time between groups. These frequencies fall within the range important for speech perception. At day 30, hearing thresholds at these frequencies were numerically lower in the vitamin D group than in the control group.
In contrast, no advantage for vitamin D was observed at lower frequencies (500 and 1000 Hz) or at 6000 Hz, where improvements were similar or greater in the control group. Improvements in speech reception threshold and speech discrimination score also did not differ between groups.
Vitamin D levels increased in the treatment group over the study period, while smaller increases were observed in the control group. Serum calcium and phosphorus levels remained stable, and no adverse events were reported.
The investigators identified improvement at 2000 Hz and 4000 Hz as the primary endpoint, citing the importance of these frequencies in auditory sensitivity. They noted that the human auditory system is particularly sensitive in the 2000–5000 Hz range, which may help explain the observed frequency-specific findings.
The study used block randomization and maintained blinding of both participants and investigators. Nonparametric statistical methods were used because the data were not normally distributed, and repeated-measures analyses were conducted to assess changes over time.
The authors acknowledged several limitations, including the small sample size, single-center design, and short follow-up period. They noted that the study could not distinguish the relative contributions of corticosteroids, spontaneous recovery, and vitamin D supplementation to hearing improvement.
“Future prospective studies with extended monitoring and increased sample sizes are warranted to confirm the potential additive effect of vitamin D in facilitating auditory recovery beyond the corticosteroid treatment window,” the investigators wrote.
The authors reported no financial disclosures.
Source: American Journal of Otolaryngology–Head and Neck Medicine and Surgery
