Effect of zinc sulfate on sensorineural olfactory disorder.

We administered zinc sulfate to patients with sensorineural (post-viral, post-traumatic, or unknown aetiology) olfactory disorder and examined its effects. The patients were divided into three groups by method of treatment: zinc sulfate only, combination of zinc sulfate and the usual therapy, or the usual therapy. For disorders of post-viral and unknown aetiologies, there were no significant differences in improvement among the three groups. However, for post-traumatic olfactory disorder, the zinc sulfate groups had significantly higher improvement rates than did the group that received the usual therapy. The difference between post-traumatic and post-viral olfactory disorders in the effect of zinc sulfate therapy appeared to depend on the pathology of the associated lesions. In cases of post-traumatic olfactory disorder, regenerative capacity is retained in the olfactory epithelium because the blast cells of olfactory receptor cells remain intact. However, for post-viral olfactory disorder, the lack of olfactory receptor cells and blast cells due to viral infection results in loss of regenerative capacity. We also determined pre-treatment serum zinc concentrations in those patients who planned to be treated with zinc sulfate. Pre-treatment serum zinc concentration was not significantly related to improvement rates.