Blood work which typically would consist of a CBC, differential and electrolytes along with an autoimmune panel are often normal and would not change initial clinical management if abnormal. The CT scan which is done to rule out central causes is not sensitive enough to pick up most cases of retrocochlear pathology. MRI scans should be considered instead. If verified to be sensorineural with audiometric testing, urgent treatment with steroid therapy can be initiated. There is no role for antiviral treatment, thrombolytics or vasoactive substances.
Sources:
Stachler RJ, et al. Clinical practice guideline: sudden hearing loss. Otolaryngol Head Neck Surg. 2012 Mar;146(3 Suppl):S1-35. PMID: 22383545.