Recently it has been hypothesized that blood prestin concentration levels may reflect cochlear damage and thus serve as an easily measurable, early sensorineural hearing loss biomarker. This is a scoping review aiming to identify and critically appraise current evidence on prestin blood levels and their temporal variation in rodents and humans with normal hearing and with sensorineural hearing loss. This study was designed and held according to PRISMA Extension for Scoping Reviews (PRISMAScR) guidelines. With no limitation with regards to study type, animal and human studies focusing on prestin blood levels in normal hearing and in sensorineural hearing loss were sought in major databases such as Medline, Central. Scopus, PROSPERO and Clinicaltrials.gov. Results have been then hand-searched. A data charting form was developed including the parameters of interest. Seven studies focusing on measuring prestin blood levels by means of ELISA in rodents and human subjects with normal hearing and noise-induced, drug-induced, or idiopathic sudden hearing loss were found eligible and were included in the analysis. According to these proof-ofconcept studies, prestin can be detected in the circulation of subjects with no hearing
loss, however normal ranges remain unclear. After cochlear damage, blood prestin levels seem to initially rise and then return to near or below baseline. The degree of their change relates with subjects’ degree of hearing loss, damaged cochlear region and recovery. Prestin blood levels and their temporal variation seem to correlate with cochlear damage, however methodological weaknesses, such as small sample size, lack of detailed phenotyping, insufficient exclusion of confounding factors and short follow-up do not allow for robust conclusions. To conclude, current findings support the value of studying blood prestin levels in normal hearing and hearing loss, and highlight a need for larger scale longitudinal research.