Insights into cerumen and application in diagnostics: past, present and future prospective

Abstract

Cerumen or earwax is an emerging bio-fluid in clinical diagnosis that has been very little exploited during the past decades in spite of its high diagnostic potential. It is highly abundant in diagnostic biomarkers such as genetic material, lipids, proteins, chemical elements, internal and external metabolites (e.g. hormones, volatile organic compounds, amino acids, xenobiotics etc.) reaching earwax from the blood circulation. Thus, it is able to reflect not only physiology, pathophysiology of the human body but can also detect recent and long term exposure to environmental pollutants, without the need of invasive blood tests and in the same time overcoming many disadvantages faced by using other diagnostic biological fluids. This review discusses the biology, functions, chemistry of earwax, past and current approaches for the study of its chemical composition, emphasizing how a detected variation in its composition can offer information of high clinical value, which can be useful in diagnosis of many diseases such as metabolic disorders and tumours as well as in forensic applications. It also presents details about techniques of sample collection, storage, and analysis. Moreover, it highlights concerns about the use of earwax for diagnostic purposes, which should be addressed to make earwax diagnostics a reality in the future.

Anatomy and Development of the Mammalian External Auditory Canal: Implications for Understanding Canal Disease and Deformity

“…Serous secretions and sebum from the cerumen glands mix with sloughed keratinized squames. A natural lubricant, ear wax aids the self-cleaning function of the ear canal, and is thought to have antimicrobial properties ( Shokry and Filho, 2017 ). Interestingly, a little like tongue rolling ability, ear wax type is a dimorphic trait.…”

Identification of Altered miRNAs in Cerumen of Dogs Affected by Otitis Externa

“…In addition to its biological function, cerumen has gained interest in the clinical setting as a potential source of biomarkers (14). Cerumen composition indeed reflects the pathophysiological status of the patient, containing lipids, proteins, and metabolites derived from blood (14).…”

“…In addition to its biological function, cerumen has gained interest in the clinical setting as a potential source of biomarkers (14). Cerumen composition indeed reflects the pathophysiological status of the patient, containing lipids, proteins, and metabolites derived from blood (14). Although the amount and the variation of texture and color of cerumen during ear diseases have been accurately described in dogs (15), the active protective role of cerumen in the development of immunity during otitis externa is yet to be determined.…”

The Assessment of antimicrobial activity of cerumen (earwax) and antibiotics against pathogenic bacteria isolated from ear pus samples

“…It picks up discarded cells, ear follicles and may contain dust or other debris, but the resulting compound forms earwax or cerumen. 6 There are two different types of genetically determined earwax such as wet type and dry type. The dry type is most common in Asians and Native Americans and has a grey brownish colour while the wet type can be found in Caucasians and Africians and has a brown or dark colour.…”