Biomarkers of disease in human nails: a comprehensive review

Abstract

Diagnostic, monitoring, response, predictive, risk and prognostic biomarkers of disease are all widely studied, for the most part in biological fluids or tissues, but with steadily growing interest in alternative matrices of which nails are an example. Here we comprehensively review studies dealing with molecular or elemental biomarkers of disease, as opposed to semiological, pharmacological, toxicological or biomonitoring studies.Nails have a long history of use in medicine as indicators of pathological processes, and have also been used extensively as a matrix for monitoring exposure to environmental pollution.Nail clippings are simple to collect non-invasively, to transport and to store, and the matrix itself is relatively stable. Nails incorporate, and are influenced by, circulating molecules and elements over their several months' of growth, and it is widely held that markers of biological processes thus included will remain in the nail, even when their levels in blood have declined.They thus offer the possibility, not only of looking back into a subject's metabolic history, but also of studying biomarkers of processes that operate over a longer time scale such as the posttransational modification of proteins.Reports on ungual biomarkers of metabolic and endocrine diseases, cancer, and psychological and neurological disorders will be presented, and an overview of the sampling and analytical techniques provided.

Rhinoceros horn mineral and metal concentrations vary by sample location, depth, and color

“…Furthermore, since many minerals can be measured in rhino horn, it may provide biomarkers of health beyond IOD. The associations between human hair or nail biomarkers and disease have been studied for years 41 , 42 . For example, interesting relationships between human nail Se, furosine, and glycated proteins and type 2 diabetes have been reported 41 and may likewise be of interest in rhinos since ex situ conditions appear to contribute to decreased insulin sensitivity 43 .…”

Minimally invasive biomarkers in human and non‐human primate evolutionary biology: Tools for understanding variation and adaptation

“…There are several promising biospecimen types to consider. Nail clippings, for example, are now established in several fields as viable for the measurement of hormones and other analytes (Jaramillo Ortiz et al, 2021 ), most notably cortisol (Fischer et al, 2020 ). Recent work in HEB has shown the promise of this approach, demonstrating that fingernail cortisol levels among forager children of the Congo Basin are inversely correlated with measures of experienced fathering quality (Gettler et al, 2021 ).…”