Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (782 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The thin, horny plates that cover the dorsal surfaces of the distal phalanges of the fingers and toes of primates.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Nail; Fingernails; Fingernail; Toenails; Toenail.
Where it fits in the MeSH classification
- Broader topics
- Integumentary System
Research landscape
PubMed indexes 9,819 records tagged with the MeSH heading “Nails” (counts retrieved 2026-10-31). 1,832 of them (18.7%) were published from 2020 onward, and the busiest period so far is through 1999 with 4,191 records.
Reviews account for 912 records (9.3%) and meta-analyses for 32. Randomized controlled trials number 143 (1.5%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 4,191 |
| 2000-2009 | 1,435 |
| 2010-2019 | 2,361 |
| 2020 onward | 1,832 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 912 | 9.3% |
| Meta-analyses | 32 | 0.3% |
| Randomized controlled trials | 143 | 1.5% |
Method: PubMed query "Nails"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated? | 2015 | Review article Design not recorded in structured metadata | 111 | cc by PMID 26421308 · DOI · PMC4569783 |
| Selenium and Prostate Cancer: Analysis of Individual Participant Data From Fifteen Prospective Studies | 2016 | Research article Design not recorded in structured metadata | 33 | cc by PMID 27385803 · DOI · PMC5241899 |
| An investigation of how fungal infection influences drug penetration through onychomycosis patient's nail plates | 2016 | Research article Design not recorded in structured metadata | 32 | cc by PMID 26969264 · DOI · PMC4827374 |
| Comparison of artificial intelligence and rheumatologists in nailfold capillaroscopic evaluation | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42138864 · DOI · PMC13167051 |
Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated? [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Video nailfold capillaroscopy (NFC), considered as an extension of the widefield technique, allows a more accurate measuring and storing of capillary data and a better defining, analyzing, and quantifying of capillary abnormalities.
- Closing excerpt
- This review focuses on the manner of performing video nailfold capillaroscopy and on a common approach for measuring capillary dimensions in fingers and toes.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (137 words)
Video nailfold capillaroscopy (NFC), considered as an extension of the widefield technique, allows a more accurate measuring and storing of capillary data and a better defining, analyzing, and quantifying of capillary abnormalities. Capillaroscopic study is often performed on the patients suspected of having microcirculation problems such as Raynaud's phenomenon as the main indication for nailfold capillaroscopy. Capillaroscopic findings based on microcirculation studies can provide useful information in the fields of pathophysiology, differential diagnosis, and monitoring therapy. Nailfold capillaroscopy provides a vital assessment in clinical practices and research; for example, its reputation in the early diagnosis of systemic sclerosis is well established and it is also used as a classification criterion in this regard. This review focuses on the manner of performing video nailfold capillaroscopy and on a common approach for measuring capillary dimensions in fingers and toes.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 26421308 · DOI · PMC4569783
Selenium and Prostate Cancer: Analysis of Individual Participant Data From Fifteen Prospective Studies [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundSome observational studies suggest that a higher selenium status is associated with a lower risk of prostate cancer but have been generally too small to provide precise estimates of associations, particularly by disease stage and grade.
- Closing excerpt
- Both blood and nail selenium concentrations are associated with a reduced risk of aggressive disease, which warrants further investigation.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (227 words)
BackgroundSome observational studies suggest that a higher selenium status is associated with a lower risk of prostate cancer but have been generally too small to provide precise estimates of associations, particularly by disease stage and grade.MethodsCollaborating investigators from 15 prospective studies provided individual-participant records (from predominantly men of white European ancestry) on blood or toenail selenium concentrations and prostate cancer risk. Odds ratios of prostate cancer by selenium concentration were estimated using multivariable-adjusted conditional logistic regression. All statistical tests were two-sided.ResultsBlood selenium was not associated with the risk of total prostate cancer (multivariable-adjusted odds ratio [OR] per 80 percentile increase = 1.01, 95% confidence interval [CI] = 0.83 to 1.23, based on 4527 case patients and 6021 control subjects). However, there was heterogeneity by disease aggressiveness (ie, advanced stage and/or prostate cancer death, Pheterogeneity = .01), with high blood selenium associated with a lower risk of aggressive disease (OR = 0.43, 95% CI = 0.21 to 0.87) but not with nonaggressive disease. Nail selenium was inversely associated with total prostate cancer (OR = 0.29, 95% CI = 0.22 to 0.40, Ptrend ConclusionsNail, but not blood, selenium concentration is inversely associated with risk of total prostate cancer, possibly because nails are a more reliable marker of long-term selenium exposure. Both blood and nail selenium concentrations are associated with a reduced risk of aggressive disease, which warrants further investigation.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 27385803 · DOI · PMC5241899
An investigation of how fungal infection influences drug penetration through onychomycosis patient's nail plates [3]
Abstract reading summary — source excerpts
- Opening excerpt
- The treatment of onychomycosis remains problematic even though there are several potent antifungal agents available for patient use.
- Closing excerpt
- Therefore, in order to exploit the structural changes induced by nail fungal infection it would be beneficial to develop a small molecular weight, hydrophilic antifungal agent, which exhibits low levels of keratin binding.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (276 words)
The treatment of onychomycosis remains problematic even though there are several potent antifungal agents available for patient use. The aim of this investigation was to understand whether the structural modifications that arise when a patient's nail become infected plates influences the permeation of drugs into the nail following topical application. It was hoped that through improving understanding of the nail barrier in the diseased state, the development of more effective topical treatments for onychomycosis could be facilitated. The permeation of three compounds with differing hydrophobicities, caffeine, terbinafine and amorolfine (clogD at pH 7.4 of -0.55, 3.72 and 4.49 respectively), was assessed across both healthy and onychomycosis infected, full thickness, human nail plate sections. Transonychial water loss (TOWL) measurements performed on the healthy and diseased nails supported previous observations that the nail behaves like a porous barrier given the lack of correlation between TOWL values with the thicker, diseased nails. The flux of the more hydrophilic caffeine was twofold greater across diseased in comparison with the healthy nails, whilst the hydrophobic molecules terbinafine and amorolfine showed no statistically significant change in their nail penetration rates. Caffeine flux across the nail was found to correlate with the TOWL measurements, though no correlation existed for the more hydrophobic drugs. These data supported the notion that the nail pores, opened up by the infection, facilitated the passage of hydrophilic molecules, whilst the keratin binding of hydrophobic molecules meant that their transport through the nail plate was unchanged. Therefore, in order to exploit the structural changes induced by nail fungal infection it would be beneficial to develop a small molecular weight, hydrophilic antifungal agent, which exhibits low levels of keratin binding.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 26969264 · DOI · PMC4827374
Comparison of artificial intelligence and rheumatologists in nailfold capillaroscopic evaluation [4]
Abstract reading summary — source excerpts
- Opening excerpt
- ObjectiveThe aim of this study was to evaluate the diagnostic accuracy of a pretrained Vision Transformer model on nailfold capillaroscopy images, comparing its performance to that of expert rheumatologists.
- Closing excerpt
- Accuracy and interrater agreement were calculated.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (142 words)
ObjectiveThe aim of this study was to evaluate the diagnostic accuracy of a pretrained Vision Transformer model on nailfold capillaroscopy images, comparing its performance to that of expert rheumatologists.MethodsWe retrospectively analyzed 104 anonymized images (23 normal, 81 pathological) from publicly available datasets. The pretrained Vision Transformer model was applied without fine-tuning. Two rheumatologists independently assessed the same image set. Accuracy and interrater agreement were calculated.ResultsThe AI model produced 0% clinical applicability, failing to generate meaningful classifications. In contrast, the consensus of two rheumatologists achieved the highest diagnostic performance, with 94.2% accuracy and a Cohen's Kappa of 0.827. Individual rheumatologist evaluations yielded comparatively lower accuracy and agreement.ConclusionWe retrospectively analyzed X anonymized images (XX normal, XX pathological) from publicly available datasets. The pretrained Vision Transformer model was applied without fine-tuning. Two rheumatologists independently assessed the same image set. Accuracy and interrater agreement were calculated.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42138864 · DOI · PMC13167051
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Standardisation of nailfold capillaroscopy for the assessment of patients with Raynaud's phenomenon and systemic sclerosis [5]
- Research article Measures of psoriatic arthritis: Tender and Swollen Joint Assessment, Psoriasis Area and Severity Index (PASI), Nail Psoriasis Severity Index (NAPSI), Modified Nail Psoriasis Severity Index (mNAPSI), Mander/Newcastle Enthesitis Index (MEI), Leeds Enthesitis Index (LEI), Spondyloarthritis Research Consortium of Canada (SPARCC), Maastricht Ankylosing Spondylitis Enthesis Score (MASES), Leeds Dactylitis Index (LDI), Patient Global for Psoriatic Arthritis, Dermatology Life Quality Index (DLQI), Psoriatic Arthritis Quality of Life (PsAQOL), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), Psoriatic Arthritis Response Criteria (PsARC), Psoriatic Arthritis Joint Activity Index (PsAJAI), Disease Activity in Psoriatic Arthritis (DAPSA), and Composite Psoriatic Disease Activity Index (CPDAI) [6]
- Research article Nails and fungi [7]
- Research article The nail as a musculoskeletal appendage--implications for an improved understanding of the link between psoriasis and arthritis [8]
- Research article Drugs in nails: physiology, pharmacokinetics and forensic toxicology [9]
- Research article Capillaroscopy [10]
References
- Etehad Tavakol M, Fatemi A, Karbalaie A, Emrani Z, Erlandsson BE. Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated?. . 2015. PMID 26421308 · DOI · PMC4569783
- Allen NE, Travis RC, Appleby PN, Albanes D, Barnett MJ, Black A, et al.. Selenium and Prostate Cancer: Analysis of Individual Participant Data From Fifteen Prospective Studies. . 2016. PMID 27385803 · DOI · PMC5241899
- McAuley WJ, Jones SA, Traynor MJ, Guesné S, Murdan S, Brown MB. An investigation of how fungal infection influences drug penetration through onychomycosis patient's nail plates. . 2016. PMID 26969264 · DOI · PMC4827374
- Çelik NÇ, Kılınç EA. Comparison of artificial intelligence and rheumatologists in nailfold capillaroscopic evaluation. . 2026. PMID 42138864 · DOI · PMC13167051
- Smith V, Herrick AL, Ingegnoli F, Damjanov N, De Angelis R, Denton CP, et al.. Standardisation of nailfold capillaroscopy for the assessment of patients with Raynaud's phenomenon and systemic sclerosis. Autoimmun Rev. 2020. PMID 31927087 · DOI
- Mease PJ. Measures of psoriatic arthritis: Tender and Swollen Joint Assessment, Psoriasis Area and Severity Index (PASI), Nail Psoriasis Severity Index (NAPSI), Modified Nail Psoriasis Severity Index (mNAPSI), Mander/Newcastle Enthesitis Index (MEI), Leeds Enthesitis Index (LEI), Spondyloarthritis Research Consortium of Canada (SPARCC), Maastricht Ankylosing Spondylitis Enthesis Score (MASES), Leeds Dactylitis Index (LDI), Patient Global for Psoriatic Arthritis, Dermatology Life Quality Index (DLQI), Psoriatic Arthritis Quality of Life (PsAQOL), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), Psoriatic Arthritis Response Criteria (PsARC), Psoriatic Arthritis Joint Activity Index (PsAJAI), Disease Activity in Psoriatic Arthritis (DAPSA), and Composite Psoriatic Disease Activity Index (CPDAI). Arthritis Care Res (Hoboken). 2011. PMID 22588772 · DOI
- English MP. Nails and fungi. Br J Dermatol. 1976. PMID 132961 · DOI
- McGonagle D, Tan AL, Benjamin M. The nail as a musculoskeletal appendage--implications for an improved understanding of the link between psoriasis and arthritis. Dermatology. 2009. PMID 19060455 · DOI
- Palmeri A, Pichini S, Pacifici R, Zuccaro P, Lopez A. Drugs in nails: physiology, pharmacokinetics and forensic toxicology. Clin Pharmacokinet. 2000. PMID 10709775 · DOI
- Cutolo M, Pizzorni C, Secchi ME, Sulli A. Capillaroscopy. Best Pract Res Clin Rheumatol. 2008. PMID 19041079 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.