Brittle Nail Syndrome

Brittle nail syndrome is described as a constellation of nail abnormalities including onychorrhexis and/or onychoschizia that collectively contribute to increased fragility of the nail plate.[1, 2] Onychorrhexis is classically characterized by longitudinal ridging of the nail.[1] It has been cited as the ungual alteration most associated with patient perception of nail fragility.[3] Onychoschizia refers to lamellar splitting of the distal free edge portion of the nail plate.[4, 5] It may also include breaks of the lateral edges causing transverse splitting.[1] The diagnosis of brittle nail syndrome is established based on patient history and physical examination findings.

Images of onychorrhexis and onychoschizia are shown below.

Patients with brittle nail syndrome may frequently report that their nails are fragile, break easily, and have difficulty preserving length.[6] These nail abnormalities most typically affect the first three fingernails, and fingernails are more frequently affected than toenails.[3, 7] Not only are these nail features frequently a cosmetic concern for patients, but they can also cause significant pain and discomfort.[8]

Brittle nails can be of primary origin or develop secondary to an underlying condition.[9] Primary brittle nails are speculated to develop from the impairment of intercellular adhesive factors of the nail matrix or abnormalities in epidermal growth and keratinization. Brittle nails of secondary origin are typically linked to disordered keratinization from dermatologic disease or systemic disorders, such as endocrine, metabolic, or vascular abnormalities. Other precipitating factors for brittle nails include the repetitive wetting and drying of the hands, direct contact with chemicals (nail polish remover), trauma to the nail, and onychomycosis.[1]

Lifestyle factors

An increased risk for these nail abnormalities has been attributed to patients who manicure frequently, have occupations that require frequent handwashing or manipulation of the hands, and those who smoke tobacco.[1, 3]

Dermatologic diseases

Brittle nail syndrome has been associated with pemphigus vulgaris, psoriasis, eczema, lichen planus, alopecia areata, lichen striatus, scleroderma, Darier disease, discoid lupus erythematosus, and pityriasis rubra pilaris, among other conditions.[8, 10, 11]

Genetic diseases

It has been associated with numerous genodermatoses, including punctate palmoplantar keratoderma,[12] as well as congenital hemidysplasia with ichthyosiform erythroderma (or nevus) and limb defects (CHILD) syndrome, among many others.[13]

Systemic diseases

Onychorrhexis has been described in a wide variety of systemic diseases. It has been associated with liver disease (most commonly hepatitis C virus infection and cirrhosis),[3, 14] thyroid disease,[15] hypoparathyroidism,[16, 17] and chronic renal failure.[18]  It has also been associated with vascular diseases such as peripheral arterial disease, arteriosclerosis, microangiopathy, Raynaud disease, anemia, and polycythemia vera, as well as rheumatologic diseases such as gout, osteoarthritis, polyarteritis nodosa, rheumatoid arthritis, systemic lupus, and systemic sclerosis.[2, 14] Onychorrhexis can also be seen in graft versus host disease, sarcoidosis, primary systemic amyloidosis, and chronic immunosuppressed disorders such as severe combined immunodeficiency or AIDS.[14]

Mineral abnormalities

It has been associated with iron-deficiency anemia, arsenic poisoning, and zinc deficiency.[19]

Medication adverse effects

Brittle nails have been documented as an adverse effect of cancer therapy, including the Bruton tyrosine kinase inhibitor ibrutinib.[20] It has also been associated with azidothymidine, etanercept, hydroxyurea, itraconazole, and retinoid use.[14]

Frequency

Brittle nail syndrome affects approximately 20% of the population.[1] Onychoschizia is estimated to affect up to 35% of adult women specifically.[19] The prevalence rate of onychorrhexis alone has not been well-described in literature.

Sex

It is reported to have a notable increased prevalence in women.[1]

Age

It has an increased prevalence in adults older than 60 years.[1] Commonly referred to as a senile disorder, onychorrhexis has been associated with the age-related reduction in cholesterol sulfate within the nail over time.[21] The older age predilection may also be linked to the increased likelihood of impaired circulation and concurrent dermatologic or systemic disease with age.[4]

Race

Racial predilection of secondary onychorrhexis, if at all, may relate to the racial prevalence of the underlying disease.

The condition is not considered life-threatening. However, it can have a negative impact on quality of life and may impede with one’s daily activities and occupational responsibilities.[2] Idiopathic onychorrhexis is typically milder than onychorrhexis associated with inflammatory nail matrix diseases, such as lichen planus.[4] It can take a significant amount of time for patients to notice major clinical improvement, especially given the slow growth of the nail plate (range, 0.5-1.2 mm/wk),[22] and that many systemic conditions known to contribute to onychorrhexis are considered chronic.

Patients can help reduce damage to their nails and cuticles by using nail moisturizers and protecting their hands during daily tasks. Examples of nail moisturizers include petroleum jelly, lactic acid lotion, mineral oil, and urea cream. Nail moisturizers can be combined with lukewarm water soaks lasting 10-20 minutes. This increases hydration in the nail plate and improves the appearance of nail fragility. Wearing gloves for household chores and keeping hands dry help protect nails and cuticles. Wearing gloves also helps protect nails from harsh chemicals such as cleaners, solvents, and detergents.

Patient education articles include Nail Injuries, Finger Infection, and Onychomycosis.

Brittle nail syndrome classically develops gradually. Patients may disclose that their nail abnormalities were initially mild and worsened over time, causing additional pain or discomfort. The brittle nail findings may be associated with the onset of systemic disease, in certain cases.

Classic physical examination findings for onychorrhexis include shallow, parallel longitudinal furrows of the nail, often leading to distal longitudinal breakage along a furrow.[4] The furrows may even look as though they have been scratched by sandpaper.[5] The physical examination for onychoschizia likely will reveal transverse lamellar splitting of the distal free edge portion of the nail plate.[1]

The following grading system has been recommended to assess the severity of onychoschizia and onychorrhexis as components of brittle nail syndrome.[1]

Onychoschizia

Table 1. Proposed Score for Lamellar Splitting (Open Table in a new window)

Table 2. Proposed Score for Transverse Splitting (Open Table in a new window)

Onychorrhexis

Table 3. Proposed Score for Ridging (Open Table in a new window)

Table 4. Proposed Score for Longitudinal Splitting (Open Table in a new window)

This syndrome may cause significant pain and discomfort for patients, as well as increased risk of nail breakage owing to the nail plate fragility. It may also lead to functional impairment in severe cases.

A thorough review of systems (ROS) and a review of medical history and medications should direct subsequent workup to assess for potential systemic causes.

Examination of all 20 nails is recommended. Close inspection of the nail plate, lunula, and proximal, distal, and lateral nail folds is essential. The clinician should make note of any periungual scale, erythema, or other cutaneous findings that might indicate an underlying primary dermatologic disorder. The presence of increased longitudinal or transverse nail curvature and onycholysis should be assessed. Nailfold capillaroscopy should be performed to look for irregularities in the capillaries of the proximal nail folds, which may indicate an autoimmune connective-tissue disorder. Signs of cyanosis or ischemia suggest that circulatory insufficiency may play a role in the nail abnormalities.

Depending on the clinical severity and pertinent positives on ROS, it may be important to collect bloodwork to investigate further. In a brittle nail workup, physicians may be inclined to order thyroid studies, an erythrocyte sedimentation rate (marker of acute inflammation), complete blood cell counts, a comprehensive metabolic panel (which includes glucose, electrolytes, and markers of renal and hepatic function), antinuclear antibody titers, and iron (iron deficiency), ferritin, and zinc levels. If onychomycosis is suspected, nail plate and subungual debris samples should be sent for fungal culture, periodic acid-Schiff staining, and/or molecular testing.

The histopathology for onychorrhexis can be variable depending on the underlying cause. Nail plate thinning seen in onychorrhexis is caused by a shortening of the nail matrix length. However, a biopsy is not always performed, as onychorrhexis is more often a clinical diagnosis. When onychorrhexis is associated with a dermatologic disorder, biopsy of the nail matrix reveals typical histology for that disorder (eg, lichen planus, sarcoidosis, amyloidosis). In one study,[23] nail bed biopsy of age-related onychorrhexis revealed lichen planus–like changes including hyperkeratosis, hypergranulosis, and hydropic degeneration of the basal cell layer with necrotic keratinocytes. Epidermal thickening, papillomatous change, and bending of rete ridges was also noted.

It is important to exclude the possibility of damage to the nail matrix from long-term arsenic exposure, disorders of the microcirculation (ie, arteriosclerosis, Raynaud disease), and disorders of oxygenation (ie, anemia, polycythemia vera, sarcoidosis).[1] It is also vital to rule out systemic diseases, exogenous insults, and primary inflammatory dermatologic conditions impacting the nail matrix.[1]

Biotin

Biotin is a water-soluble B vitamin commonly found in egg yolk, cereal, peanuts, walnuts, and milk and may be used to treat symptoms of brittle nail syndrome.[24] The majority of studies investigating the impact of biotin on brittle nails have been small and patients were successfully treated with a dose of 2.5 mg/day.[25, 26, 27] Doses ranging from 2.5-10 mg/day have been suggested to be effective. Additional studies with larger sample sizes are needed to elucidate the magnitude of its efficacy. Of importance, oral biotin supplementation has been implicated in interference with blood testing, including tests measuring levels of troponin, thyroid function, and prolactin.[28] It may also impact pregnancy testing.[29] Therefore, it is important that patients disclose to their healthcare providers whether they are on biotin supplementation in order to ensure the most optimal clinical care. Patients taking typical-dose biotin supplements should withhold their dose at least 8 hours prior to any laboratory tests.

Hydroxypropyl chitosan

In patients with brittle nail syndrome, hydroxypropyl chitosan–based nail lacquer has been associated with a clinically relevant improvement of nail appearance. In one study, the use of oral biotin in addition to the nail lacquer prompted a synergistic effect associated with even further clinical improvement.[30, 31]

Poly-ureaurethane

Poly-ureaurethane is a polymeric hydrophobic solution that can be applied to the nail plate, which coats it and traps in moisture. Indicated for nail dystrophy, nail splitting, and fragility, it has also been suggested to improve the clinical appearance of nails affected by onychorrhexis.[7, 32]

Commercially available nail hardeners

Over-the-counter nail hardeners can be beneficial for strengthening nails but may also paradoxically contribute to worsening brittleness.[33] The formaldehyde in nail hardeners is considered the damaging agent in the paradoxical worsening, and it has also been linked to risk of allergic contact dermatitis and onycholysis in patients.[34, 35]

Nail moisturizers

Nail moisturizers in combination with lukewarm water soaks lasting 10-20 minutes can increase hydration in the nail plate and improve the appearance of nail fragility. Examples of nail moisturizers are petroleum jelly, lactic acid lotion, mineral oil, and urea cream.[2] In severe cases, patients may consider using these moisturizers under occlusion covered by cotton gloves.[2, 36]

To prevent brittle nails, it is helpful to follow a diet that is well-balanced in vitamins and minerals that are beneficial for the nails and skin. Direct trauma to the nails should be avoided. Patients should be advised to wear cotton gloves whenever involved in intensive manual work. It is recommended that patients take caution with the overuse of nail polish remover, as it can be drying to the nails. Other options for prevention include keeping nails short to reduce the surface area accessible for weakening and avoiding vigorous or frequent manicures and long-term, repetitive use of artificial nails.

Nail disorders can be difficult to treat and require time to see promising results. Successful resolution of brittle nails may even require multiple treatment strategies.[7] It is important that healthcare providers and patients collaborate to establish an optimal management plan.

Medical therapy should be strongly considered when brittle nail syndrome is suspected to have developed secondary to an underlying systemic or dermatologic disease. Otherwise, the level of medical therapy is guided by the desires of the patient and impact on quality of life.

Class Summary

Biotin supplementation may help to treat brittle nails.

Biotin (Appearex, Coenzyme R, Nail-ex)

Biotin may promote nail growth by aiding in the metabolism of amino acids responsible for building proteins associated with nail growth. It is known to function as a coenzyme of metabolic processes.

Poly-ureaurethane (Nuvail)

Poly-ureaurethane is a biocompatible, polymeric solution that forms a uniform film when applied to the nail; it adheres to the nail surface, preventing direct abrasion and friction on the nail surface; it also provides protection against moisture.