What is shore nails, likely referring to brittle nail syndrome?

Shore Nails (Brittle Nail Syndrome)

Shore nails, more commonly known as brittle nail syndrome, is a condition characterized by nails that split, flake, crumble, become soft and lose elasticity, affecting up to 20% of the population, particularly women over 50 years of age. 1

Clinical Presentations

Brittle nails manifest in several distinct patterns:

• Onychoschizia: Lamellar splitting where the nail plate separates horizontally in layers 1, 2
• Onychorrhexis: Longitudinal ridging with splitting or brittleness of the nail plate, characterized by vertical furrows running from cuticle to nail tip 3, 2
• Superficial granulation of keratin: Surface roughness and fragility 1, 4
• Worn-down nails: Progressive thinning and weakness 1

The fingernails are more commonly affected than toenails, with roughness of the nail surface being a hallmark feature. 1, 4

Underlying Causes

Primary Form

Idiopathic brittle nail syndrome is the most common presentation, where no underlying cause can be identified despite thorough evaluation. 5, 1 This form results from abnormalities in keratin structure, keratin-associated proteins, water content, and/or lipid content of the nail plate. 4

Secondary Causes to Rule Out

Before diagnosing idiopathic brittle nails, exclude these conditions:

• Inflammatory dermatological conditions: Psoriasis causes nail involvement with pitting, onycholysis, and subungual hyperkeratosis; lichen planus affects approximately 10% of patients with nail thinning and subungual hyperkeratosis 6, 7
• Fungal infections: Present with thickening, discoloration, and friable texture—but the nail becomes soft and friable, unlike the hard brittleness of brittle nail syndrome 6, 8
• Systemic diseases: Hypochromic anemia, iron deficiency, peripheral vascular impairment, and endocrinopathies 2
• Medication-induced: Taxane chemotherapy (docetaxel, paclitaxel) causes nail matrix damage with brittle nails, ridging, and thinning 6
• Chronic paronychia: Infection and inflammation in the nail matrix area leads to proximal nail dystrophy with associated ridging, particularly in patients with chronic moisture exposure 3

Environmental Factors

Progressive dehydration of the nail plate from environmental and occupational exposures plays a critical role in nail brittleness. 5 Household daily chores, prolonged water exposure, and exposure to solvents or harsh chemicals are particularly damaging. 6, 2

Diagnostic Approach

Do not assume fungal infection without laboratory confirmation, as 50% of dystrophic nails are non-fungal despite similar clinical presentation. 8

Key diagnostic steps:

• Examine all 20 nail units for characteristic patterns of splitting and brittleness 9
• Perform direct microscopy with potassium hydroxide (KOH) preparation and fungal culture if fungal infection is suspected 8, 3
• Assess for inflammatory skin conditions (psoriatic plaques, lichen planus lesions) 7
• Review medication history, particularly chemotherapy agents 6
• Evaluate for systemic conditions including anemia and vascular insufficiency 2

Treatment Strategy

Preventive Measures (Essential First-Line)

Daily application of topical emollients to periungual folds, nail matrix, and nail plate, combined with protective nail lacquers to limit water loss, forms the foundation of management. 6, 3

Additional protective measures:

• Wear cotton gloves under plastic gloves when performing household chores or working with water/chemicals 6, 2
• Avoid damaging behaviors: manipulation of cuticles, nail biting, using fingernails as tools, prolonged water soaking, and artificial nails 6
• Keep nails trimmed short to minimize trauma 6

Pharmacological Treatment for Idiopathic Brittle Nails

Oral biotin (vitamin B7) supplementation is the most evidence-supported systemic treatment for idiopathic brittle nail syndrome. 5, 1

• Biotin supplementation has been reported useful in improving nail strength 5, 1
• Additional supplements include trace elements and amino acids, particularly cysteine 1
• Other vitamins may provide benefit in cases of nutritional deficiency 5

Topical Treatments

• Nail hardeners: Modified nail varnish base coats or dimethyl urea-based products (preferred over formaldehyde-containing products) 2
• Topical moisturizers and restructuring lacquers: Help reduce water loss and provide structural support 1

Treatment of Secondary Causes

When an underlying condition is identified, address it specifically:

• For psoriasis or lichen planus affecting <3 nails: Intralesional triamcinolone acetonide 5-10 mg/cc for nail matrix involvement; topical steroids with or without vitamin D analogs for nail bed involvement 3
• For confirmed fungal infection: Pulse itraconazole (5 mg/kg/day for 1 week every month) for 2 months (fingernails) or 3 months (toenails), or daily terbinafine for 6 weeks (fingernails) or 12 weeks (toenails) 8
• For medication-induced brittleness: Consider temporary dose adjustment in consultation with the prescribing physician 3

Common Pitfalls to Avoid

• Do not diagnose fungal infection based on appearance alone—laboratory confirmation is essential, as fungal infections cause soft, friable nails rather than hard, brittle splitting 6, 8
• Do not overlook environmental factors—progressive dehydration from occupational and household exposures is a major contributor that requires behavioral modification 5, 2
• Do not neglect patient education—strong patient cooperation is essential for treatment success, as management requires consistent protective measures and avoidance of damaging behaviors 6, 4