Nail Disorders — Approach

This page holds the general nail-complaint differential plus the nail findings not covered elsewhere; condition-specific detail is on the relevant standalone pages, cross-referenced below.

Nails grow slowly and respond slowly to treatment — average growth is about 1.62mm/month for toenails versus 3.47mm/month for fingernails, and the growth rate slows further with age, so assessing whether a nail treatment has worked takes months, and compliance over that time is often suboptimal.

Onycholysis

Separation of the nail plate from the underlying nail bed — a sign rather than a disease. Most commonly caused by psoriasis or trauma. The separation creates a subungual space with an air interface that gathers debris (dirt, keratin); usually seen in fingernails, but can develop in toenails from rubbing against shoes. Adverse local reactions to formaldehyde and resins in nail polishes/glues can also distort nails, as can self-induced trauma from obsessive cleaning/manicuring.

The band of discolouration at the end of a separated nail is usually in a straight line, compared with psoriasis or tinea; tinea can be distinguished by white or yellow streaks/spears” travelling proximally in the nail. “Greenish discolouration indicates invasion by Pseudomonas pyocyanea or Aspergillus. Green nail pigment is suggestive of Pseudomonas or Klebsiella colonisation, usually resulting from onycholysis, which creates a potential space for retained moisture and subsequent colonisation.

Management: first exclude psoriasis, tinea (check toe webbing), and trauma (check history).

• Fingernails — keep nails as short as possible; avoid inserting sharp objects under nails for cleaning; apply tape (e.g. Micropore) over the free edge for months until healed; avoid unnecessary soaps/detergents (wear gloves for housework/gardening); keep hands out of water; use a mild soap and shampoo. Nightly soaking in solutions of one part vinegar to three parts water for 15 minutes as needed can resolve and prevent recurrence of the green Pseudomonas/Klebsiella discolouration described above.
• Toenails — exclude fungal infection (clinical tinea pedis, culture); improve footwear to avoid rubbing.
• Pharmaceutical — daily imidazole (e.g. clotrimazole) or terbinafine; potent topical corticosteroids in lotion form may help; for Pseudomonas infection, soak in vinegar or Milton’s solution and/or gentamicin sulphate cream; if Candida albicans is confirmed, oral treatment (fluconazole or itraconazole) is best.

Refer difficult and unresponsive cases to a dermatologist.

Twenty-nail dystrophy (trachyonychia)

An uncommon disorder seen in preschool or pre-adolescent children, with thinning and roughening of all or almost all 20 nails. Trachyonychia — also called “rough nails” or “sandpaper nails” — can affect any number of nails; twenty-nail dystrophy specifically refers to trachyonychia affecting all twenty. It can occur at any age but is predominantly seen in children and young adults, with peak incidence between 3 and 12 years, and no significant difference between males and females. Rare familial (autosomal-dominant) cases are described.

It is classified into two subtypes: opaque trachyonychia — the more severe and more common form, with persistent, diffuse nail-matrix inflammation producing a thin, brittle, “sandpaper-like” nail with prominent longitudinal ridging and frequent onychoschizia (nail splitting) — and shiny trachyonychia, a milder, intermittent form where the nail plate keeps its lustre but develops numerous small geometric pits. Both subtypes can show koilonychia (spoon-shaped nails), and fingernails are more often affected than toenails.

May be a prodrome to psoriasis, lichen planus, or alopecia areata, but tends to be self-limiting — most cases resolve over 2–3 years. It can also be idiopathic, or associated with ichthyosis vulgaris, atopic dermatitis, or vitiligo. Diagnosis is primarily clinical; dermoscopy, nail clippings (to exclude fungal infection), and — occasionally — nail unit biopsy can help when the picture is unclear.

Treatment: often not needed, since trachyonychia can improve or resolve spontaneously — observation, reassurance, and emollients (opaque type) or camouflage nail polish (shiny type) are reasonable first steps. Reported to respond well to the very potent topical steroid clobetasol. Other topical options tried include calcipotriol/betamethasone dipropionate, keratolytics (urea cream), and intralesional triamcinolone. Systemic therapy (oral retinoids, biotin, ciclosporin, or JAK inhibitors) is rarely justified, since for most patients this is a cosmetic concern only.

Brittle nails

Nails break easily, usually at the distal end. Age-related, usually caused by local physical factors — repeated water immersion, exposure to chemicals (detergents, alkalis, nail polish removers) — and also by hypothyroidism and digital ischaemia. Systemic deficiencies (iron, vitamins) are not considered a common factor; calcium does not contribute to nail hardness and calcium deficiency does not cause brittle nails. No cosmetic applications appear to be helpful.

Management: avoid excessive hydration and trauma; wear rubber gloves with cotton liners for wet work; massage Vaseline or nail creams (e.g. Eulactol, NeoStrata) into the nail several times daily; nail polishes and hardeners (preferably without formalin) may give a good cosmetic result.