White nail

What is a white nail?

Nails are generally a pinkish colour. A white nail describes the appearance of one or more fingernails and/or toenails that are partially or completely white in colour. This appearance is also called leukonychia.

Classification of white nail

Total leukonychia is a whitening of the entire nail plate.

• Terry nails are white with reddened or dark tips.

Partial leukonychia has 3 subtypes:

• Punctate leukonychia:  small white spots
• Longitudinal leukonychia: lengthwise band of white nail
• Striate or transverse leukonychia: one or more white horizontal bands across the entire nail in parallel with the lunula, and are also called Mees' lines.

Muehrcke lines are a form of transverse apparent leukonychia due to variable blood flow under the nail; pressure on the nail plate makes them disappear. Vitiligo or leukoderma (white skin) can also cause apparent partial or longitudinal leukonychia.

Striate leukonychia due to chemotherapy

Punctate leukonychia of unknown cause

Apparent leukonychia due to vitiligo

Who gets a white nail?

White nails can affect anyone: males and females of any age or ethnicity.

What causes a white nail?

Trauma

The nail plate can be damaged in part or whole by injury to the nail plate or the matrix (growth area at the base of the nail). Disruption of the horizontal layers of keratin, with air trapping, results in reflection and lack of transparency.

Types of injury causing punctate leukonychia include nail biting, manicuring, knocks and bangs, and tight footwear. The white spots grow out as the nail grows (about 6 to 9 months for a fingernail). Striate leukonychia may follow damage to the nail matrix, and furrows and ridges may also appear in the. Total leukonychia can be follow a more serious injury, often with detachment of the nail plate from the nail bed, and alteration to the nail contour. 

Poisoning and drugs

White nails can be due to:

• Heavy metal poisoning (eg lead, arsenic)
• Chemotherapy
• Sulphonamides.

Inherited disorders

• Longitudinal leukonychia is sometimes associated with Darier disease, which can also cause erythronychia (a red band).
• Total leukonychia also sometimes runs in families.
• Striate leukonychia can be due to inherited conditions affecting keratinisation.

Systemic illness

Terry nails have been associated with:

• Liver cirrhosis 
• Chronic kidney disease
• Heart failure
• Protein malabsorption, eg in colitis
• Protein-losing enteropathy
• Diabetes
• Iron deficiency anaemia
• Zinc deficiency
• Hyperthyroidism

Infection

Superficial white onychomycosis is an irregular type of partial leukonychia due to chronic fungal infection due to the dermatophyte, Trichophyton interdigitale.

Skin disease

Leukonychia can be due to an inflammatory skin disease affecting the nail matrix, most often nail psoriasis or hand eczema.   

Differential diagnosis

Leukonychia should be distinguished from onycholysis, in which the nail plate appears white or yellowish because it has been lifted away from its underlying nail bed.

Investigations

If the cause of leukonychia is not clear, the following tests may be helpful.

• Nail clippings for mycology
• Nail biopsy
• Blood tests to evaluate systemic disease, especially low albumin levels

What is the treatment for a white nail?

Treatment depends on the underlying cause of leukonychia.

What is the outcome for a white nail?

Leukonychia due to minor trauma or medication may completely resolve over a few months, In other cases, the white nail plate remains long term, or become recurrent.