White spots on nails can result from an injury or exposure to toxins. They may also indicate an underlying health condition, such as liver disease or anemia. Treatment can depend on the cause.
White spots can sometimes appear on the nail. When this happens, it is known as punctate leukonychia. There are several types of leukonychia.
Total leukonychia refers to a condition where the whole nail plate is totally white in color.
Another type is partial leukonychia. There are three main types of partial leukonychia:
- Punctate leukonychia, which presents as small white spots.
- Longitudinal leukonychia, which presents as a white band down the nail.
- Striate or transverse leukonychia, where one or more horizontal lines appear across the nail, parallel to the lunula. These are also sometimes called Mees lines.
Patches of white skin, known as leukoderma, underneath the nail can sometimes give the impression of partial leukonychia.
Leukonychia can be divided into two other types – true or apparent:
When the white spot or line is caused by damage to the nail, the condition is known as true leukonychia. With true leukonychia, the white areas remain unaffected when pressure is put on them. These areas will grow out as the nail does.
Apparent leukonychia occurs when the bed underneath the nail is affected. With apparent leukonychia, the nail bed affects the color of the nail plate. It will lessen or disappear under pressure and will not grow out with the nail.
Anyone can have white nails, no matter their sex, age, or ethnicity.
Leukonychia can be caused by a variety of different factors, depending on the type.
Injury to the nail plate or the area where the nail grows from, known as the matrix, can cause damage to the nail. This type of injury is common in children and is usually the cause of white spots on the nail.
The types of injury that can cause this include:
- nail biting
- day-to-day nail injuries
- footwear that is too small, causing abnormal pressure on the nails
As a result of these injuries, the spot will grow out with the nail.
Poisoning and drugs
Some forms of poisoning or medication can also cause leukonychia. This cause is relatively rare and often results in transverse leukonychia.
Poisoning and medication that can lead to white areas on or under the nails include:
- heavy metal poisoning from metals, such as lead and arsenic
- chemotherapy treatment for cancer, which is either given by mouth, injection, or infusion through the skin to try and kill cancer cells or stop them from dividing
- sulphonamides, a medication used for bacterial infections, such as skin infections, septicemia, and infections of the urinary tract