White spots on the nail is perhaps the most com­mon nail disorder. The disorder is called leukonychia, which literally means "white­ness of the nails." There are many types of nail whiteness, some of which indi­cate serious illness; happily, by far the most common cause of white spots on the nail is minor injury to the nail matrix.

These spots on the nail plate long have been referred to as liver spots, but they have nothing to do with the liver. They are caused by trauma or minor injury to the matrix. The spots grow out from the matrix with the nail plate and eventually dis­appear. Nail technicians should be aware that this type of leukonychia can he caused by over-vigorous push­ing hack of the cuticles with a metal or wooden instrument. Always soft­en the cuticles first with a lotion or warm water soak before pushing them back, and never use anything but gentle pressure.

A fungal infection of the nail may also cause a white nail plate. This is referred to as white superficial ony­chomycosis and will generally not dis­appear as the nail grows out unless it is treated with an antifungal medica­tion. White superficial onychomyco­sis most commonly appears on the toenails; the fingernails are almost never involved. A much rarer type of fungal infection that can cause white nails can affect both the fingernails and toenails. Additionally, the white­ness is in the nail plate and the nail bed. Although this type of fungal in­fection is rare, it is important not to disregard it because it may be a sign of AIDS or HIV infection. A derma­tologist can recognize, diagnose, and treat this disorder.

Exposure to some toxic materials — arsenic, for example — can cause horizontal white lines on the nail plate. Some chemotherapy patients also experience this disorder, known as Mee's lines. The lines will grow out with the nail and disappear when the chemotherapy is completed or the person is no longer being exposed to the toxic material.

Sometimes white nails are a symp­tom of a systemic disorder. For exam­ple, kidney disease can cause the half of the nail near the cuticle to be white, while the half near the free edge will appear pink. Called half-and-half nails or Lindsay's nails, the white is in the nail bed and not the nail plate.

When most or all of the nail bed is white, the condition is known as Terry's nails, which are most often as­sociated with liver disease. It should be made clear, however, that some­times Lindsay's nails and Terry's nails occur in healthy people. Only a doc­tor who performs the appropriate laboratory tests can determine if they are caused by an underlying illness.

Another example of white lines in the nail bed is called Muehreke's lines. These lines will appear when blood proteins such as albumin are extreme­ly low. This can occur in seriously ill patients or in people suffering from starvation. It also can occur when a person is taking cancer drugs.

Sometimes the nail may appear white when the nail plate separates from the nail bed, which is called onycholysis. This, however, is not a true white nail and is called appar­ent leukonychia. I will discuss ony­cholysis in another column.

In summary, white nails may or may not be an important sign of a medical disorder. Fortunately, in most cases white spots on the nail plate are caused by minor injury and should not be cause for concern. However, should the condition per­sist or its cause be inexplicable, rec­ommend the client have the disor­der evaluated by a dermatologist.

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