Determining the cause of a change in nail color can be difficult, but knowing when the change occurred – while the nail plate was being formed or after it developed – is helpful. If the change in color occurred while the nail was being formed, the cause is internal; if it occurred after the nail was formed, the cause is external.
The shape of the bottom edge of the discoloration can tell you much about when the discoloration occurred. If the shape of the bottom edge parallels the shape of the lunula (the white semicircular area at the base of the nail near the cuticle) the cause is internal. If the bottom edge of the discoloration parallels the shape of the proximal nail fold, the cause is external.
The lunula is part of the matrix, which forms the nail plate. As the nail plate grows out from the proximal nail fold, the new growth retains the semicircular shape of the lunula. While this new growth is not visible in a normal nail, the new growth on a nail plate discolored by internal causes will be shaped in a half-moon like the lunula. Internal causes of nail discoloration include certain medications and illnesses.
If a nail becomes discolored after it is formed by the matrix, the discoloration will penetrate only the exposed surface of the nail plate, which means the color change will parallel the shape of the proximal nail fold. For example, a nail stained by nicotine or nail polish will often take on a yellowish tinge. As the nail grows out, the bottom edge of the stain will correspond to the shape of the cuticle.
At other times, the type of discoloration is of no help in determining its cause. For example, leukonychia (white nails) is not always the result of discoloration of the nail plate. True leukonychia is due to changes in the nail plate and can affect one or several nails. Alterations in the nail bed, which underlies and is completely separate from the nail plate, can produce a nail that appears white. This condition is called apparent leukonychia. Understanding the difference between the two types of leukonychia will help you determine the cause of a client’s white nails.
Apparent leukonychia is caused by anemia, kidney and liver disease, and certain medications. All the nails will be involved when there is an underlying disorder that is causing the nail beds to whiten.
True leukonychia is much more common than apparent leukonychia. True leukonychia is commonly denoted by a spattering of white spots on the nail; the entire nail is rarely involved. The white spot s is rarely involved. The white spots are most often caused by trauma to the nail or brief fluctuations in nail formation. Vitamin and protein deficiencies; arsenic poisoning; heart, kidney, and gastrointestinal disorders; internal malignancies; and dermatological disorders can also cause white spots to appear on the nails.
The extent of the white spots in true leukonychia is one helpful clue to their cause. When only a few nails are involved, the spots are likely caused by minor trauma or fluctuations in nail formation. If all or most of the fingernails are involved, the white spots are likely caused by an underlying disorder.
When you are attempting to distinguish whether a discoloration is caused by internal or external factors or if white nails are caused by changes in the nail plate or nail bed, look for clues by carefully inspecting the shape and extent of the discoloration. If the cause of the discoloration appears to be internal, refer the client to a dermatologist. If you are concerned about the condition of a client’s nails, don’t hesitate to refer her to a dermatologist. Most clients will appreciate your concern and take your recommendation seriously.