White discoloration on the nails, medically known as leukonychia, occurs when there is a disruption in the keratinization process within the nail matrix. This appearance results from tiny air pockets trapped between the layers of the nail plate, which reflects light and causes the white color. Leukonychia is a broad term covering presentations ranging from small, harmless white spots to a complete whitening of the entire nail. While often the result of minor trauma, these changes can sometimes signal a more significant underlying health issue requiring medical attention.
Localized White Spots and Streaks
The most frequent cause of localized white spots, known as punctate leukonychia, is minor trauma to the nail matrix, the area at the base of the nail where growth originates. This type of injury is often forgotten, as the white spot may not appear for up to four weeks after the initial damage, such as a rough manicure or bumping a finger. Since the problem lies in the formation of the nail plate itself, these white spots are harmless and will naturally grow out with the nail over several months.
White discoloration can also manifest as streaks or patches on the surface of the nail plate due to external factors, a condition sometimes called pseudoleukonychia. A common cause is superficial white onychomycosis, a fungal infection that invades the top layer of the nail plate. This infection typically presents as soft, chalky white patches that can be scraped off the nail surface and is more common on toenails. Harsh chemicals, such as those found in strong nail polish removers, can also cause surface damage and lead to white, scaly spots.
Systemic Conditions Causing Nail Whiteness
When the entire nail turns white, it often signals a systemic condition rather than a local injury. True leukonychia totalis is the complete whitening of the entire nail plate, which may be inherited or acquired due to serious internal disease. This change results from a comprehensive defect in the nail matrix and is associated with conditions like chronic liver disease.
Certain patterns of whiteness are directly linked to underlying health issues, such as Terry’s nails, where the nail is mostly opaque white with only a narrow band of pink remaining at the tip. This distinctive appearance is a form of apparent leukonychia, meaning the discoloration is in the nail bed underneath the nail plate. It is frequently observed in patients with liver cirrhosis, congestive heart failure, or chronic kidney failure, and is thought to be caused by an overgrowth of connective tissue and changes in the blood vessels beneath the nail.
Another pattern, Muehrcke’s lines, presents as paired, horizontal white lines that run parallel to the nail base. These lines are also an apparent leukonychia, meaning they do not move as the nail grows, and they often signal low levels of protein in the blood, or hypoalbuminemia. This protein deficiency can stem from kidney disease, liver disease, or malnutrition, and the lines may disappear if the underlying albumin level is corrected. Transverse white lines that do move with nail growth, known as Mees’ lines, are a different marker, associated with a temporary disruption of the nail matrix often caused by severe systemic stress or exposure to toxins.
External and Nutritional Causes
White markings can also be caused by specific external exposures or deficiencies, though the common belief that white spots mean a calcium deficiency is incorrect. Nutritional deficiencies, particularly those involving zinc, iron, or protein, can sometimes manifest as white horizontal lines or spots on the nails. Since nails are composed primarily of the protein keratin, a lack of dietary protein can affect their strength and appearance.
Exposure to certain toxic substances or medications can also disrupt nail growth, leading to discoloration. Chemotherapy drugs, which interfere with cell division, are known to cause transverse white bands or lines on the nails. Similarly, exposure to heavy metals, such as arsenic, can result in the appearance of Mees’ lines across the nail plate, reflecting the period of toxic exposure.
When to Consult a Doctor
While most minor white spots are due to trauma and will resolve on their own, certain signs indicate the need for a professional medical evaluation. You should consult a doctor if the whiteness involves the entire nail or multiple nails symmetrically, as this pattern suggests a potential systemic cause. Any white discoloration that does not grow out with the nail or that involves distinct, parallel lines should also be investigated.
Immediate evaluation is necessary if the white nails are accompanied by other symptoms like persistent fatigue, sudden swelling, jaundice (yellowing of the skin or eyes), or shortness of breath. These accompanying signs could point toward liver, kidney, or heart conditions. If the whiteness is due to a fungal infection that is persistent, spreading, or causing the nail to become thick or crumbly, a dermatologist can provide appropriate antifungal treatment.