White nails, medically termed leukonychia, refer to any discoloration of the nail plate resulting in a white appearance. This common finding ranges from small, harmless spots to complete whitening of the entire nail surface. The white appearance is caused by light scattering off abnormalities within the nail plate or changes to the vascularity of the nail bed beneath it. Understanding the pattern and location of this discoloration helps distinguish between a minor injury and a possible sign of an underlying health issue.
The Structure of the Nail and Its Normal Appearance
The appearance of a healthy nail is a translucent pink, derived from the dense network of blood vessels in the underlying nail bed. The nail plate is composed of transparent layers of keratinized cells produced by the nail matrix, the root located beneath the skin at the base. The matrix forms the cells that are pushed forward to create the visible nail plate.
The pale, crescent-shaped area at the base, known as the lunula, is the visible portion of the distal matrix. It appears white because the newly formed cells scatter light, partially obscuring the nail bed color. Any disruption to the matrix or the nail bed can change how light is reflected, resulting in a white appearance.
Temporary White Spots Caused by Physical Damage
The most frequent cause of white spots is minor trauma to the nail matrix, resulting in punctate leukonychia. These small, scattered white flecks are caused by microscopic damage to developing nail cells, which traps tiny pockets of air between the keratin layers, making the area appear white and opaque. Since the nail grows slowly, the injury may have occurred weeks earlier.
These spots start near the base and migrate toward the tip as the nail lengthens. They are harmless and resolve naturally once they are clipped off.
Transverse leukonychia is a different trauma-related pattern, appearing as one or more white horizontal lines spanning the width of the nail. This results from a single, more significant physical injury to the matrix. Like punctate spots, these lines are contained within the nail plate and will eventually grow out, indicating a temporary interruption of normal nail cell production.
White Nails as Indicators of Systemic Health Conditions
When most or all of the nail plate appears white, it may indicate an internal systemic condition rather than localized trauma. This generalized whitening is often categorized as “apparent leukonychia,” meaning the whiteness originates in the nail bed, not the nail plate, and the color disappears when pressure is applied. These patterns are typically bilateral, affecting multiple nails symmetrically.
Terry’s Nails
One distinct presentation is Terry’s nails, where the entire nail plate is opaque white with only a narrow, reddish-brown band remaining at the distal tip. This pattern is thought to be caused by increased connective tissue and reduced blood flow in the nail bed. Terry’s nails are associated with chronic health issues, including liver disease, congestive heart failure, and diabetes.
Half-and-Half Nails (Lindsay’s Nails)
Half-and-Half nails, also called Lindsay’s nails, feature a distinct demarcation across the nail. The proximal half is white, while the distal half maintains a normal pink, red, or brown color. This pattern is strongly associated with chronic kidney disease, particularly renal failure. The whiteness in both Terry’s and Lindsay’s nails does not move as the nail grows because the change is in the underlying tissue.
Total Leukonychia
Total leukonychia describes a condition where the entire nail plate is uniformly white, typically affecting all nails. While sometimes genetic, acquired total leukonychia can be linked to serious conditions, certain medications, or heavy metal poisoning.
Discoloration Patterns Caused by Infection and Specific Lines
White discoloration can also be caused by an external factor, such as a fungal infection, known as onychomycosis. Superficial white onychomycosis begins with white, chalky patches directly on the surface of the nail plate. This presentation often makes the nail surface rough, dry, and prone to crumbling. The infection starts on the outer layers and can sometimes be scraped off in the early stages, distinguishing it from changes deep within the nail. If left untreated, the fungus can spread and cover the entire nail, requiring specific antifungal treatment.
Another pattern is Muehrcke’s lines, which present as paired, narrow, white transverse bands running parallel across the nail bed. These lines are a type of apparent leukonychia, meaning they do not move forward with nail growth and fade temporarily when pressure is applied. Muehrcke’s lines are a sign of hypoalbuminemia, which is a low level of protein in the blood. This protein deficiency is often seen in cases of liver disease, malnutrition, or nephrotic syndrome, which causes protein loss through the kidneys.
When White Nails Require Medical Consultation
While most isolated white spots are benign and temporary, certain characteristics signal a need for professional medical evaluation. You should consult a healthcare provider if the whiteness affects multiple nails in a symmetrical pattern. Persistent discoloration that does not grow out with the nail warrants investigation. Also seek medical advice if the white nails are accompanied by changes in texture, such as thickening or crumbling, or by other general symptoms.