The half-moon at the base of your nails is called the lunula. As the article states, it is “the visible part of the nail matrix, where new nail cells are produced.” They are usually white or pale and most noticeable on the thumbs. Size and visibility vary among individuals and can change with age.

Lunulae are often harmless. Some people have small or hidden lunulae, which is usually normal. The article notes, “Small or absent lunulae…is often normal, especially if they’re hidden under the cuticle.”

Changes in lunula size can signal health issues. “Enlarged lunulae may be associated with thyroid dysfunction or circulation problems.”

The color of lunulae can also give clues: blue could suggest oxygen deficiency, red may link to heart problems, and yellow can indicate fungal infections or systemic issues.

The article warns, “If you notice significant changes in your lunulae…especially if accompanied by other symptoms like fatigue, dizziness, or weakness, it’s advisable to consult a healthcare provider.” Lunulae can offer insight, but they are just one part of overall health.