Located at the base of the fingernail just above the cuticle, a half moon, or to put it scientifically, a lunula is a whitish almost transparent shape that is part of the nail matrix. While spotting a half moon on a client’s nails is no cause for alarm, the discoloration or lack of one may warrant a call to their doctor.
According to an article from womansera.com, when the lunula is not visible on the nail it may indicate certain blood issues. In addition, the discoloration of the lunula (read: yellow, blue or red) may also be a sign of serious health concerns, including diabetes or heart problems.
A separate article from healthline.com states that if your client does not have a visible half moon on their nails, it could be a result of trauma or a sign of anemia, malnutrition or depression.
If you notice either a discolored lunula or one that is not visible on a client’s nails, suggest a call to their doctor to discuss if it is cause for concern.