The fingernails can be a good indicator of potential anomalies in the body. Nail abnormalities, such as white spots or vertical and horizontal fingernail ridges, can be indicators of mineral deficiencies, circulatory problems, or even underlying diseases. The fingernails are similar to the trunk of a tree in that they can document occurrences in the lifespan of the nail.
The most common form of fingernail ridges are vertical ridges; these ridges run from the base of the nail plate to the tip and are generally parallel. Due to the fingernail anatomy, these ridges are formed by the nail plate moving forward on the nail bed. Moisture and oil levels present in the nail plate and bed can reduce with age, which in turn, leads to an increased prominence of vertical ridges. The use of chemical cleaning products can also increase their prominence as these products reduce oil levels in the nail plate. These ridges are not usually a sign of poor health or underlying disease, and they can be reduced through the application of vitamin E oil to the cuticle and nail plate.
Horizontal fingernail ridges can indicate underlying health issues but may also be caused by trauma. Some horizontal ridges can be caused through interruptions to the nail plate growth following dietary change, from physical trauma — such as impact trauma or other nail bed injuries — or severe emotional stress. They are known as Beau’s lines. These depressions in the nail plate can also be caused during illness and may disappear following a recovery period.
Other kinds of nail abnormalities are Muehrcke’s lines and Mee’s lines. Muehrcke’s lines are parallel pairs of white, indented lines that run transversely across the nail. They do not follow the path of the nail growth and do not move toward the tip of the nail over time. Muehrcke’s lines can indicate kidney disease, liver disease, and forms of malnutrition. Mee’s lines are a rare form of fingernail ridge and are normally an indicator of arsenic poisoning; unlike Muehrcke’s lines, Mee’s lines travel along the nail bed as the nail plate grows. Medical consultation is recommended following the development of any kind of horizontal nail ridges, as they are a key indicator of underlying health issues.