Does having a small half-moon or vertical lines on your nails mean that they are unhealthy? Wrong! These are the situations that really need your attention...

Some time ago, we discussed the problem of black lines suddenly growing on nails. After the article was published, readers raised more questions about nails, so we decided to continue the topic of nails.

What does the half-moon on the nails mean?

Many years ago, the saying "small or missing half-moon on nails = unhealthy" was circulated on the Internet, and it has been spreading to this day. Even though many professionals have debunked the rumor, there are still many friends who feel sorry for their fingers that have "insufficient half-moons".

Image source: Bing search screenshot

The reason why nails can grow continuously toward the fingertips is that there is an active area called "nail matrix" at the root of the nail that continuously produces fresh nail cells, which are transported to the fingertips like the waves of the Yangtze River. Most of the area of ​​the nail matrix is ​​covered by the skin, and a small part of the uncovered area is a white half-moon shape, which is the so-called crescent, scientifically known as "lunula".

So, what does it mean if there is no half-moon on the nail? Most of the time, it can only mean that the nail matrix is ​​completely covered by the skin. As long as the nail is still growing normally, the half-moon is objectively present. Even if you can't see it, it is still working hard and conscientiously.

Of course, the lunula can also be affected by changes in physical conditions. For example, connective tissue diseases (systemic lupus erythematosus, rheumatoid arthritis, etc.) and psoriasis sometimes cause the lunula to turn red. However, these diseases often have other more obvious symptoms, and we do not rely on the appearance of the lunula to diagnose them. For example, a person with joint pain, joint swelling, and joint stiffness does not need to wait until the lunula changes before suspecting that he has rheumatoid arthritis.

On the other hand, if you don’t feel any discomfort in your body and your nails are flat, smooth, white and translucent in a healthy state, you don’t need to worry about whether the lunula is healthy. Normal nails can indirectly prove its health.

What are the vertical lines on the nails?

Nails are the result of the concerted efforts of a group of cells in the nail matrix. Different cells have different working efficiencies, just like hairs are thicker and thinner, and nails cannot be completely the same thickness from left to right, so many people have physiological vertical lines on their nails. Physiological vertical lines will become more obvious with age, and trauma to the nail matrix, as well as some diseases such as lichen planus, rheumatoid arthritis, and peripheral vascular disease, will also aggravate the vertical lines on the nails.

Common nail abnormalities

Sometimes, some factors affect the proliferation of part or all of the nail matrix, resulting in slow growth of part or the entire nail, and various strange spots or lines. The following are some common nail abnormalities:

1 Transverse groove of nail (Beau's line)

Physical trauma (such as shoe compression), local inflammation (such as paronychia), some drugs (such as chemotherapy drugs), viral infections (such as hand, foot and mouth disease) and other factors can affect the normal proliferation of nail matrix [3-5]. After the influencing factors are removed, the growth of nails returns to normal. The nails produced during the affected period are sandwiched between the normal nails in front and behind, forming a horizontal groove running through the left and right sides, which is medically called "Beau's line".

Beau's lines. Image source: Reference [6]

2 Longitudinal grooves of the nails are manifested as splitting or depression of the midline of one or more nails (onychodystrophy). Physical trauma such as nail biting, manicure, and friction are common causes.

Malnutrition. Image source: Reference [6]

3 White Armor

It can be caused by trauma or by the presence of parakeratinized cells at the bottom of the nail plate, which will continue to move forward as the nail grows.

White nail. Image source: Reference [6]

4. Michaelis Line

Mie's lines are white stripes parallel to the nail base, and are related to abnormal keratinization of the nail matrix, so they also move forward as the nail grows. Mie's lines may mean more serious health problems. In addition to trauma, cancer, and the use of chemotherapy drugs, renal failure, heart failure, sickle cell disease, and exposure to heavy metals such as thallium and arsenic can also cause Mie's lines.

Michaelis lines. Image from Wikipedia

5. Thickening of nails

It is often caused by onychomycosis. In addition to thickening, the nails may also change color and become deformed.

Onychomycosis. Image source: Reference [6]

6 Spoon-shaped nails

The nail is concave in the middle and raised at the edges, shaped like a spoon. Spoon-shaped nails are often associated with iron deficiency anemia or other systemic diseases.

Spoon-shaped nail. Image source: Reference [6]

7 Splinter hemorrhage

Small longitudinal blood streaks appearing on the nail plate near the fingertips are caused by rupture of capillaries in the nail bed and are often caused by trauma. Psoriasis, endocarditis, kidney disease, and some systemic diseases can occasionally cause splinter hemorrhages.

Splinter hemorrhage. Image source: Reference [6]

8-point concave nail

Local trauma to the nail root sometimes leaves a small pit on the newly grown nail. Diseases such as psoriasis and eczema sometimes leave more pits.

Psoriasis nail concave spots. Image source: Reference [7]

In addition to pitting, psoriasis can also present with onycholysis and rough nails.

Psoriatic nail peeling. Image source: Reference [7]

Psoriatic nails. Image source: Reference [7]

Nails are just inconspicuous parts of the body, but they can also have various problems. When marketing accounts scare people, they only focus on the crescent, which is a bit wrong. However, the examples listed in this article are far from covering all nail abnormalities. If you find that your nails are growing abnormally, you should still actively seek help from a dermatologist.

References

[1]Tunc SE,Ertam I,Pirildar T,Turk T,Ozturk M,Doganavsargil E.Nail changes in connective tissue diseases:do nail changes provide clues for the diagnosis?.J Eur Acad Dermatol Venereol.2007;21(4):497-503.

[2]Sandre MK, Rohekar S, Guenther L.Psoriatic Nail Changes Are Associated With Clinical Outcomes in Psoriatic Arthritis.J Cutan Med Surg.2015;19(4):367-376.

[3]Bodman MA.Nail dystrophies.Clin Podiatr Med Sur.2004;21(4):663-687

[4]Piraccini BM, Alessandrini A. Drug-related nail disease. Clin Dermatol. 2013;31(5):618-626.

[5]Wei SH, Huang YP, Liu MC, et al. An outbreak of coxsackievirus A6 hand, foot, and mouth disease associated with onychomadesis in Taiwan, 2010. BMC Infect Dis. 2011;11:346. Published 2011 Dec 14.

[6] Tully AS, Trayes KP, Studdiford JS. Evaluation of nail abnormalities. Am Fam Physician. 2012;85(8):779-787.

[7] Canal-García E, Bosch-Amate X, Belinchón I, Puig L. Nail Psoriasis.

Author: Doctor Fei Dao Duan Yu

Review | Feng Jun, Deputy Chief Physician, Dermatology Department, General Hospital of Datong Coal Mine Group Co., Ltd.