According to Popular Science China, some time ago, we discussed the sudden growth of black lines on nails. After the article was published, readers and friends raised more doubts about nails, so we decided to continue to talk about nails.
What does the crescent moon on the nail say?
Many years ago, there was a saying on the Internet that "nail crescent is small or missing = unhealthy", and it has been poisoned to this day. Even if there are already many professionals who have done relevant refuting rumors, there are still many friends who look at the ten fingers of "insufficient crescent moon".
Image source: Bing search screenshot
The reason why the nail continues to grow energy to the fingertip is because there is an active area at the base of the nail called "nail matrix" that continuously produces fresh nail cells, which are transported to the fingertip like the Yangtze River pushing forward waves. Most of the area of the nail matrix is covered by the skin, and a small part of the uncovered area is white half-moon-shaped, which is the so-called crescent, the scientific name "nail half-moon".
So, what does the absence of a crescent on the nail say? Most of the time, it only means that the nail matrix is completely covered by the skin. As long as the nails are still growing normally, the crescent is objectively present. Even if you can't see it, it's still working hard and seriously.
Of course, the crescent moon can also be affected by changes in physical conditions, such as connective tissue disease (systemic lupus erythematosus, rheumatoid arthritis, etc.), psoriasis, and sometimes symptoms of reddening of the crescent. But these diseases tend to have other, more pronounced symptoms, and we don't rely on the appearance of the crescent to diagnose them. For example, a person with joint pain, joint swelling, and joint stiffness does not need to wait until the crescent changes to wonder if he has rheumatoid arthritis.
Conversely, if the body does not feel any discomfort, and the nails are also flat and smooth, white and translucent in a healthy state, there is no need to worry about whether the crescent moon is healthy, and normal nails have indirectly proved its health.
What is the vertical line of the nail?
Nails are the result of the joint efforts of a group of cells in the nail matrix. Different cells work differently, just like hair has thick and thin, nails can not be completely consistent from left to right thickness, so many people have physiological vertical lines on their nails. Physiological vertical lines will become obvious with age, trauma to the nail matrix, and some diseases such as lichen planus, rheumatoid arthritis, peripheral vascular disease, etc. will also aggravate the vertical lines of the nails.
Common nail abnormalities
Sometimes, factors can affect the proliferation of some or all of the nail matrix, resulting in local or entire nail growth retardation, resulting in various strange spots or lines. Here are some common nail abnormalities:
1
Koyokogou (Broaden's Line)
Physical trauma (eg, shoe crushing), local inflammation (eg, paronychia), some drugs (eg, chemotherapy drugs), viral infections (eg, hand, foot and mouth disease) can affect the normal proliferation of nail matrix [3-5]. After the influencing factors are removed, the growth of the nail returns to normal, and the nails produced during the affected period are sandwiched by the normal nails before and after the front, forming a transverse groove that runs through the left and right, medically known as the "Broads' line".
Bysseol's line. Image source: References [6]
2
Nail longitudinal sulcus
Manifested as splitting or depressed midline of one or more nails (nail dystrophy), physical trauma such as nail biting, manicure, and friction are common triggers.
Nail malnutrition. Image source: References [6]
3
White armor
It can be caused by trauma or by the presence of dyskeratotic cells at the bottom of the plate, which will continue to move forward as the nail grows.
White armor. Image source: References [6]
4
Mie line
Michael's line is a white stripe parallel to the methyl base, which is associated with abnormal keratinization of the nail matrix, so it also moves forward as the nail grows. Michael's thread can mean a more serious health problem, and in addition to conditions such as trauma, cancer, and the use of chemotherapy drugs, kidney failure, heart failure, sickle cell disease, and exposure to heavy metals such as thallium and arsenic can also produce Michael's line.
Mie line. Image from Wikipedia
5
Thickening of the nails
Often caused by onychomycosis, in addition to thickening, nails can also have discoloration, deformation and other characteristics.
Onychomycosis. Image source: References [6]
6
Spoon nail
The nails are sunken in the middle, with upturned edges, shaped like spoons. Spoon nails are often associated with iron deficiency anemia or other systemic natures.
Spoon nail. Image source: References [6]
7
Fissure hemorrhage
Small longitudinal streaks of blood near the fingertips of the nail plate are caused by rupture of the capillaries in the nail bed, often due to trauma, and occasionally schizoid hemorrhage from psoriasis, endocarditis, kidney disease, and some systemic diseases.
Fissure hemorrhage. Image source: References [6]
8
Dotted nails
After local trauma to the base of the nail, a small pit is sometimes left in the newly grown nail. Diseases such as psoriasis, eczema, etc. sometimes leave more pits.
Psoriasis spotted concave nails. Image source: References [7]
In addition to punctate depressions, psoriasis can also have nail peeling, rough nails and other manifestations.
Psoriasis nail peeling. Image source: References [7]
Psoriasis rough nails. Image source: References [7]
Nails are just small inconspicuous parts of the body, but they can also cause various problems. When the marketing number scares people, it only focuses on the crescent moon, which is somewhat of a misstep. However, the examples listed in this article are far from covering all nail abnormalities, and if you find that your nails are wrong, you should actively seek help from a dermatologist.
Resources
[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. doi:10.1111/j.1468-3083.2006.02012.x
[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. doi:10.1177/1203475415573663
[3] Bodman MA. Nail dystrophies. Clin podiatr med on. 2004; 21(4):663-687
[4] Piraccini BM, Alessandrini A. Drug-related nail disease. Clin Dermatol. 2013; 31(5):618-626. doi:10.1016/j.clindermatol.2013.06.013
[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. doi:10.1186/1471-2334-11-346
[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. Nail psoriasis. Proceedings Dermosifiliogr. 2022; 113(5):481-490. doi:10.1016/j.ad.2022.01.006