NAILS welcomes Paul Kechijian, M.D., as the new Nail Doctor. Dr. Kechijian, who practices in upstate New York, is chief of the nail section at New York University Medical Center. Kechijian has written numerous articles and done many presentations on nail diseases and disorders. He is currently writing a chapter on nails for a medical textbook.
Besides their ornamental role, nails serve several important, less appreciated, functions. They act as weapons of offense or defense, enable you to scratch that troublesome itch, protect the fingertip from injury (imagine slamming the car door on your finger without having a fingernail to protect it), enhance fingertip sensitivity (you can discern whether you have two or three pages between your fingers), and facilitate find tactile movement such as picking up tiny objects like pins or buttoning a shirt or blouse
The nail is formed by the matrix a boomerang-shaped structure located under the sin of the proximal nail fold and cuticle. The lunula, the white half-moon between the cuticle and nail bed is the only visible portion of the nail bed. The remainder of the matrix is concealed under the nail fold but it is continuously manufacturing new nail plate, day in and day out.
For practical purposes, the matrix can be divided in two: the near proximal) portion and the far distal portion. The proximal portion of the matrix manufactures the upper half of the nail plate while the distal portion including the lunula manufactures the lower half.
Nails grow continuously approximately 0.1 mm per day or 3 mm per month. The rate of nail growth is affected by a number of activities and environmental conditions. For example, during the day and in the summer, nails grow faster than at night or in winter. Nails grow more rapidly on longer fingers and on the dominant hand. Fever and serious illness slow the growth rate, while pregnancy enhances it. Minor trauma such as nail biting also stimulates nail growth, while in mobilization and poor nutrition slow it. Nails grow more rapidly in men and younger people than in women and the elderly. Toenails grow at one-half to one-third the rate of fingernails.
Why do nails grow at different rates? Just as the skin is stimulated by friction to produce a callus, injury to the nail can provoke “healing” by stimulating the matrix to regenerate the nail at a faster rate. During the day, the hand is more active, which means increased blood circulation. At the same time, nails and fingers are subject to repeated mild trauma and the nails grow faster.
Accordingly, since the dominant hand is more active, the nails on it grow faster. Longer fingers are subject to more trauma in proportion to their length; accordingly, those nails grow faster as well. In summer, because we tend to be more active, our circulation is better, we’re warmer, and our nails grow faster. And toenails grow more slowly than fingernails because toes are not as mobile as fingers and circulation in the feet is less efficient than in the hands.
Why men’s nails grow faster than women’s is open to speculation, but I believe that it’s because, in general, men are physically bigger and stronger than women. Pregnant women, however, have an elevated metabolic rate, which means everything in the body runs at a more rapid rate. Age is a factor because general body metabolism, circulation, activity, and health are generally at their highest level in younger persons. As things slow down with age, one would expect the nail matrix to slow down as well, making nails grow more slowly.
The matrix is a rapidly dividing tissue that is subject to the vagaries of health. With malnutrition, severe illness, or poor health, the matrix responds by cutting back on the rate of nail production, just as the body itself slows down.
In spite of all that’s beam written about growth enhancers, only the vitamin biotin has been shown to speed up nail growth. This single study also showed that biotin makes nails grow thicker and stronger as well. Other studies, however, have yet to confirm the effectiveness of this vitamin. I have not noted significant changes with biotin in the patients I have treated. Biotin is readily available in the vitamin section of most pharmacies. And, contrary to popular belief, neither gel nor calcium stimulates nail growth.
For reprint and licensing requests for this article, Click here.