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Nail plate continuously produced by the nail matrix at a rate of 2-3 mm/month for finger nails and 1-2 mm/month for toenails for the life of the person.
Nail growth varies with many factors including: age, gender, the finger or toe in question, as well as nutritional status.
The mean growth rate of toenails is 1 to 2 mm per month.
Typically fingernails grow at about 0.1mm/day and toenails at about 0.05mm/day.
The matrix lie under the proximal nail fold.
The nail plate emerges from the proximal nail fold.
The nail plate moves distally in relationship with the cuticle.
The nail plate adheres to the nail bed epithelium.
At the end of the digit the nail separates from the nail bed in the area of the hyponychium, where the distal aspect of the nail plate appears white.
Healthy nails are transparent and pink allowing the underlying vascular nail bed to be seen.
The proximal part of the nail covers the distal matrix, which is the whitish crescent the lunula.
Topical agents do not reach the nail matrix, which lies beneath the nail plate and proximal nail fold.
Removal of the nail plate may be necessary for diseases of the nail as drugs do not easily penetrate the nail plate.
Replacement of a fingernail takes approximately 6 months.
Replacement of a toenail takes approximately a year.
Beau’s lines are deep grooved lines that run from side to side on the fingernail or the toenail.
Muehrcke’s lines-smooth white bands that run parallel to the lunula across the width of the nail and which are not palpable: associated with metabolic stress including chemotherapy, infections and trauma which transiently impair protein synthesis.
Beau’s lines-indented lines across the nails seen with chemotherapy.
White nails, called Terry nails, with silver-white pallor of the proximal nail bed that may obscure the nail lunula in cirrhosis.
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Terry nails are involve mainly the thumb an index finger.
White stripes or spots are often the result of nail trauma.
Half-and-half nails are to be distinguished from Terry’s nails, in which the distal pink, red, or brown nail plate occupies less than 20% of the total length of the nail.
Half-and-half nails are characterized by a proximal white, ground-glass–looking nail plate and a distal pink, red, or brown nail plate, with the latter occupying at least 20% to 60% of the total length of the nail.
The proximal white band results from chronic anemia, increased thickness of the capillary wall, and overgrowth of connective tissue between the nail plate and the underlying structure with reduction of blood flow in the subpapillary plexus.
The distal pink, red, or brown nail plate is caused by increased melanin deposition, possibly stimulated by uremic or other toxins or by stagnant venous return.
Half-and-half nails occur in 8% to 50% of patients with chronic kidney failure, especially those on hemodialysis.
No correlation exists between the depth of the distal color band and the severity of kidney disease.
Half-and-half nails may also occur in association with Crohn disease, Kawasaki disease, Behçet disease, yellow nail syndrome, liver cirrhosis, type 2 diabetes mellitus, pellagra, citrullinemia, zinc deficiency, and use of medications, such as isoniazid, chemotherapy agents.
Yellow nail syndrome is characterized by yellow, dystrophic nails, lymphedema, and Sinopulmonary complications including pleural effusion, bronchiectasis and chronic sinusitis.
Fewer than 400 cases reported with estimated prevalence of 1/1,000,000.
Yellow nail syndrome usually occurs in adults older than 50 years without sexual predilection.
Yellow nail syndrome can be associated with cancer or autoimmune conditions or can be idiopathic.
Yellow nail syndrome may be linked to lymphatic abnormalities of protein leakage.
Yellow nail syndrome hypothesized to be related to structural or functional abnormalities in lymphatics resulting in oxidation of accumulated lipids, which leads to yellow discoloration of nails.
Yellow nail syndrome associated with slowing growth longitudinally of nails but nail thickness is doubled with an absent lunula and cuticle.
Half-and-half nails may also be idiopathic and in the healthy.
Onycholysis is common.
Yellow nail syndrome may be associated with pleural effusions that are exudative and serous, but can be milky or chylous.
Yellow nail syndrome may be a paraneoplastic process associated with lung, breast, gallbladder, and non-Hodgkin lymphoma.
Yellow nail syndrome management is symptomatic, however about 50% of patients undergo spontaneous resolution.
Vitamin E supplementation along with antifungal agents have shown some success in normalizing yellow nail discoloration.
Longitudinal half-and-half nails, a rare clinical variant, have also been described.13,17 The condition usually occurs on the thumbs and toes. Longitudinal half-and-half nails can be caused by chronic trauma to the digit or can be idiopathic.
Vertical nail ridges are associated with aging.
Splinter hemorrhages are associated classically with subacute bacterial endocarditis but can be seen with other embolic conditions such as the antiphospholipid syndrome, and the hypereosinophilic syndrome as well as nail trauma.
Fingernails grow an average of 3.5 millimeters (mm) per month.
Overall health, nutrition, and nail care can affect growth rates.
Stronger nails can grow longer because they are less likely to break or peel.
A healthy nail bed ensures the nail plate itself grows properly.
The hard part of the nail is called the nail plate, and is made primarily from a protein called keratin.
The nail bed is the living tissue underneath the nail.
If the nail breaks off below the fingertip, the nail bed can be exposed.
At the base of the nail is a structure called the nail matrix, which is where growth begins.
Long-term approaches to nail health support the body to keep the nail and surrounding skin healthy, enabling the nails to grow longer.
Nail painting does not affect growth.
Nails need a balanced diet to grow, including protein, water, fruits, vegetables, and a wide array of vitamins and minerals.
Patients who do not get enough iron may have brittle nails, or nails with dents.
Protein deficiency may cause ridges in the nails.
Diet changes can strengthen the nails and promote growth include:
Calcium, but few studies have definitively proven whether or not calcium improves nail health.
There is little evidence that biotin supplements help the nails grow faster.
Water can weaken the nails, making them soft and brittle.
The cuticles are thin pieces of skin that protect the nail matrix.
Cutting cuticles, which protect the nail matrix, cut very short can expose the nail matrix or nail bed, damaging the nails and causing infections.
Cuticles should be moisturized.
Aggressive manicure techniques, such as cutting the cuticles very short, can allow bacteria to enter the nail bed and weaken the nails.
Acetone polish remover can dry and weaken the nails.
The nails can provide an early warning sign to some health problems, such as nutritional deficiencies and diabetes.
Cutting toenails requires the ability to bend over, visual acuity and fine motor skills.
Community dwelling adults are found between 30 and 77% to have difficulty cutting their own toenails.
In patients 65 years and older almost 75% have a nail disorder.