(left) and
hangnail (top) Healthcare and pre-hospital-care providers (
EMTs or
paramedics) often use the fingernail beds as a cursory indicator of distal tissue
perfusion of individuals who may be
dehydrated or in
shock. However, this test is not considered reliable in adults. This is known as the
CRT or blanch test. The fingernail bed is briefly depressed to turn the nail-bed white. When the pressure is released, the normal pink colour should be restored within a second or two. Delayed return to pink color can be an indicator of certain shock states such as
hypovolemia. Nail growth record can show the history of recent health and physiological imbalances, and has been used as a
diagnostic tool since ancient times. Deep, horizontally transverse grooves known as "
Beau's lines" may form across the nails (horizontal, not along the nail from cuticle to tip). These lines are usually a natural consequence of aging, although they may result from disease.
Discoloration, thinning, thickening, brittleness, splitting, grooves,
Mees' lines,
small white spots, receded lunula,
clubbing (convex), flatness, and
spooning (concave) can indicate illness in other areas of the body,
nutrient deficiencies, drug reaction, poisoning, or merely local injury. Nails can also become thickened (
onychogryphosis), loosened (
onycholysis), infected with
fungus (
onychomycosis), or
degenerate (
onychodystrophy). A common nail disorder is an
ingrowing toenail (
onychocryptosis).
DNA profiling is a technique employed by
forensic scientists on hair, fingernails, toenails, etc.
Health and care The best way to care for nails is to trim them regularly.
Filing is also recommended, as to keep nails from becoming too rough and to remove any small bumps or ridges that may cause the nail to get tangled up in materials such as
cloth. Bluish or purple fingernail beds may be a symptom of peripheral
cyanosis, which indicates oxygen deprivation. Nails can dry out, just like
skin. They can also peel, break, and be
infected. Toe infections, for instance, can be caused or exacerbated by
dirty socks, specific types of aggressive
exercise (
long-distance running), tight
footwear, and walking unprotected in an unclean
environment. Common organisms causing nail infections include
yeasts and
molds (particularly
dermatophytes). Nail tools used by different people may transmit infections. Standard hygiene and sanitation procedures avoid transmission. In some cases, gel and cream cuticle removers can be used instead of cuticle scissors. Nail disease can be very subtle and should be evaluated by a
dermatologist with a focus in this particular area of medicine. However, most times it is a nail stylist who will note a subtle change in nail disease.
Inherited accessory nail of the fifth toe occurs where the toenail of the smallest toe is separated, forming a smaller "sixth toenail" in the outer corner of the nail. Like any other nail, it can be cut using a
nail clipper. Finger entrapment injuries are common in children and can include damage to the finger pulp and fingernail. These are usually treated by cleaning the area and applying a sterile dressing. Surgery may sometimes be required to repair the laceration or broken bones.
Effect of nutrition Biotin-rich foods and supplements may help strengthen brittle fingernails.
Vitamin A is an essential micronutrient for vision, reproduction, cell and tissue differentiation, and immune function.
Vitamin D and
calcium work together in cases of maintaining homeostasis, creating muscle contraction, transmission of nerve pulses, blood clotting, and membrane structure. A lack of vitamin A, vitamin D, or calcium can cause dryness and brittleness. Insufficient
vitamin B12 can lead to excessive dryness, darkened nails, and rounded or curved nail ends. Insufficient intake of both vitamin A and B results in fragile nails with horizontal and vertical ridges. Some over-the-counter vitamin supplements such as certain
multivitamins and
biotin may help in growth of strong nails, although this is quite subjective. Both vitamin B12 and folate play a role in red blood cell production and oxygen transportation to nail cells. Inadequacies can result in discoloration of the nails. Diminished dietary intake of omega-3 fatty acids may contribute to dry and brittle nails.
Protein is a building material for new nails; therefore, low dietary protein intake may cause anemia and the resultant reduced hemoglobin in the blood filling the capillaries of the nail bed reflects varying amounts of light incident on the nail matrix resulting in lighter shades of pink ultimately resulting in white nail beds when the hemoglobin is very low. When hemoglobin is close to 15 or 16 grams, most of the spectrum of light is absorbed and only the pink color is reflected back and the nails look pink.
Essential fatty acids play a large role in healthy skin as well as nails. Splitting and flaking of nails may be due to a lack of
linoleic acid. Iron-deficiency anemia can lead to a pale color along with a thin, brittle, ridged texture. Iron deficiency in general may cause the nails to become flat or concave, rather than convex. As oxygen is needed for healthy nails, an iron deficiency or anemia can lead to vertical ridges or concavity in the nails. RDAs for iron vary considerably depending on age and gender. The recommendation for men is 8 mg per day, while that of women aged 19–50 is 18 mg per day. After women hit age 50 or go through menopause, their iron needs drop to 8 mg daily. ==Society and culture==