see also Nail Fungus
Fingernail (and toenails) are made up of karatin, a protein that is also part of hair and skin, that hardens to protect the finger tip and outer part of the toes. The nail grows as new cells are made in the matrix or the lunula (visible part of the matrix) which push the older cells forward compressing them into a healthy fingernail or toenail. The skin ridge covering the lunula is known as the cuticle and is composed of dead cells that forms a protective seal. The nail itself is known as the nail plate and the live tissue below it is known as the nail bed. The nail is always adding new cells and the rate of growth varies based on gender, season, location on the body, etc. The typical growth rate of fingernails is about ¼ inch every two months. Toenails grow much slower at a rate of ¼ inch every eight months.
Healthy nails appear even and smooth but irregularities can develop as a result of a variety of health conditions. Nails may be damaged due to accidents or the habit of biting or picking the nails. But other irregularities might be caused by a variety of health conditions. Listed below are some irregularities and health conditions based on a search of a variety of sources.
• Beau’s line (grooves across the nail) – aging, malnutrition, severe illness or surgery
• Bluish or purple nails – oxygen deprivation
• Brittle nails – aging, long-term exposure to moisture or nail polish
• Clubbing (nails soften, not firmly attached, increase angle at cuticle, curves down or convex and finger bulges) – diseases of heart and lungs
• Discolored and possibly painful area under the nail – bacterial infection
• Lifting of nail – some antibiotics
• Mees’ lines or Leukonychia (white lines or spots) – acute illness, heavy metal toxicity, chemotherapy
• Onychodystrophy (degenerate, pitted, splitting) – psoriasis
• Onychogryphosis (crooked and thickened) – bad fitting footwear, aging, trauma, psoriasis
• Onycholysis (brittle or splitting) – hyperthyroidism or hypothyroidism
• Onychomycosis (darken, discolor, thicken, disfigure, split) – fungal infection
• Red streaks in nail bed – infections elsewhere in the body (especially heart valve)
• Spoon nails or koilonychia (soft and look scooped out, concave) – iron deficiency, anemia, hemochromatosis, heart disease, hypothryroidism
• Other distortions – skin cancer, darkened cuticle a form of melanoma, dark streak down length of nail may be subungal melanoma
Many other colors and deformities are related to health concerns on many websites.
[search helps: eponychium, proximal fold, perionyx, margo liber, distal edge, hyponychium, quick, onychodermal band]