Our nails are composed of nail halves, nail beds, and nail plates. Normal nail color should be smooth, shiny and transparent, while some of us often have white dots on the nails, longitudinal ridges and transverse grooves on the nails, rough and lusterless nails, some also have thickened and brittle nails, and even nail discoloration (white nails, black nails, blue nails, brown nails, etc.). Nail discoloration accounts for a high percentage of nail diseases. Nail color changes can be related to systemic diseases, skin diseases, systemic and local application of drugs, cosmetic products, etc. The following common nail discoloration possible causes to give you an introduction: 1, nail half-moon also known as arc shadow Because of its half-moon shape and named, light white, mainly seen in the thumb, especially the right thumb of people who are accustomed to use the right hand and the left thumb of left-handed people, other nail half-moon lighter, with age, nail half-moon also gradually become lighter (elderly people on the nail almost can not see the nail half-moon). If the nail half-moon appears red is seen in drug-induced lupus erythematosus, dermatomyositis, rheumatoid arthritis, congestive heart failure, carbon monoxide poisoning, liver cirrhosis, nail dystrophy, psoriasis (psoriasis), etc. Blue nail hallux is very rare and is generally associated with hepatomegaly, systemic medication, local exposure to mercury after sun exposure, and silver deposition. The nail hallux is brown and can be diffuse, appearing after topical fluorouracil, or punctate, as seen in familial congenital pigmented nevi. 2. The nail plate is normally pink due to the transparency of the nail plate The blood vessels under it reflect. The nail plate becomes white (white nail) is the most common nail discoloration. The white nail is diffuse and may be associated with systemic diseases (leprosy, cirrhosis, hypocalcemia, ulcerative colitis, etc.) or with occupational exposure to nitric acid, nitrite solutions and concentrated sodium chloride. Pitting white nail is the most common of the white nail, the incidence of the population can be as high as 62, mostly seen in the nails, these white spots due to improper nail trimming and cryotherapy or with psoriasis, typhus, measles, scarlet fever, syphilis, diabetes and heavy metal arsenic and lead poisoning can cause, of course, there are also fungal infections caused by nail fungus (gray nail) caused. Black nail plate (black nail) can be caused by malignant melanoma, acute trauma, local contamination by ink, contrast agent, silver nitrate, red wine, congenital melanocytic nevus, certain drugs, etc. Blue nail may appear due to silver deposition, severe hypoxia, exposure to certain agents, after taking chloroquine. Brown nail is caused with adrenocortical insufficiency, pituitary tumor, vitamin B12 deficiency, hyperthyroidism, malnutrition, syphilis, fungal infection, and local exposure to some agents. I believe that after reading the above introduction has a preliminary understanding of nail discoloration, our nails are closely related to health, once the nail discoloration should be promptly to the regular hospital to exclude some internal diseases, nail disease should not be ignored!