"leukonychia" is the medical term for white nails.
Extreme cases of leukonychia, in which the nails turn entirely white (leukonychia totalis) or develop white bands (striate leukonychia), can indicate anything from arsenic poisoning to leprosy. Leukonychia has also been linked to zinc deficiency, typhoid fever, frostbite, trichinosis, gout, diphtheria, cholera, acute rheumatism, myocardial infarction, colitis, malaria, Hodgkin's disease, sickle cell anemia, etc
Mere spots are extremely common and undoubtedly harmless. The white color has been variously attributed to trapped air and to defective keratinization, keratinization being the process by which nails are formed. The air bubbles and/or opaque, imperfectly keratinized granules within the nail cells refract light and the spot appears white.
The precise cause of leukonychia is a mystery. It's said to be more common in the young and in women, and often shows up when the body undergoes stress or trauma, such as a blow to the fingertips. Excessive manicuring can make things worse. Sometimes, it's helpful to take Zinc supplements...
Hope that helps!
The healthy nail plate is pink, and the nail looks white as it grows off the nail bed. Nails can be discoloured by various factors including:
* Nail polish
* Some medications, including antibiotics and anti-malarial drugs, and some of the drugs used in chemotherapy
* Nicotine from cigarette smoking
* Hair colouring agents.