the streaks resolve spontaneously. There is a similar condition called Muehrcke's lines (apparent leukonychia) which differs from leukonychia in that the lines fade with digital compression and do not migrate with the growth of the nail. Leukonychia punctata Also known as "true" leukonychia, this is the most common form of leukonychia, in which small white spots appear on the nails. Picking and biting of the nails are a prominent cause in young children and nail biters. Besides parakeratosis, air that is trapped between the cells may also cause this appearance. It is also caused by trauma. In most cases, when white spots appear on a single or a couple of fingernails or toenails, the most common cause is injury to the base (matrix) of the nail. When this is the case, white spots disappear after around eight months, which is the amount of time the nails take to regrow completely. The pattern and number of spots may change as the nail grows. Longitudinal leukonychia Longitudinal leukonychia is far less common and features smaller 1mm white longitudinal lines visible under the nail plate and perpendicular to the nail bed. It may be associated with Darier's disease. Cause It is harmless and most commonly caused by minor injuries, such as nail biting, which occur while the nail is growing. Leukonychia occurs most commonly in healthy individuals, and is unrelated to any known nutritional or physiological deficiency. When caused by injury the marks will disappear as the nail grows outwards. While there are various sources that link dietary needs or vitamin deficiency with recurrent leukonychia, this notion has been challenged by some medical researchers. Other possible reasons for this problem can be linked to: Arsenic poisoning Lead poisoning Pneumonia Heart disease Kidney failure Ill health Hypoalbuminemia Vitamin deficiency Ulcerative colitis Liver cirrhosis Psychogenic stresses Onychophagia Trauma injury Occupational trauma Zinc deficiency Protein deficiency Psoriasis Eczema Iron deficiency Diagnosis A doctor will take a thorough medical history, and may take blood tests as well as examining liver and kidney function. Intracellular (red blood cell) assays are more sensitive than tests for plasma levels. Treatment Improvements have been reported from treating malnutrition associated with zinc deficiency and other minerals. References External links Conditions of the skin appendages