Onychorrhexis is the medical diagnosis for brittle fingernails that feature vertical ridges, and the primary cause is unusual dryness within the nail. Other causes include malnutrition, endocrine disorders, skin conditions such as psoriasis, low levels of thyroid hormone and Raynaud's phenomenon, though these are far less common.
People who suffer from onychorrhexis first notice that their nails peel easily at the tips and break easily. When they attempt to grow their nails out, they have difficulty getting them much past the fingertips.
To prevent onychorrhexis, keeping the hands from becoming too dry is the first step. Avoiding prolonged exposure to dry, cold conditions, as well as windburn or sunburn, is also important. People who wash their hands frequently often end up with dry skin, so adding a moisturizing lotion or soap is a helpful step. Avoiding unnecessary exposure to nail polish remover and similar chemicals helps as well.
Those who suffer from onychorrhexis because of skin conditions or endocrine disorders must take additional steps to moisturize their fingers and nails to reverse the condition. Those who are hypothyroid should ask their physician about thyroid replacement, which takes a number of different forms. Raynaud's phenomenon affects arteries in the legs and arms, and treatment protocols for Raynaud's, such as keeping the body warm and protecting the hands with rubber gloves while doing dishes, should clear up the brittle nails as soon as circulation is boosted once again.