If you find your nail lifting off your finger like an airplane about to take off, you are probably experiencing onycholysis, a painless nail disorder that causes the nail to separate from the finger. As the nail disconnects, it turns yellow, white, or green and can be pried off if need be. It is best to just have the separated portion of the nail removed by a dermatologist.
Onycholysis can be caused by psoriasis and the UV light therapy some people use to treat it, bacteria and yeast infections, and allergic contact dermatitis from exposure to harsh chemicals. Onycholysis can also be an early sign of thyroid disease, particularly hyperthyroidism, where an overactive thyroid gland produces too much thyroid hormone.