This condition is brought on by a lack of vitamin D, which causes the body to be unable to absorb or deposit calcium. Less commonly, it can also be caused by a lack of calcium or phosphorus, but vitamin D deficiency is by far the most common cause.
8 ways to avoid paying an airline change fee. Everyone's been there: having to change a flight and facing a fee that's almost as much as the original airfare. (Change fees can be $200 on airlines like American, United and Delta, and international flight changes can cost up to $450). Most of us have resigned ourselves to paying the fee of changing our itinerary, no matter how far out the trip still is, but you shouldn't have to.
American Airlines. Passengers who make a same-day change to their flight are subject to a $75 change fee. Change fees for flights that result in a date change are subject to more expensive change fees; the exact price is determined by the airline based on the type of ticket the passenger purchased and what type of change is being made.