Does your pre-approval letter say you can buy a house up to $180k or a loan up to $180k? If it is the later, then you can as long as you put $19k down.
Either way, talk to your lender. They are usually a little conservative just in case interest rates go up a little or you have a few last minute expenses. They may be able to get you in a little higher, especially if rates tick down a little.