Apple is providing a powerful API allowing to search the iTunes store using various parameters.
The documentation is available here: http://www.apple.com/itunes/affiliates/resources/documentation/itunes-store-web-service-search-api.html
What can you do with this?
For example you can check your releases on the store using your artist name: https://itunes.apple.com/search?term=
(enter your artist name after term=)
Search the store by UPC: https://itunes.apple.com/lookup?upc=
(enter your UPC after upc=)
There are multiple search combinations, all are described in the documentation.