Formal:
* Espero que esteja bem. (This is the most direct translation and is suitable for formal situations.)
Informal:
* Espero que você esteja bem. (This is a more casual way of saying it.)
* Espero que esteja tudo bem. (This means "I hope everything is okay.")
* Tudo bem? (This is a very casual way of asking if someone is okay.)
* Está tudo bem? (This is a slightly more formal way of asking if someone is okay.)
You can also use phrases like:
* Espero que não tenha nada de mais. (I hope nothing serious happened.)
* Espero que esteja se sentindo melhor. (I hope you're feeling better.)
The best phrase to use will depend on your relationship with the person you are talking to and the context of the conversation.