There seems to be a wide range of the amount of information different bosses want you to give. My previous boss said she didn't want details, just tell her that you were ill. Then she would try to guess why you were ill, by what was "going around". The day after I was ill and was back at work, everything on my desk was moved around, filed, thrown out, etc. When I asked where some of the items I had been working on were, I was told that because I was so sick the day before they had disinfected my desk/everything I had touched. Wow that was really nice of them, but I really don't think they were going to catch my migraine/menstral cramps. It took two days to find most of the stuff I was working on....
Now I tend to say something like "Migraine is so bad, I won't be in" or "Stomach bug that I don't want anyone else to catch". not TMI, but enough to know if it's contagious or just a personal demon.
As for your question, OP, I'd go with "hey, co-worker, I hope you are feeling better! you are? good! your description sounded like it was pretty rough! When I get the voicemails in the mornings, I give the messages to Big Boss. He/She never hears the details, so you can just say you are taking a sick day. If he/she needs more info, I'm sure they will contact you! Glad you are back!" just said with a conversation-like tone.