In the week between the Spirit of the New Workplace teaching weekends I am staying in my sister's house in the Santa Cruz mountains. My oldest niece, who works for a bank in Silicon Valley but lives with her school teacher husband in Orlando, called this morning and I answered the phone.
"Jan's Place."
"Joe, it's Sara."
"Sara! How are you?"
"I'm sick as a dog...and I have a question -- can you call in sick when you telecommute?"
Of course, you can call in sick regardless of whether you telecommute or not !. What matters is the fact whether you will be able to do your job well. If you are sick, you might not be able to do well on your job. Hence, you are better of calling in sick, taking the day off, resting and getting back to work refreshed and energised !
The ethical choice would be to call in sick, or in this case send an email to your boss saying you're sick and will be taking PTO.
There is an alternative solution, called comp time. IF you built up a bunch of hours off the books, and you're sick... then you could take comp time instead of PTO. some managers may allow a negative balance on comp time...I would imagine that this could also be negotiated.