Short Answer: Yes you can (make sure to boil it and cool it first).
Long Answer: How low are you? If it is low enough that the alcohol content would be sufficient, I wouldn't do it and just take rigourous notes of what you did to miss the gravity so when you do another batch you can audit your process.
ALSO!!! Did you temperature adjust for your hydrometer reading? This is very important as if your wort is above the temp the hydrometer states on it, it will read low.
There are various online calculators for adjusting for temperature. I use Dave's Dreaded which seems to be pretty close.