You have to go to Relion's website to get the testing solution, that will tell you if it's accurate, or not. I don't know how to calibrate the meter, but at least you'll know if it's accurate, or not, once you get the testing solution.
It is free, but they do require you to give them all your contact info, including phone and email. Bad form on their part, but they don't carry it in Walmart stores, or online. You HAVE to go through the Relion Website to get it.
Mine didn't need calibration. I ordered the calibration fluid for free of the Relion website (I don't have the link, found it in another answer here) and it was reliable. I'd call Relion and they will send it to you. Sounds like your machine is off since it is so different from the lab results.