Blood tests

My doctor has sent me for blood tests and an ultrasound scan (due in a week) as she suspects I have pcos. I had my bloods done yesterday which were testing for hormones mainly but other things also such as thyroid and diabetes. Only this morning the surgery rang me back to say the nurse wants me back in for more bloods on the liver in 2 weeks. What could this be testing for and why 2 weeks? I don't drink and I haven't taken any medication for months now.