Can I Just Say I Don't Know?

Trainee pharmacist asked me to go through prescriptions with her, but it was on the topic of endocrinology and frankly speaking I'm really weak in this topic. My endocrine knowledge is just limited to diabetes and thyroid problems. Any other cheem topics such as adrenal gland problems really baffles me. Told her not to ask me endocrine problems cos I'm really not good in this topic so I can't teach much. Also warned her not to ask me about O&G cos I don't like that topic, but actually I can go through the O&G topic if she wants to cos I have been teaching O&G for 2 yrs. Just that I don't like the topic. *shrugs shoulders*

At times like these, I wonder if I can just say I don't know. There's no way for me to know everything so why should I have to pretend I know just because I'm the senior...