I do agree that most of the time the fewer people that know is better in the long run. I work in the medical field, I did end up talking to my manager/assistant manager about my diagnosis of PMDD. I decided to tell them when I knew it started to interfere with my job, like I was calling in more frequently. At first, because we were (and still are) short staffed my manager was not as understanding about it, but because my doctor filled out the medical leave papers and HR approved them, they couldn't do anything about it. (I found out another co-worker also got the cold shoulder when she had to take a medical leave as well.) As for my co-workers, I gave people very vague ideas of what was going on...."Oh I was having really painful periods....and had to get some tests done." I didn't feel comfortable telling my co-workers or even the co-workers I talk to outside of work; I wasn't sure if people would understand.