hi jeane,
yes, i lost hair from my first surgery, but was VERY VERY sick going into it, and VERY sick for a while afterwards.
when you are sick, or having major surgery, or go through a big shock, your hair cycle reverses. that is to say, normally, 80% of your hair is in growth or "live" phase, whereas 20% is in shedding stage. In sickness/surgery, this process is reversed. So 80% is now shedding. this is almost always just a temporary response to the shock in your system. It is called
telogen effluvium.
I literally had some bald spots and went wig-shopping. A year later, a lot of my hair grew back, although not as thick/strong. 2-3 years later, my hair became healthier and the texture returned to normal.
of course, bloodwork and other things should be checked. it took me a long time, but my hair finally did grow back. sometimes vitamins/supplements and hair-strengthening products might help, but time was the best thing in my case. hope the same for you