K.L.
Keep in mind that no matter what might be the cause for this, once it starts, there is not likely anything you can do to reverse it now. If your pediatrician suggests hormone therapy, you may want to conduct a thorough research on the subject before allowing it. I would talk to other doctors that were trained from other perspectives, such as a naturopath or a chiropractor, and I would talk with a pharmacist. There is nothing wrong with asking your pediatrician what he/she thinks and suggests. You can get much good information there, but I would not act on only what an MD recommends without doing more research. They know a lot, but their training is narrow and limited to mostly pharmaceutical approaches.
This happened to my niece. I suspected it may have been induced by medical interventions. Her mom was given a hormone by the doctor to bring on her delayed period when she was actually pregnant but the test did not indicate so. Also, my niece had been on anti-seizure meds for more than a year following a minor stroke from a broken blood vessel. The MDs mistook the stroke for a brain tumor and did brain surgery when she was 6. You may want to prepare your daughter for an early onset of her menses as well. My niece started hers before she was 9.
I have since learned that this is becoming more common so I would consider other things that all children are exposed to. I agree with what a nurse wrote to you. Feeding growth hormones to farm animals aught to be considered criminal. My son started to develop breasts at 13. I did some research and found that this is becoming increasing common due to the human growth hormone fed to farm animals. But it isn't just in the dairy products. It affects all meat and dairy that is not labeled organic or hormone free. I try to buy meat and dairy from farms that never feed animals such hormones or a daily diet of antibiotics. Farms are owned by big business now and the animals on those farms are kept caged and are crowded together in hideous conditions. The only way to keep disease down under those conditions is to feed them antibiotics on a daily basis.
After a few years of buying organic dairy and being much more careful about tainted meat products, our son's chest is back to normal. It helps that my husband hunts and we often have things like wild turkey, venison, and fish.
I spend more on groceries than I used to, but after seeing how those poor animals are farmed, it turns my stomach to support such things. Since mothers do most of the grocery shopping and we don't want our children poisoned, we really do have the power to entirely change this industry.
Children today are also exposed to far more vaccines than when I was a child. Some of the ingredients in these vaccines can induce hormonal changes. We do not have the studies we need to prove such things one way or another, but if more people looked at the list of ingredients in those shots and researched the toxic effects they have on developing bodies, I'm sure we would insist on better studies.
So, the only recommendation I have is to be vigilant about toxic exposures. Since your daughter is using deodorant, I would suggest making it a natural deodorant and to not use an antiperspirant. Be grateful that all you are seeing are signs of early physical development. So many children today are responding to their environment with extreme allergies, asthma, and neurological developmental delays.
Best of luck to you!