My 7 year old

We recently went to the doctor after noticing early signs of puberty. The doctor rec. a bone density. They take an xray of her wrist and then a radiologist looks at the wrist bones which gradually develop after birth. They called today and said her bones are maturing too quickly and are referring us to a growth specialist/endocrinologist where they can assess it further.

I'm so confused.. she has always been tall for her age, 89 percentile. Is this as scary as it sounds? I don't even know where to begin researching or what questions to ask.

What do you think??