TODAY | November 22, 2012
>>> you to a young woman whose music video has been viewed nearly 2 million times online . but 10-year-old reagan smith is much more than a rising star . diana alviar will tell us reagan is also a survivor.
>> reporter: when reagan smith sings -- i wanna no when
>> reporter: the questions come from the heart.
>> like how long i'd have this disease because i still have it. i'm just in like temporary remission.
>> reporter: in first grade, reagan began to bruise and cuts refused to heal. tests raised more questions.
>> i can remember sitting in the car in the driveway and said how much do you know about blood diseases? she had an autoimmune disorder , her body was attacking her platelets.
>> you need your platelets to protect you against bleeding. you'll bump yourself, you'll bruise.
>> reagan 's case was worse than most. medicine and chemotherapy didn't work, so doctors decided to take out her spleen. having itp meant having to give up the things she loved most, riding horses, playing volleyball, even jumping on the trampoline in her own backyard.
>> i kind of felt like, you know, known as the sick kid. but her parents were determined not to let her illness define her.
>> so we said no victims here. you do your work.
>> reporter: reagan got to work organizing a blanket drive for kids in her hospital. and she channeled her energy into a safe indoor activity, music. it turned out she had serious talent.
>> reporter: the little girl 's big solo at a school mass blew everyone away. and then came an audition, the producer behind one of the biggest viral videos of all times, rebecca black "friday."
>> i went to try out and i saw there were like 20-year-old kids with guitars and ukuleles and things and i'm like, okay, this was just for fun and obviously not going to win.
>> i remember here because she was one of the youngest artists at the event. reagan sang better than 25-year-olds that performed. so we were all impressed.
>> impressed enough to write "i wanna know " specifically for reagan and shoot a music video featuring all of her favorite things.
>> after like two days, it had 40,000 views which was crazy.
>> reporter: much of reagan 's joy comes from knowing all of her profits will go to help kids like her. she's already raised $10,000 for the children's hospital.
>> it's amazing. it's very humbling when you're the mom and you've learned from your daughter. the fact that she truly always wanted to give back. she never sat and said, oh, poor me. not once.
>> reporter: a unique perspective.
>> i felt blessed i didn't get cancer and that i was lucky enough to be in remission. i mean, some people like are in tsunamis and tornadoes right now and their houses are destroyed.
>> reporter: a 10-year-old girl who has big plans for her future.
>> i really want to be a surgeon. i also want to sing on the weekends, kind of like a singing surgeon.
>> reporter: for "today," nbc news, palo alto , california.