I'm sorry to hear that Sparks has high levels of the liver enzyme ALT and high bile acids.
I understand that this is puzzling for you because she seems so normal.
With these results I suspect that the tentative diagnoses is a liver shunt. Of course you are concerned as this can be a life threatening condition.
The good news is that it sounds like Sparks has grown at what seems to be a normal rate and is behaving like a normal puppy, so she must have some part of her liver that has been working. Puppies that are diagnosed very young and have symptoms of the shunt (poor growth, seizures, dull mentation, chronic diarrhea) tend to be the most severely affected and thus have the most guarded long term prognosis.
There are different types of shunts. There can be one abnormal vessel out side the liver that interferes with proper liver development as then the blood supply bypasses the liver. Or there can be several vessels causing most of the blood to bypass the liver in or outside of the liver. Or there can be multiple tiny blood vessels within the liver which are abnormal.
If the shunt is a single one out side of the liver and can be successfully occluded without raising blood pressure within the liver then surgery is the way to go.
If the shunt is involving multiple small vessels within the liver or if when the shunt is occluded blood pressure within the liver rises then medical/diet therapy is the way to go.
Is your pup of normal weight compared to litter mates?
The good news is that the fewer the symptoms that are present the better the patient tends to do in the long run.
Have abdominal radiographs or an ultrasound been done, and if so is her liver small?
If she has a small liver, and an elevated bile acids test then the next step would be imaging studies to identify what type of shunt is present and come up with a plan for treatment.
Really prognosis will depend upon whether they can successfully tie off her shunt.
If so prognosis is very good.
If not then even if they can partially tie it off that will help.
Otherwise medical therapy/diet is the only way to control symptoms, and some dogs do very well on medical therapy alone.
Starting now she'll need a low protein diet (Hills L/d diet, Royal Canin Veterinary Hepatic Formula), antibiotics to control gut flora (which are always abnormal in an animal with a shunt) as well as a medication called lactulose which absorbs some of the toxins produced because the liver isn't normal. I also recommend a supplement that includes the active ingredient in milk thistle (silymarin) as well as s-adenosyl methionine. A product called Denamarin has both active ingredients and has been tested numerous times to make sure it is effective. These supplements help the liver heal and actually take over some of the liver's function so it is less stressed.
So I highly recommend letting them try and diagnose it with imaging studies and if it's single shunt try treating it with tying it off.
If it's multiple vessels then give her a try with medical therapy.
You won't know until you try.
I'll give you a link which discusses the different shunts as well as surgery and medical treatment which I hope will be helpful for you:
And here's another that is a little more about medical treatment:
As far as costs go they will vary widely depending upon whether she needs surgery, and how complicated the surgery is, or if she just has the imaging studies. It will also depend upon how much aftercare she needs and how long she needs to be hospitalized after surgery. I would plan on anywhere from a couple thousand to $4,500+.
This isn't something that can be done at a general practice clinic, the imaging studies require specialized equipment and so does the surgery.
I hope I've addressed your questions, please let me know if you have any further concerns.