What would cause low triglycerides yet high ALT liver level?

Abetalipoprotinemia. A rare genetic condition causing low ldl, and triglyceride levels, due to a deficiency in an enzyme called "mtp" . Usually presents early in life with bad fatty diarrhea (steatorrhea) and fat accumulation in the liver . Fat in the liver ( fatty liver) can raise the liver function tests. Danger here is malabsorption of fat soluble vitamins a, d, e and k. Vit e def. Can cause neurologic symptoms.
Viral hepatitis? Both hepatitis b and hepatitis c can be causes. Excessive alcohol consumption can also do this. "fatty liver" is often associated with metabolic syndrome and elevated lipids, but some people can have lower triglycerides. There are a number of other causes of hepatitis as well. You need to see your doctor for a full evaluation.