My liver enzymes are high. at what level does it become serious?

Depends: It depends on the underlying cause of the liver enzyme elevations. The most common cause these days is a one to five fold increase in liver enzymes due to fatty liver disease, however other causes like alcohol, autoimmune disease, hepatitis, etc can cause elevations. See a hepatologist to determine the cause. If your enzymes are over 500, it is concerning, depending on other factors and lab values.