I am not sure if I answer it clearly as this is not in my lectures, I will try to explain as I understand.
The use of the AST:ALT ratio as a hemolytic marker, because it has an inverse association with the hemoglobin level. Subjects with sickle cell disease would have higher AST levels due to the hemolytic nature of the condition. This is the first report highlighting the AST:ALT ratio in sickle cell disease.
According to Chalasani et al, (FDA guideline), AST is found in red cells, but not ALT. ALT is exclusively found in cytoplasm, but AST is in both mitochondria and cytoplasm. The elevated activities of both enzymes are due to cell destruction or membrane leakage.
Hence, the AST expression in red cells and high levels of AST should indicate red cell membrane leakage, i.e. Hemolysis.