Monitoring your serum ferritin and GGT levels and taking steps to lower them if they’re too high, you can avoid serious health problems. Virtually all men and postmenopausal women are at risk for iron overload due to inefficient excretion. Left untreated, it can contribute to cancer, heart disease, neurodegenerative diseases and other chronic health problems. GGT is a liver enzyme involved in glutathione metabolism and the transport of amino acids. GGT can be used as a screening marker.