How does the author use foreshadowing in McTeague: A Story of San Francisco?

In the beginning of the novel, McTeague obsessively desires a gold tooth as proof of his status in society, and once he possesses it is thoroughly content. When his decline begins, he clings to the tooth and insists on keeping it in each of his ever-more-cramped apartments. Losing it is for him a shocking catastrophe that foreshadows his later tragedy.