Method to Extract the "Detailed Description" Field Contents Via an API Call?

The "Detailed Description" field (in the node properties for boards and blogs (at least) is only exposed to the on-page component "Node Detailed Description". The content of this field does not generate a named text string. I do not want the component on my pages, but just want to extract the content of the field in the Properties sheet. Since it's not a named text string, is there an alternate method to extract that content? What I would like to do ultimately is to use this for the metadata Description, instead of what is placed on the page. SEO requirements generally lead to entirely different content than on-page sub-heading ("Description") text.