I just came across an excellent blog for any of you who are interested in U.S. National Archives records, and wanted to share a link to it. It is called The Twelve Key, by Claire Prechtel Kluskens, who is a senior reference and projects archivist at the National Archives and Records Administration (NARA), Washington, DC.
In my first visit to her blog I learned about the carded medical records for Mexican War volunteers in a link to an article she wrote about it for NGS Magazine in 2014, and I was able to order my great-great grandfather’s medical record from the Mexican War. According to his pension file, which I obtained years ago, he had been hospitalized when he lost a finger “in a charge made by lancers” at the Battle of Buena Vista. I am very interested to see his medical record! I’ll post it here when I receive it.
The Twelve Key website has links to Kluskens’ extensive historical and genealogical publications, as well as research guides she has produced for the National Archives, and syllabus materials for lectures. You are going to love this website!
On Granny's Trail 
Thanks!