No, the thyroxine concentration may not always be increased. However, these T4 values are usually at the upper end of the reference range. There are a number of potential reasons for this. Thyroxine levels in the blood naturally fluctuate throughout the day, depending on the metabolic needs of the cat.
The Adventures of Robin Hood is a 1938 American Technicolor swashbuckler film, produced by Hal B. Wallis and Henry Blanke, directed by Michael Curtiz and William Keighley, that stars Errol Flynn, Olivia de Havilland, Basil Rathbone, and Claude Rains.
Robin arrived in Tortola on October 10th 1965 on his 28 sloop with his wife and family (see also the Jill Tattersall Interview in this collection for details about the trip) to take up the post of Government Surgeon (from 1965-76).