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 appears in Sir Walter Scott's Ivanhoe and many other books, stories and movies. Most Robin Hood stories are set in the era of 1100 - 1300 A.D., and in many he is a defender of the real-life King Richard the Lion-Hearted and enemy of the usurper, King John. Much like King Arthur, Robin is a fictional figure who may have been loosely based on a real person or persons. Robin Hood has been played in the movies by Errol Flynn (1938), Kevin Costner (1991) and Sean Connery (1976), among others; he was portrayed as a fox in the 1973 Disney animated version of the tale.