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.
And Hammer Studios produced three Robin Hood movies in the 1950s and 1960s: Men of Sherwood Forest (1957), Sword of Sherwood Forest (1960), and A Challenge for Robin Hood (1968). The 1938 film had a sequel of sorts, Robin and Marian (1976), with Sean Connery and Audrey Hepburn as middle-aged lovers. And Kevin Costner starred as the title character in Kevin Reynolds' Robin Hood: Prince of Thieves (1991).