I'm asking this for a friend, not me... no really, I AM asking this for a friend!

He's one of these "aah, I'll tough this out"-kind of guys, but now I'm getting a bit worried about him. I finally bullied him into seeing his dr, but he hasn't got any conclusive results yet. I see many of you have experience with thyroid issues so I wanted to just throw this out and see if anybody has any ideas.

Normally he's a fit, slightly obsessive about training, guy in his early fifties. A bit heavy but in good shape. About 6 weeks ago he was biking home and "bonked", said he just ran flat out of energy. The next week or so it felt like a cold or the flu. Then he started saying that his throat was still swollen, and suspected it was his thyroid, he's had problems with it before. For the past few weeks he's been so tired and weak that he's barely managed to drag himself to work, and has called in sick several days.

Last time he had thyroid problems he had a zillion tests, most of which didn't show anything, but he took tyroksin (?) for a while anyway which helped a bit. Now he has high cholesterol and the dr wanted him to try taking nitroglyserine. His family has a history of heart disease. My own father had fatigue as almost his only symptom before needing a five-double bypass.

He's scheduled for x-rays, CT and ultrasound. Any of you have any other ideas on what this could be?