What causes swollen hands?

Thyroidism, any kind, doesn't cause swollen hands. I have Hypo and I never had that problem. It may be something else, and you should go consult a doctor if it starts becoming a problem. It may be that you are dehydrated, I had that happen only once when I went out running during the summer for hours without water... (Stupid move, I know... -_-') My hands puffed up and I was panicking thinking I was having an allergy attack (I never had one but one of my friends did and it was scary). But it went down when I relaxed, drank some water and took a nap. :3