If you had to choose one gland and/or resulting hormone to live without, which one would it be and why?

If I had to choose to live without one gland it would most likely be the thyroid gland.  I say this because my thyroid gland doesn't actually work anymore, but with medication, I'm now able to lead a completely normal life.  I'll explain below why this is.

The thyroid gland is responsible for producing two important hormones.  The first hormone is thyroxine, commonly known as T4, and this hormone is transformed into triiodothyronine, commonly known as T3.

The hormones produced by the thyroid gland control our metabolism, and are important because they dictate how quickly our cells work.  When our thyroid glands produce too much or too little of these hormones, things start to go wrong. 

I've personally got too little of these hormones, meaning that I have to endure symptoms such as tiredness, inability to deal with cold temperatures, dry skin, depression, and if not treated, death.  These are the symptoms someone would experience if they have to live without a thyroid gland.

Treatment

Luckily, an under-active - or lack of - thyroid gland can be treated with medication known as Levothyroxine.  This is a synthetic version of the thyroxine hormone that's produced by the thyroid gland under normal circumstances.

So there you have it.  I'd choose to live without a thyroid gland because I'm pretty much doing so already, and feel just fine.  Having said that, if there was no medication available, I'd be in serious trouble.

Here's a brief video explaining in more detail what the thyroid gland actually does: