Hypothyroidism is a condition where your thyroid (a gland in your neck) stops producing thyroxine. Now, this probably doesn't mean much to you - but you may have heard of diabetes or Addison's disease (JFK had this, interestingly) - and while insulin and adrenaline, or their defiency, can only cause changes in certain tissues in the body, thyroxine can effect all of them - reproductive, digestive, muscle tone, brain chemistry, ect. However, hypothyroidism isn't fatal, unlike untreated diabetes or hypoadrenalism.

Hypothyrodism, in general, effects "older" women - women who have had children or women entering or leaving menopause. This is because hormone fluctuations such as the change of life or childbirth can instigate an autoimmune response, where the body attacks the thyroid gland.

However, this disease can effect anyone, regardless of age or gender, as even babies can be born with hypothyroidism (cretinism).

As exciting as your body attacking your organs sounds (I imagine it was very CGI inside your imaginations for a second) the onset of hypothyroidism is a very gradual disease. Other reasons for developing hypothyroidism is the treatment for hyperthyroidism involving radiation therapy (typical), and other conditions effecting the pituitary gland and/or hypothalmus.

My experience with hypothyroidism started when I was a young teenager, and after a sports injury that healed up well, I began to feel generally tired, cold, and I put on weight. This was during the summer holidays - a period I think of as lost time, as it was almost exclusively spent sleeping - and after seeing the doctor and undergoing tests, I was put on a low dose of thyroxine (levothyroxine, 25 micrograms). Unfortunately this didn't do much for me, but the treatment had to be slow or I'd risk developing hyperthyroidism - which is much more dangerous than having too little thyroxine in your system.

I missed so much school that I had to drop out: I couldn't concentrate in class, I kept falling asleep, I'd feel just terrible. I remember walking down the corridor in between classes and feeling so heavy - as if I was dragging along a dead twin inside me, was the thought I had. Meanwhile I was undergoing more and more tests - blood tests, MRIs, CTs, x-rays, insulin tolerance tests (both long and short), psychological tests, ultrasounds on my ovaries - it was hell. I was constantly bruised or pinpricked and I wasn't feeling any better for it. I was bullied by my psychologist. My endocrinologist scratched his head. My hair started to fall out, so I had to cut it short. I had to deal with my parents' disappointment over my grades and school situation. I also had to come to terms with the fact that I can never have children.

In a last bid to try and get some results from my testing, I was put on x3 of my usual dose of thyroxine. I don't really remember much about this - I couldn't sleep, weight dropped off me and I became gaunt, I had conversations with people that I didn't remember (and didn't make much sense), and I lost the ability to concentrate - couldn't read, couldn't watch TV, couldn't do anything. 5 years later, I am now on a much lower dose of thyroxine and I am slowly beginning to get back to normal.

All in all, I think hypothyroidism deserves more awareness than it currently has. A problem with hypothyroidism is the symptom of depression - hypothyroidism can cause depression by messing up healthy brain chemistry, but frankly, hypothyroidism is a depressing illness all on its own. While this is not a fatal illness, it is a life-changing one, and personally I experienced next to no support from the education system, my endocrinologist, or my parents. I know if I had had diabetes instead, the situation would have been very different.

If you have any symptoms I've mentioned here - and there's a lot I haven't, but a quick Google should search them out - it's worth getting tested. Subclinical hypthyroidism (hypothyroidism that isn't "bad enough" to need treatment) is always worth keeping an eye on, because things can change very quickly in response to stress, pregnancy, or illness/injury (autoimmune problems often start with an injury or a flu-like illness). It's just a quick blood test to make sure you're healthy.