I have hypothyroidism, and these were some of the symptoms that I experienced:
Moodiness, hair loss, brain fogginess, heart palpitations (very scary), being very cold - low body temperature, dry and cracking skin, fatigue, low-energy, exhaustion. Each person will have different symptoms, though.

The symptoms of an under active thyroid, or hypothyroid, can vary, but often include tiredness, sensitivty to cold, dry skin, brittle hair and fingernails, and depression.

An under active thyroid can be diagnosed with a simple blood test. It's treated by giving synthetic thyroid hormone to the patient. Thyroid hormone levels must be checked on an ongoing basis.

The symptoms of underactive thyroid, also known as, hypothyroidism are related to the slowing down of the metabolic rate of everything in your body. Come changes are apparent earlier than others.

Early symptoms include:
• Feeling slowed down
• Constipation
• Weight gain
• Fatigue
• Hair loss
• Depression
• Being more sensitive to cold
• Dry skin
• Thin, brittle fingernails
• Joint or muscle pain
• Change menstrual periods

If left untreated, the following symptoms may occur:
• Puffy face, hands, and feet
• Hoarseness
• Decreased taste and smell
• Slow speech
• Thickening of the skin
• Thinning of eyebrows

Hypothyroidism can go undiagnosed and thus untreated for long periods of time, because the early symptoms tend to come on slowly and/or may be attributed to many other things. In many cases, hypothyroidism is found on routine blood testing prior to the development of any symptoms.