While hypothyroidism--having an underactive thyroid--is most common in middle aged women, problems with the thyroid can happen at any age.
Changes in Energy Level
One of the most commonly reported signs of an under active thyroid is fatigue and lack of energy. However, having an overactive thyroid can also cause muscle weakness and fatigue since the body's metabolism is constantly running on overdrive.
Changes in Menstrual Cycle
Changes in the pattern of menstruation may indicate hyperthyroidism, while heavier menstrual periods may be a sign of hypothyroidism.
Unexplained Weight Changes
Unexplained weight loss may be a symptom of an over active thyroid, while weight gain is common in hypothyroidism.
Changes to Hair, Skin and Nails
Those with an under active thyroid often experience dry skin, brittle nails and may experience more than average hair loss.
Difficulty breathing or swallowing may indicate nodules on the thyroid. Many times, these nodules are benign, but a medical check should be performed to rule out thyroid cancer.