Many conditions can lead to hypothyroidism; it is extremely common in our world today. If statistics are correct, most of the readers of this book with a thyroid problem will have hypothyroidism. In fact it is estimated that in 2009, 10 million people in the United States had hypothyroidism. Symptoms of hypothyroidism reflect a slowing down of the me-tabolism. These may include extreme tiredness, problems losing weight, problems adjusting and tolerating cold temperatures, depression, constipation, decreased sex drive, and problems with memory and irritability.