Thyroid disease is one of the most common endocrine disorders. Disorders of thyroid function include hypothyroidism and hyperthyroidism. Thyroid symptoms vary depending on the degree of under- or overproduction of thyroid hormones. Hypothyroidism symptoms (dry, brittle hair; fatigue; cold intolerance) can develop slowly over months or years. Symptoms of hyperthyroidism (increased pulse, irregular rhythm, sweating, weight loss) are generally more overt.