The Underactive Thyroid.
Hypothyroidism is most commonly due to an autoimmune mechanism.
The autoantibodies are particularly common in insulin-dependent diabetics. Parietal cell antibodies and thyroid microsomal antibodies are often present before changes and dysfunction are found in their respective organs. Some patients may have both hypothyroidism and pernicious anemia. Hepatitis, celiac disease, or diabetes mellitus may also be associated with autoimmune thyroiditis. Simply, hypothyroidism refers to a condition in which the amount of thyroid hormone in the body is below normal.