My 5 year old has joint pain, low grade fevers, and recently showed a "low tsh level"...his pediatrician told me this was hypothyroidism (As an RN, I thought low tsh indicated hyperthyroidism) and she is sending him to an endocrinologist with a diagnosis of "autoimmune thyroiditis"...I am confused, as it is my understanding that thyroiditis was associated with high level tsh...Are low TSH levels associated with thyroiditis? How did she make this diagnosis without his T3, T4, and antithyroglobulin levels?