The study evaluates whether hypothyroid patients requiring elevated doses of levothyroxine to maintain a euthyroid state are at increased risk of having celiac disease. It also attempts to determine if there is a threshold level of levothyroxine needed to maintain a euthyroid state in patients with hypothyroidism that should prompt serologic testing for celiac disease.

This study is looking at whether hypothyroid patients who require above 125 mcg/day (or >1.5mcg/kg/day) of levothyroxine are more likely to have celiac disease than those who require smaller doses. It also looks to see if the prevalence of celiac disease in hypothyroid patients who require elevated doses of levothyroxine is high enough to warrant screening in that population.

Inclusion Criteria:

• Patients with the diagnosis of hypothyroidism that require thyroid replacement therapy.

Exclusion Criteria:

• Surgical resection of thyroid tissue, neck irradiation, radioactive iodine therapy, prior medical treatment with lithium, methimazole, propylthiouracil, ethionamide, amiodarone, or sunitinib, prior serologic testing for celiac disease.

Patients with hypothyroidism who take thyroid replacement therapy