Methods for differentiating destructive thyroiditis from other pathological conditions

A method for measuring monoiodotyrosine and/or diiodotyrosine in a subject, comprising:

• collecting a test sample from the subject, wherein the test sample is not from the thyroid gland of the subject;
• and
• obtaining a first test measurement of monoiodotyrosine, a second test measurement of diiodotyrosine, or the first test measurement and the second test measurement in the test sample, wherein the first test measurement is higher than a first control measurement of monoiodotyrosine in a first corresponding sample collected from a first unaffected body or a first non-destructive thyroiditis disease-affected body or higher than a first cutoff value, and wherein the second test measurement is higher than a second control measurement of diiodotyrosine in a second corresponding sample collected from a second unaffected body or a second non-destructive thyroiditis disease-affected body or higher than a second cutoff value.