Hi valeriejo. Elevated levels of Thyroid Peroxidase antibodies (also known as Antithyroid Microsomal antibodies) are associated with an autoimmune disorder called "Hashimoto's Thyroiditis." The antibodies attack the thyroid gland and, generally, result in hypothyroidism.
Symptoms may swing between Hypo and Hyper or a combination of both. The antibodies sometimes flare-up, temporarily increasing the symptoms.
Selenium (100 mcg/day) may help fight the antibodies, and also helps your body metabolize thyroid hormone. A Peruvian herb called Maca (rich in Selenium, among other things) may also help.
Antibodies also have a tendency to make your TSH value fluctuate, so it is a good idea to have a complete thyroid blood test panel completed, preferably by an Endocrinologist who specializes in thyroid disease, including Free T3 and Free T4. The Free hormone levels show what is available for the body to use and help indicate how well your body is metabolizing hormone.
If you've not yet had a chance, you may want to read through our Information Archive thread. This 3-page thread includes symptoms lists, notes about antibodies, thyroiditis, supplements including Selenium & Maca, and much more.