The thyroglobulin antibody level cannot be too low. 

Thyroid peroxidase (TPO) antibodies are autoantibodies, which means the body mistakenly produces these antibodies that act against a normal protein, TPO. As such, thyroglobulin antibodies usually indicate an autoimmune disease. TPO antibodies are present in roughly 90% of people with Hashimoto's thyroiditis and in half to three-quarters of people with Graves' disease. Thyroglobulin antibodies may be detectable in people without symptoms of thyroid hormone imbalance (subclinical hypothyroidism). When hypothyroidism causes symptoms, it may cause weakness and fatigue, cold intolerance, shortness of breath, weight gain, constipation, cognitive problems, dry skin, hoarseness, and swelling (edema). In about 10% of cases, TPO antibodies will be detectable in non-autoimmune thyroid disease such as pernicious anemia and type 1 diabetes mellitus.

Some specific causes of thyroid peroxidase (TPO) antibodies are:

• Hashimoto's thyroiditis/chronic autoimmune hypothyroidism
• Goitrous autoimmune thyroiditis 
• Atrophic autoimmune thyroiditis
• Grave’s disease
• Differentiated thyroid carcinoma
• Subclinical hypothyroidism
• Pregnancy (abnormal)
• Neonatal period (transient)
• Postpartum thyroiditis
• Painless (silent) thyroiditis