Thyroglobulin (Tg) is a 660 kDa, dimeric protein produced by and used entirely within the thyroid gland. Tg is used by the thyroid gland to produce the thyroid hormones thyroxine (T4) and triiodothyronine (T3). tyroglobulin levels in the blood can be used as a tumor marker for certain kinds of thyroid cancer (particulary papillary or follicular thyroid cancer). Thyroglobulin levels in the blood can also be elevated in cases of Graves' disease.
The normal range for Tg is between(in men) 100ng/dl - 2000ng/dl. At 64.9 your is considered fairly low (assuming yours was in units-ng/dl)