Why thyroglobulin level are not elevated in thyrotoxicosis fictitious and they are elevate in all other causes of hyperthyroidism?

Why thyroglobulin level are not elevated in thyrotoxicosis fictitious and they are elevate in all other causes of hyperthyroidism ?

Endo v/s exo

Endogenously produced T3/T4 are stored as Thyroglobulin in the thyroid.

Thyrotoxicosis Factita means exogenous intake of T3/T4. Thyroglobulin doesn’t rise because there is no excess production by the gland.