| Isotope studies demonstrate that acute administration of lipid-soluble oral cholecystographic contrast agents result in acute release of T4 from tissue stores, probably mainly from the liver, resulting in a transient increase the serum T4 concentration by up to 30% (Felicetta et al, 1980). Reinhardt et al (1999) have recently described an acute transient increase in serum thyroid hormone levels by up to 60% in response to the alkylating agents cyclophosphamide and ifosfamide, and have suggested that similar hormone displacement from tissue stores may be the cause. |
