Zip Code 23803 Population. 23803 is located in the state of Virginia in the Richmond metro area. Zip code 23803 is primarily located in Chesterfield County. Portions of 23803 are also located in Dinwiddie County.The official postal service name used for 23803 is PETERSBURG, Virginia.ip Code 23803 Area Codes. 23803 is located in the state of Virginia in the Richmond metro area. Zip code 23803 is primarily located in Chesterfield County. Portions of 23803 are also located in Dinwiddie County.
Cytomel (T3) is rarely prescribed on its own to address thyroid problems; it is usually prescribed with T4. In the past, cytomel was a scheduled treatment for obesity; however, an increase in heart complications and cardiac stress forced withdrawal of T3 for that application.
TSH stimulates the production and release of T4 (primarily) and T3 from the thyroid gland. Most of the T4 and T3 circulates in the blood bound to protein, while a small percentage is free (not bound). Blood tests can measure total T4, free T4, total T3, or free T3. The total T4 test has been used for many years, but it can be affected by the amount of protein available in the blood to bind to the hormone. Free T4 is not affected by protein levels and is the active form of thyroxine. The free T4 test is thought by many to be a more accurate reflection of thyroid hormone function and, in most cases, its use has replaced that of the total T4 test.