When pollution is caused by nutrients and fertilizers, this is called nutrient pollution, and it leads to an overproduction of algae and other aquatic plants. This overabundance of plants and algae causes problems, because they cover the water surface and prevent sunlight from reaching the plants underwater.
Reverse T3 is actually an antithyroid -- T3 is the active thyroid that goes to the cells and stimulates energy and metabolism. Reverse T3 is a mirror image -- it actually goes to the receptors, sticks there, and nothing happens. So it blocks the thyroid effect. Reverse T3 is kind of a hibernation hormone, in times of stress and chronic illness, it lowers your metabolism.
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.