<prompt> Decreased activity of type I 5-monodeiodinase could lead to which physiologic effects:-Increased plasma triiodothyronine T3Increased plasma reverse T3Decreased plasma thyroxine T4Increased TSH  <response>: Type I 5-monodeiodinase is the enzyme responsible for the peripheral conversion of thyroxine T4 to triiodothyronine T3, primarily in liver and kidney.This enzyme also participates in the breakdown of reverse T3 rT3 by converting it to 3,3-diiodothyronine. Decreased activity of type I 5-monodeiodinase will therefore decrease plasma levels of T3 and increase plasma levels of rT3 by decreasing its breakdown. Type II 5-monodeiodinase is present in the anterior pituitary and central nervous system. Conversion of T 4 to T 3 within the anterior pituitary by this enzyme is responsible for normal feedback inhibition of thyroid stimulating hormone TSH secretion. With decreased type I 5-monodeiodinase activity, plasma levels ofT4 and TSH usually stay within normal limits because the type II enzyme continues to insure normal feedback inhibition by anterior pituitary T 3. 