Well, Vitamin D IS a fat soluble vitamin. This means that it is stored in your fat cells and not flushed out....you CAN ingest too much, which means it can be toxic....but I don't read where is is converted to testosterone. You are right about the parathyroid....can you tell me what your reference is from regrding the conversion to testosterone?
This is a quote from that web page.
" Vitamin D is a prohormone with several active
metabolites that act as hormones. In the skin,
previtamin D3 is synthesized photochemically
from 7-dehydrocholesterol and is slowly
isomerized to vitamin D3, which is removed by
vitamin D-binding protein. In the liver, vitamin
D3 is converted to 25(OH)D3, the major
circulating form. It passes through the
enterohepatic circulation and is reabsorbed from
the gut. Principally in the kidneys, it is further hydroxylated to the much more metabolically active form, 1,25(OH)2D3 (1,25-dihydroxycholecalciferol, calcitriol, vitamin D hormone). The main function of vitamin D hormone is to increase calcium absorption from the intestine and promote normal bone formation and mineralization. These functions are mediated by a vitamin D receptor that is a transcription factor, which is instrumental in turning on a panoply of genes that express the biologic activity of vitamin D hormone. The critical 1-hydroxylation of 25(OH)D3 is strongly stimulated by parathyroid hormone (PTH) and, independently of PTH, by hypophosphatemia. The actions of vitamin D and its metabolites are summarized in Table 3-1."....................