In an earlier clinical study, significant increases in serum parathyroid PTH concentrations, along with minimal but significant decreases in serum calcium (Ca) levels, were observed in osteoporotic women treated for six months with conjugated equine estrogen [29]; this pointed to an indirect effect of estrogen on PTH secretion, mediated through mild hypocalcemia caused by estrogen-related inhibition of bone resorption [29]. Here, PTH is linked to Hypocalcemia.