CALCA and hypogonadism: Hyperprolactinemia (in this case associated with antipsychotic medication use) suppresses the release of GnRH from the hypothalamus, which in turn causes hypogonadism that contributes to bone loss. Recent research has uncovered additional hormonal factors that may disrupt bone homeostasis, such as reduced calcitonin plasma levels in hyperprolactinemic women, or elevated parathyroid hormone-related peptide levels in the plasma of women with prolactinoma