Resistance to @entity935 agonists can be defined with respect to failure to normalize PRL levels and failure to decrease @entity5 size by > or = 50%. Using these definitions, failure to normalize PRL levels is seen in 24% of those treated with @entity2847 , 13% of those treated with @entity4088 and 11% of those treated with @entity9229 . Failure to achieve at least a 50% reduction in @entity5 size occurs in about one-third of those treated with @entity2847 and 10-15% of those treated with @entity4088 or @entity9229 . Studies of in vitro cell preparations show that the D2 receptors of resistant @entity5 are decreased in number but have normal affinity. Treatment approaches for resistant @entity1 include switching to another @entity935 agonist and raising the dose of the drug as long as there is continued response to the dose increases and no adverse effects. Transsphenoidal surgery can also be done. If fertility is desired, @entity4082 , gonadotropins, and @entity1176 are also options. If fertility is not desired, @entity172 replacement may be used unless there is a macroadenoma, in which case control of @entity5 growth is also an issue and @entity935 agonists are generally necessary. However, in many cases modest or even no reduction may be acceptable long-term as long as there is not @entity5 growth. Hormone replacement ( @entity172 or @entity251 ) may cause a decrease in efficacy of the @entity935 agonist so that it must be carried out cautiously. Reduction of endogenous @entity172 , use of selective @entity172 receptor modulators, and aromatase inhibitors are potential experimental approaches.

XXXX resistance of prolactinomas.

@entity1 :: ('9606', 'Species') :: ['patients'] @entity2847 :: ('MESH:D001971', 'Chemical') :: ['bromocriptine'] @entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity251 :: ('MESH:D013739', 'Chemical') :: ['testosterone'] @entity9229 :: ('MESH:C047047', 'Chemical') :: ['cabergoline'] @entity935 :: ('MESH:D004298', 'Chemical') :: ['dopamine'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'tumors'] @entity4082 :: ('MESH:D002996', 'Chemical') :: ['clomiphene'] @entity4088 :: ('MESH:D010479', 'Chemical') :: ['pergolide'] @entity1176 :: ('MESH:D007987', 'Chemical') :: ['GnRH']
@entity935 :: (MESH:D004298,Chemical) :: ['Dopamine']
