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Prolactin secretion after surgery or bromocriptine treatment of prolactinoma
Abstract:
In prolactinoma patients, the unresponsiveness of prolactin (PRL) to dynamic tests with thyrotropin-releasing hormone (TRH) or dopamine agonist or antagonist drugs suggests that the disease is caused by the failure of central dopaminergic inhibition. The absence of PRL secretory response to dopamine or TRH in prolactinoma patients also may be an effect of the disease. Twenty-six women diagnosed by dynamic tests and radiologic examination as having PRL-secreting adenoma were treated surgically (15) or with bromocriptine (11) and their condition was evaluated one to three years later by TRH, nomifensine, and domperidone tests. Basal PRL levels decreased after surgery and bromocriptine treatment. At the time of the follow-up study, PRL levels were elevated in six of the 15 surgically treated patients and in six of the 11 treated with bromocriptine. Thyrotropin-releasing hormone, nomifensine, and domperidone produced standard PRL responses in normoprolactinemic patients but not in hyperprolactinemic patients. These results indicate that the alteration of TRH or dopaminergic receptors in the regulation of PRL secretion in prolactinoma is related to the disease and disappears when the tumor is removed or treated successfully with bromocriptine.
Insights
Prolactinoma treatment with surgery or bromocriptine normalized prolactin (PRL) levels in most patients. Dynamic tests revealed that altered TRH and dopamine receptor function in prolactinoma resolves with successful tumor treatment.
Area of Science:
- Endocrinology
- Neuroendocrinology
- Oncology
Background:
- Prolactinomas, pituitary tumors secreting prolactin (PRL), often show abnormal PRL response to dynamic tests.
- This unresponsiveness may stem from impaired central dopaminergic inhibition or be a consequence of the disease itself.
Purpose of the Study:
- To evaluate the long-term effects of surgical or bromocriptine treatment on PRL secretion and dynamic test responses in prolactinoma patients.
- To determine if the observed alterations in PRL regulation are inherent to the disease or reversible upon successful treatment.
Main Methods:
- Twenty-six women with prolactinoma underwent either surgery (15) or bromocriptine treatment (11).
- Follow-up evaluations one to three years later included basal PRL levels and dynamic tests using thyrotropin-releasing hormone (TRH), nomifensine, and domperidone.
Main Results:
- Both surgical and bromocriptine treatments reduced basal PRL levels.
- At follow-up, hyperprolactinemia persisted in 6/15 surgically treated and 6/11 bromocriptine-treated patients.
- Dynamic tests showed normal PRL responses in normoprolactinemic individuals but not in those with persistent hyperprolactinemia.
Conclusions:
- The observed alterations in TRH and dopaminergic receptor function in prolactinoma are linked to the active disease state.
- Successful treatment, either surgical or pharmacological, leading to normalization of PRL levels, resolves these regulatory abnormalities.