Pharmacologic resistance in prolactinoma patients

Mark E Molitch*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

136 Scopus citations

Abstract

Pharmacologic resistance to dopamine agonists is defined here as failure to normalize PRL levels and failure to decrease macroprolactinoma size by ≥50%. Failure to normalize PRL levels is found in about one-quarter of patients treated with bromocriptine and 10-15% of those treated with pergolide or cabergoline. Failure to achieve at least a 50% reduction in tumor size occurs in about one-third of those treated with bromocriptine and 10-15% of those treated with pergolide or cabergoline. The cause of dopamine resistance is primarily a decrease in D2 receptors but the receptors have normal affinity for dopamine. Treatment approaches for patients resistant to dopamine agonists include changing to another dopamine agonist and increasing the dose of the drug as long as there is continued response to the dose increases and no adverse effects with higher doses. Transsphenoidal surgery is also an option. Clomiphene, gonadotropins, and GnRH can be used if fertility is desired. For those not desiring fertility, estrogen replacement may be used unless there is a macroadenoma, in which case control of tumor growth is also an issue and dopamine agonists are generally necessary. In many patients modest or even no reduction in tumor size may be acceptable as long as there is not tumor growth. Hormone replacement (estrogen or testosterone) may cause a decrease in efficacy of the dopamine agonist so that it must be carried out cautiously. Reduction of endogenous estrogen, use of selective estrogen receptor modulators, and aromatase inhibitors are potential experimental approaches.

Original languageEnglish (US)
Pages (from-to)43-52
Number of pages10
JournalPituitary
Volume8
Issue number1
DOIs
StatePublished - Jan 1 2005

Keywords

  • Bromocriptine
  • Cabergoline
  • Dopamine
  • Prolactin
  • Prolactinoma
  • Resistance

ASJC Scopus subject areas

  • Endocrinology

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