Macroprolactinemia: Clinical Relevance, Diagnostic and Therapeutic Approach
Issue: 3/2011
Author: Atanaska Elenkova, Mariya Yaneva, Nicolai Genov, Zdravka Abadzhieva, Georgi Kirilov, Krasimir Kalinov, Sabina Zacharieva
Abstract:
Background: Macroprolactinemia is a state of hyperprolactinemia due predominantly to presence of the high-molecular form of prolactin in the circulation. Data concerning the biological activity and the site of synthesis of macroprolactin are controversial.
Aim: The aim of the present study was to determine the prevalence of macroprolactinemia and the correlation between macroprolactin levels and clinical presentation in patients with prolactinomas.
Patients and methods: The study population consisted of 160 subjects: 80 prolactinoma patients and 80 sex-, age- and BMI – matched healthy controls. Serum macroprolactin was detected by treatment with PEG 6000. Macroprolactinemia was identified by a PRL recovery after PEG precipitation of < 40%.
Results: The prevalence of macroprolactinemia among newly diagnosed prolactinoma patients, detected by PEG-precipitation test was, 2,7% and did not differ significantly from the prevalence in age- and sex-matched healthy subjects (5%). Statistically higher prevalence of macroprolactinemia among normoprolactinemic patients can be explained by the inverted ratio of monomeric to high-molecular prolactin isoforms due to their different answer to the treatment with dopamine agonists. Significant dependence of serum monomeric form and macriprolactin levels on menstrual cycle and ovarian fulliculogenesis was found not only in subjects with true hyperprolactinemia but also in macroprolactinemic patients. In a few cases, the presence of typical hyperprolactinemia-related clinical symptoms and their disappearance after treatment with dopamine agonists suggests biological activity of macroprolactin comparable to that of the monomeric prolactin isoform. Decrease of macroprolactin levels after treatment with dopamine agonists suggests tumoral origin of the high-molecular prolactin isoform in these rare cases.
Conclusion: Although macroprolactinemia is considered to be a benign condition, pituitary imaging, dopamine agonist treatment, and prolonged follow-up may be necessary in certain cases. An individualized approach to the management of patients with macroprolactinemia should be applied.
