123 - Impatto clinico e laboratoristico delle isoforme macromolecolari della prolattina

A.Marcolla, C.Dilberis, F. Dal Bosco, P. Amadori Clinical and laboratory importance of prolactin macromolecular isoforms. Macromolecular isoforms of prolactin (PRL) are classified as BigPRL and BigBigPRL (macroprolactin) on the basis of their molecular weight. They can be present in both normoprolactinemic and hyperprolactinemic human serum, and are detected by current immunometric PRL assays, causing problems in result interpretation. The aims of this review were: a) to perform a thorough, up-to-dated evaluation of the literature on the PRL macromolecular isoforms and on the ability of immunometric PRL assays to recognise BigPRL and BigBigPRL isoforms; b) to define the optimal management of macroprolactinemic samples. The results of this survey, show that hyperprolactinemia due to excess of PRL macromolecular isoforms is as common as about 20% among blood samples assayed for PRL in general clinical laboratories, although the rate may vary according to the method. Gel chromatography is the most sensitive and specific technique for detecting macroprolactin, also able of assaying BigPRL, but it is expensive and time consuming and therefore seldom used. PEG precipitation, the most employed method to discover BigBig- PRL, does not enable the recognition of BigPRL. Labs should routinely perform macroprolactin detection in hyperprolactinemic samples. Otherwise, information about the possible presence of macroprolactin should be added to the report, and the opportunity to check for macroprolactinemia should be offered. Distinction between BigBigPRL with and without anti-PRL antibodies is possible by means of several, non standardised methods, recognising the immunologic component of the molecule. However, at present, there is no certain clinical usefulness in distinguishing between BigBigPRL with or without anti- PRL antibodies, although future perspectives are reasonably imaginable.