DISTRIBUTION OF GROWTH-HORMONE ISOFORMS IN SERA FROM WOMEN WITH NORMAL OVARIAN-FUNCTION, GALACTORRHEA, AND NORMOPROLACTINEMIA

Objective: To demonstrate if GH concentrations and molecular heterogen eity of GH correlates with the presence of galactorrhea in normoprolac tinemic women with normal ovarian function. Design: Aliquots of sera f rom women with normal ovarian function and normoprolactinemic galactor rhea were subjected to gel filtration chromatography, and the fraction s were assayed for GH by the use of radioimmunoassay. Molecular weight of isoforms was calculated on a calibration curve obtained with molec ular markers. The molecular variants were characterized on the basis o f elution volume, molecular weight (MW), and partition coefficient. Re sults: Basal serum GH levels were moderately elevated in all six normo prolactinemic women exhibiting galactorrhea. Chromatographic study of sera from these normoprolactinemic women showed the predominance of 40 to 50 kd molecular forms of GH as well as some very low MW GH isoform s. This pattern was different from that obtained in sera from normal w omen without galactorrhea who presented a predominance of heavier (>60 kd) isoforms eluted before the GH labeled standard. The monomeric for ms were present in less proportion but there was no significant differ ence as compared with galactorrheic group. Conclusions: Our investigat ion demonstrated elevated GH basal serum levels in normoprolactinemic women with galactorrhea, and chromatography in gel showed a low propor tion of the large MW GH variants associated with a higher proportion o f the dimeric forms and very low MW forms of GH. This is different fro m normal women without galactorrhea who had a predominance of heavier MW GH variants and lesser proportion of <16 kd isoforms. It is conclud ed that an increased GH secretion may be responsible for abnormal lact ation despite normal PRL levels in some women with normal ovarian func tion.