Distribution of growth hormone isoforms in sera from women with normal ovarian function, galactorrhea, and normoprolactinemia.
OBJECTIVE
To demonstrate if GH concentrations and molecular heterogeneity of GH correlates with the presence of galactorrhea in normoprolactinemic women with normal ovarian function.


METHODS
Aliquots of sera from women with normal ovarian function and normoprolactinemic galactorrhea were subjected to gel filtration chromatography, and the fractions were assayed for GH by the use of radioimmunoassay. Molecular weight of isoforms was calculated on a calibration curve obtained with molecular markers. The molecular variants were characterized on the basis of elution volume, molecular weight (MW), and partition coefficient.


RESULTS
Basal serum GH levels were moderately elevated in all six normoprolactinemic 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 isoforms. This pattern was different from that obtained in sera from normal women without galactorrhea who presented a predominance of heavier (> 60 kd) isoforms eluted before the GH labeled standard. The monomeric forms were present in less proportion but there was no significant difference as compared with galactorrheic group.


CONCLUSIONS
Our investigation demonstrated elevated GH basal serum levels is normoprolactinemic women with galactorrhea, and chromatography in gel showed a low proportion of the large MW GH variants associated with a higher proportion of the dimeric forms and very low MW forms of GH. This is different from normal women without galactorrhea who had a predominance of heavier MW GH variants and lesser proportion of < 16 kd isoforms. It is concluded that an increased GH secretion may be responsible for abnormal lactation despite normal PRL levels in some women with normal ovarian function.
Ochoa
R
R
Endocrine Research Unit, Instituto Mexicano del Seguro Social, México City.
Mason
M
M
Fonseca
E
E
Morán
C
C
Zárate
A
A
D000328:Adult; D002850:Chromatography, Gel; D005260:Female; D005687:Galactorrhea / Q000097:blood*; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D007536:Isomerism; D010053:Ovary / Q000502:physiology*; D011388:Prolactin / Q000097:blood*; D011863:Radioimmunoassay; D012016:Reference Values
D011388:Prolactin; D013006:Growth Hormone