Response of the free alpha-subunit to GnRH distinguishes individuals with 'functional' from those with permanent hypogonadotropic hypogonadism.
The aim of this study was to compare the responses of pituitary gonadotropins and the free alpha-subunit (FAS), measured by sensitive immunofluorometric assays at 0, 30 and 60 min after 100 microg GnRH i.v. in a group of 32 normal prepubertal boys (NB) and a group of 17 adult males with complete hypogonadotropic hypogonadism (HH). At time 0 min, medians of the serum levels of LH, FSH and FAS were not different in both groups. At 30 min (29.81 and 8.56 pmol/l) and 60 min (24.10 and 7.74 pmol/l) as well as peak levels (29.76 and 8.56 pmol/l), 'deltas' (peak minus baseline; 25.89 and 0.34 pmol/l) and 'fold'-increase (peak divided by baseline; 7.0-fold and 1. 6-fold), the medians were significantly higher in NB than in HH, respectively. There were fewer overlapping values of FAS between the 2 groups and they occurred in only 4% of the total number of subjects when 'fold' was considered. The measurement of FAS by a very sensitive immunofluorometric assay, after GnRH, distinguishes responses of NB from those of adult men with HH, that is of functional from permanent HH.
Mainieri
A S
AS
Serviço de Endocrinologia do Hospital de Clínicas de Porto Alegre, RS, Brazil.
Viera
J G
JG
Elnecave
R H
RH
D000293:Adolescent; D000328:Adult; D002648:Child; D015200:Fluoroimmunoassay; D005640:Follicle Stimulating Hormone / Q000097:blood; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone; D006801:Humans; D007006:Hypogonadism / Q000097:blood / Q000175:diagnosis*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male
D015292:Glycoprotein Hormones, alpha Subunit; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone