Sexual dimorphism in circulating monomeric and dimeric inhibins in normal boys and girls from birth to puberty.

BACKGROUND AND OBJECTIVE: Inhibins are peptides, mainly of gonadal origin, that suppress FSH production. Dimeric forms of inhibin (A and B) have been proposed as peripheral markers of Sertoli and granulosa cell function. The aim of this study was to establish the relationship between circulating dimeric and monomeric inhibins, and gonadotrophins and sex steroids, in normal boys and girls from birth to puberty. SUBJECTS: One hundred and forty-six normal children (females: 57; males: 89) were studied. MEASUREMENTS: Serum LH and FSH were measured by an immunofluorometric assay. Serum oestradiol and testosterone were measured by radioimmunoassay. Serum inhibin A and B, and Pro-alphaC, were measured by specific two-site enzyme-linked immunosorbent assays. RESULTS: In boys from birth to 6 months of age, the mean serum inhibin B concentration was as high (477 +/- 53.7 ng/l) as that found at puberty (400 +/- 70.2 ng/l). After the first year, inhibin B gradually decreased to reach its lowest concentration (153 +/- 23.6 ng/l) at age 4-6 years. At approximately age 10, it rose progressively to reach pubertal concentrations. Pro-alphaC showed a similar pattern but at lower concentrations. Inhibin A was not detected at any age. In girls from birth to 6 months, inhibin B levels (83.0 +/- 18.3 ng/l) were approximately 50% lower than those found at puberty (181 +/- 25.7 ng/l). After 6 months of age, these levels dropped (17.5 +/- 1.6 ng/l) and remained low until the prepubertal years. Thereafter, they increased to pubertal concentrations. The serum inhibin A concentration after birth (29.9 +/- 8.7 ng/l) was similar to that found at puberty (18.3 +/- 5.7 ng/l); after 6 months, it fell to undetectable levels until the prepubertal years. CONCLUSION: The sex difference in serum levels of gonadotrophins is associated with sex differences in the levels and proportions of circulating dimeric and monomeric inhibins.

Evaluation of disease activity by IGF-I and IGF binding protein-3 (IGFBP3) in acromegaly patients distributed according to a clinical score.

UNLABELLED: To facilitate the estimation of acromegalic activity a prospective study was done comparing, against a clinical score, the effectiveness of serum IGF-I, IGFBP3 and the IGF-I/IGFBP3 molar ratio. Sixty nine observations were distributed in three groups: Group I=patients before surgery; group II=patients improved but still clinically active; group III=patients clinically inactive. Suppression of serum GH levels one hour after an oral glucose load was in agreement with the clinical score in 21/22 observations. Increases in serum IGF-I and IGFBP3 levels were similarly frequent: both 100% in group I, 80% and 95% in group II, 9% and 36% in group III, respectively. The frequency of abnormal molar ratios was 95%, 40% and 0% in the same groups. Log IGF-I, log IGFBP3, and log molar ratio correlated significantly with the clinical scores (r=0.873, r=0.692, and r=0.829, respectively). CONCLUSIONS: The IGF-I/IGFBP3 molar ratio was not better than either IGF-I or IGFBP3 in detecting activity in the three groups of patients studied. Both IGF-I and IGFBP3 appear comparably useful for the diagnosis and follow-up of acromegalic patients. Since IGF-I is a more biologically meaningful parameter it might be preferable.

Persistence of autonomous ovarian activity after discontinuation of therapy for precocious puberty in McCune-Albright syndrome.

OBJECTIVE: The aim of this study was to evaluate the possibility of persistence of autonomous ovarian activity in girls with McCune-Albright syndrome (MAS) after withdrawal of medroxyprogesterone therapy administered for precocious puberty. DESIGN, SETTING, AND PARTICIPANTS: Five girls with MAS were followed-up 1.2 to 8.5 years after the end of treatment. The girls underwent luteinizing hormone-releasing hormone (LH-RH) tests, estradiol (E2) basal measurement, and pelvic ultrasound two times in the follow-up period. RESULTS: Menses resumed in four of five girls, 1.4 +/- 0.9 years after the end of treatment, at chronologic age of 11.3 +/- 1.3 years. Cycles for all girls were irregular. Three patients presented inadequate E2 levels (from 56 to 320 pg/mL) associated with low or absent gonadotropin response to LH-RH tests. The pelvic ultrasound showed ovarian cysts at the time of the study. CONCLUSION: These hormonal and ultrasonographic findings provide evidence of persistence of autonomous ovarian activity in some young women with MAS.

Hormonal parameters and testicular volume in children and adolescents with unilateral varicocele: preoperative and postoperative findings.

Preoperative and postoperative testicular volume, serum testosterone, follicle-stimulating hormone and luteinizing hormone were determined in 25 patients 8 to 19 years old (mean age 13.2 +/- 1.63) with grades 2 and 3 unilateral varicocele. Testicular growth arrest was considered significant when volume loss was greater than 2 ml. in the ipsilateral testis compared to the contralateral side. Baseline serum testosterone, follicle-stimulating hormone and luteinizing hormone as well as post-gonadotropin releasing hormone stimulation were determined preoperatively and at 4 to 6 months postoperatively. Data are presented as mean plus or minus standard deviation. Results showed an increase in serum testosterone in Tanner's stages 1 (p < 0.028) and 2 to 3 (p < 0.008). No differences were recorded in basal luteinizing hormone and follicle-stimulating hormone, as well as maximal follicle-stimulating hormone levels before and after surgery. A decrease of maximal luteinizing hormone response to gonadotropin releasing hormone test was noted postoperatively in pubertal stages 4 to 5, when compared to preoperative values. Postoperative ipsilateral testicular volume increased in all Tanner stages (p < 0.045, p < 0.008 and p < 0.012, respectively). Our observations suggest that varicocele may be initially responsible for interstitial dysfunction with preservation of germinal function and unilateral testicular growth arrest, however reversible, after pubertal surgical correction. This study supports previous reports suggesting that varicocelectomy in children who show anatomic and functional changes is advisable.

Biochemical markers of acromegalic activity.

Against a clinical score we compared the effectiveness of three biochemical markers of acromegalic activity: a) growth hormone response to i.v. thyrotropin-releasing hormone, b) growth hormone suppression one hour after an oral glucose load, c) basal plasma IGF-I levels. In 21 patients we obtained 39 observations comprising the four parameters. According to the clinical score, patients were divided into three groups: group I = patients before surgery; group II = improved but still clinically active; group III = clinically inactive. After i.v. thyrotropin-releasing hormone, abnormal observations increased although the patients improved clinically, so that this test was excluded from statistical analysis. Abnormalities in plasma IGF-I levels and in GH suppression after oral glucose were similarly frequent in the groups studied: both 100% in group I, both 71.4% in group II, 27.3% vs. 18.2% in group III (p > 0.05). Both tests made exactly the same contribution to the other's capacity to detect acromegalic activity: 3 out of 39 observations (5.1%). We conclude that basal plasma IGF-I is the single best biochemical marker to detect acromegalic activity, since it is statistically at least as useful as growth hormone suppression, and is far more simple for the patient and the laboratory.

Biochemical markers of acromegalic activity.

Against a clinical score we compared the effectiveness of three biochemical markers of acromegalic activity: a) growth hormone response to i.v. thyrotropin-releasing hormone, b) growth hormone suppression one hour after an oral glucose load, c) basal plasma IGF-I levels. In 21 patients we obtained 39 observations comprising the four parameters. According to the clinical score, patients were divided into three groups: group I = patients before surgery; group II = improved but still clinically active; group III = clinically inactive. After i.v. thyrotropin-releasing hormone, abnormal observations increased although the patients improved clinically, so that this test was excluded from statistical analysis. Abnormalities in plasma IGF-I levels and in GH suppression after oral glucose were similarly frequent in the groups studied: both 100

in group I, both 71.4

in group II, 27.3

vs. 18.2

in group III (p > 0.05). Both tests made exactly the same contribution to the others capacity to detect acromegalic activity: 3 out of 39 observations (5.1

). We conclude that basal plasma IGF-I is the single best biochemical marker to detect acromegalic activity, since it is statistically at least as useful as growth hormone suppression, and is far more simple for the patient and the laboratory.