Cosecretion of glycosylated prolactin and non-glycosylated prolactin from childhood to the end of puberty.

BACKGROUND: Glycosylated prolactin (G-PRL) is considered as the major post-translational modification of prolactin (PRL) showing reduced lactotropic and mitogenic activities compared to non-glycosylated prolactin (NG-PRL). AIM: To evaluate the evolution of G-PRL in normoprolactinemic children and adolescents and to analyze possible variations in glycosylated/total prolactin (T-PRL) ratios. METHODS: T-PRL, G-PRL and NG-PRL were evaluated in 111 healthy female and male children and adolescents (4.1-18 years), classified as group 1 (Tanner I), group 2 (Tanner II-III) and group 3 (Tanner IV-V). G-PRL and NG-PRL were identified by chromatography on concanavalin-A-Sepharose. RESULTS: G-PRL/T-PRL (median-range): females, group 1: 0.59 (0.17-0.77), group 2: 0.56 (0.31-0.78), group 3: 0.60 (0.38-0.79); males, group 1: 0.64 (0.39-0.80), group 2: 0.61 (0.24-0.79), group 3: 0.62 (0.35-0.90); the p value is not significant among the different groups in both genders. G-PRL/T-PRL ratios do not change when comparing low (first quartile) versus high (third quartile) T-PRL levels in the different groups. CONCLUSION: Our study would appear to support cosecretion of G-PRL and NG-PRL from childhood to the end of puberty. Such cosecretion would not be dependent on sex steroid levels. It is important to point out that puberty does not change the proportions of G-PRL and NG-PRL.

Controversies in the evolution of paediatric-adolescent varicocele: clinical, biochemical and histological studies.

OBJECTIVE: To study hormonal and histological parameters of paediatric-adolescent varicocele in order to know certain aspects of its natural history, in an attempt to find prognostic markers of testicular damage. DESIGN AND METHODS: In a prospective cross-sectional study, we evaluated 93 children and adolescents with left unilateral varicocele and 29 healthy males as control group. All of them were classified according to Tanner stage. Scrotal Doppler in both testes and GnRH and human chorionic gonadotrophin (hCG) tests were performed in all subjects. Surgery was performed in 28 patients and homolateral testicular biopsy in 18. RESULTS: Hormonal measurements of patients with varicocele were compared with a control group for each Tanner stage. Testicular biopsy specimens were analysed by light and electron microscopy. We only observed statistical differences in Tanner III patients in basal FSH (median and range) controls=1.70 (1.10-3.70) IU/l vs varicocele=4.20 (1.00-7.50) IU/l, P<0.05 and in Tanner IV patients in LH post-GnRH: controls=11.0 (7.50-15.0) IU/l vs varicocele=18.0 (5.10-29.0) IU/l, P<0.05 and in testosterone post-hCG: controls=9.50 (7.7-10.0) ng/ml vs varicocele=12.0 (6.2-23.0) ng/ml, P<0.01. No correlation was found between the various clinical grades of varicocele and hormonal measurements for each Tanner stage. No statistically significant differences were found between pre- and post-operative hormonal findings, either in basal levels or in maximal responses. On the other hand, no morphological abnormalities were observed by electron microscopy in germ cells, tubular wall and interstice. CONCLUSIONS: There appears to be no reliable biochemical marker in children and adolescents that may predict impaired testicular function. A significant size discrepancy between both testes, testicular pain and a hyperresponse to GnRH stimulation should continue to be, for the time being, the indications for surgery.

Reproducibility and variability of the arginine test in normal adults. Comparison between sexes.

The biochemical diagnosis of growth hormone deficiency in adults (AGHD) remains controversial, mainly as regards stimulation tests and suggested cut-off lines. The insulin tolerance test proved to be the most effective growth hormone (GH) secretagogue in normal males, but a poor intra-individual reproducibility has been reported. Given the safety of the arginine test (AST), we decided to evaluate the incidence of false negatives (non responder normal subjects), its reproducibility and variability. Twenty five healthy non-obese volunteers (16 males, 9 females) with a chronological age range between 19 and 40 years, (mean: 29.8) were evaluated. AST was performed (0.5 g/kg i.v. infusion for 30 min), measuring GH (IRMA) at baseline (B), 30, 60 and 90 minutes, and it was repeated in the same subject 7 to 30 days later; in females both tests were performed in the early follicular phase. Results (median and range) were: 1st test B: 0.61 (0.35-22.60) micrograms/L; maximal response (Mx Resp) 10.00 (0.48-48.80) micrograms/L. 2nd test B: 0.50 (0.38-27.0) micrograms/L; Mx Resp 11.00 (0.50-47.70) micrograms/L. The statistical evaluation (Wilcoxon signed rank test) showed no differences between B vs. B and Mx Resp vs Mx Resp. Separated by sex, males showed: 1st test: B 0.45 (0.35-4.30) micrograms/L; Mx Resp 6.30 (0.48-48.80) micrograms/L. 2nd test B 0.46 (0.38-8.80) micrograms/L; Mx Resp 10.90 (0.50-47.70) micrograms/L, while females showed 1st test: B 5.20 (0.50-22.60) micrograms/L; mx Resp 14.00 (3.50-36.70) micrograms/L. 2nd test B 3.60 (0.75-27.00) micrograms/L; Mx Resp 13.00 (3.70-28.10) micrograms/L. The statistical comparison (Mann Whitney test) showed significant differences between both sexes in basal values of the first and second test (p < 0.001), and in the maximal response of the first test (p < 0.03). The statistical analysis did not show significant differences in delta increases between males and females, neither in the first AST nor in the second one. Considering GH values > or = 3 micrograms/L as a positive response, 4 males exhibited insufficient responses in both tests and other 2 males showed discordant results between tests 1 and 2. All females evaluated produced responses above 3 micrograms/L in both tests. The results of the present study demonstrate that, particularly in men, AST has no clear limit of normality while it shows good intra-individual reproducibility. In conclusion, at present the biochemical diagnosis of AGHD requires a clear and precise standardization which includes all variables that can modify the GH response to the stimulus used.

Reproducibility and variability of the arginine test in normal adults. Comparison between sexes.

The biochemical diagnosis of growth hormone deficiency in adults (AGHD) remains controversial, mainly as regards stimulation tests and suggested cut-off lines. The insulin tolerance test proved to be the most effective growth hormone (GH) secretagogue in normal males, but a poor intra-individual reproducibility has been reported. Given the safety of the arginine test (AST), we decided to evaluate the incidence of false negatives (non responder normal subjects), its reproducibility and variability. Twenty five healthy non-obese volunteers (16 males, 9 females) with a chronological age range between 19 and 40 years, (mean: 29.8) were evaluated. AST was performed (0.5 g/kg i.v. infusion for 30 min), measuring GH (IRMA) at baseline (B), 30, 60 and 90 minutes, and it was repeated in the same subject 7 to 30 days later; in females both tests were performed in the early follicular phase. Results (median and range) were: 1st test B: 0.61 (0.35-22.60) micrograms/L; maximal response (Mx Resp) 10.00 (0.48-48.80) micrograms/L. 2nd test B: 0.50 (0.38-27.0) micrograms/L; Mx Resp 11.00 (0.50-47.70) micrograms/L. The statistical evaluation (Wilcoxon signed rank test) showed no differences between B vs. B and Mx Resp vs Mx Resp. Separated by sex, males showed: 1st test: B 0.45 (0.35-4.30) micrograms/L; Mx Resp 6.30 (0.48-48.80) micrograms/L. 2nd test B 0.46 (0.38-8.80) micrograms/L; Mx Resp 10.90 (0.50-47.70) micrograms/L, while females showed 1st test: B 5.20 (0.50-22.60) micrograms/L; mx Resp 14.00 (3.50-36.70) micrograms/L. 2nd test B 3.60 (0.75-27.00) micrograms/L; Mx Resp 13.00 (3.70-28.10) micrograms/L. The statistical comparison (Mann Whitney test) showed significant differences between both sexes in basal values of the first and second test (p < 0.001), and in the maximal response of the first test (p < 0.03). The statistical analysis did not show significant differences in delta increases between males and females, neither in the first AST nor in the second one. Considering GH values > or = 3 micrograms/L as a positive response, 4 males exhibited insufficient responses in both tests and other 2 males showed discordant results between tests 1 and 2. All females evaluated produced responses above 3 micrograms/L in both tests. The results of the present study demonstrate that, particularly in men, AST has no clear limit of normality while it shows good intra-individual reproducibility. In conclusion, at present the biochemical diagnosis of AGHD requires a clear and precise standardization which includes all variables that can modify the GH response to the stimulus used.