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Background. Immunoassays have been criticized for poor accuracy at low testosterone concentrations. Mass spectrometry (MS) has been proposed as the only reliable method for testosterone determination. The aim of this study was to compare a sensitive testosterone radioimmunoassay (RIA) with results from different MS. Methods. We compared testosterone concentrations determined by a sensitive testosterone RIA, lower limit of detection 0.03 nmol/L and limit of quantitation 0.1 nmol/L, with four tandem MS that were included in an international external quality assessment program for laboratory medicine. We also compared the morning concentrations of testosterone in girls and boys at different pubertal stages, using results from the RIA, with reported values determined by LC-MS/MS, developed for androgen determination in children. Results. The mean (SD), concentrations were similar between RIA and MS: 1.5 (0.3) and 1.4 (0.4) in the child/women range (0.8-2.6 nmol/L) and 16.0 (3.7) and 17.8 (4.5) nmol/L for the adult male range (10.1-30.0 nmol/L), respectively. The ratio between RIA and MS versus results from mean values of the four MS methods was 1.0 (0.18); 1.1 (0.18) for child/women concentrations and 0.9 (0.13) for male testosterone concentrations. Furthermore, compared to the pediatric reference values determined by LC-MS/MS, the sensitive testosterone RIA delivered similar testosterone values across the different pubertal stages. Conclusions. The comparison between different tandem MS methods and a sensitive testosterone RIA illustrates that there are immunoassays that deliver clinically useful information in prepubertal and pubertal children. [ABSTRACT FROM AUTHOR]

Objective: The aim of this work was to investigate the prevalence of premature thelarche (PT) in 18-month-old girls, and the incidence of clinically evaluated PT for girls aged 18–36 months. Methods: In the prevalence substudy, a prospective population-based cohort of 3,140 girls born at Northern Älvsborg county hospital (NÄL) in Trollhättan, Sweden, was followed for 2 years. Girls with breast development at the 18-month health check were referred to one pediatric center in NÄL for evaluation. All girls with PT were included and followed for clinical outcome and 17β-estradiol. The prospective incidence substudy covered 8 years in a 10-year period and included all girls aged 18–36 months born at NÄL who were clinically evaluated for PT. Results: The prevalence of PT at 18 months in our cohort was 1.6/1,000. The 5 girls with PT no longer showed symptoms at the follow-up 3–6 months later. The incidence was 1.1/1,000 for girls aged 18–36 months and 1.0/1,000 for girls aged 18–30 months who were clinically evaluated for their PT. Conclusion: This is the first prospective population-based study of PT and it shows a prevalence of PT at age 18 months of 1.6/1,000. The incidence of clinically evaluated PT was 1.1/1,000. Our result is in line with other studies reporting the incidence of PT from medical records (0.4–40/1,000). The outcome of PT in our study, as in the other studies, is that the great majority of girls show only benign symptoms. [ABSTRACT FROM AUTHOR]

Background: Early onset of breast development in a young girl is usually a benign and isolated prepubertal condition, i.e., premature thelarche (PT), but can sometimes be progressive and the first sign of pubertal precocity (PP). Serum 17β-estradiol (17β-E2) level is a possible marker to differentiate between benign and pathological forms of breast development. We defined an upper serum 17β-E2 level for benign, “classic” PT for girls aged 9–48 months. Methods: Serum 17β-E2 was analysed with a highly sensitive extraction radioimmunoassay (RIA). Gonadotropins, Tanner breast stage, growth, other investigations, and clinical outcome were assessed in 125 girls with breast development, in a population-based study in West Sweden. Results: A total of 125 of 128 girls had a benign form of breast development with a mean serum 17β-E2 level of 15.2 pmol/L and a mean + 2 SD of 31 pmol/L, which was regarded as the upper limit for benign PT; 3 girls with PP had 17β-E2 levels above 70 pmol/L. Conclusion: This is the first study to define an upper serum 17β-E2 level associated with benign PT. Girls aged 9–48 months with PT and Tanner breast stage 2 have 17β-E2 levels below 32 pmol/L using extraction RIA. LH below the detection limit (0.1 IU/L) and measurable FSH support benign PT. [ABSTRACT FROM AUTHOR]

Aims: We studied whether first morning voided (FMV) urinary gonadotropin measurements could be used as a noninvasive alternative to the GnRH test in the assessment of the hypothalamic-pituitary-gonadal function in children. Methods: In a single-center study, we compared FMV urinary gonadotropin concentrations with basal and GnRH-stimulated serum gonadotropin levels in 274 children and adolescents (78 girls, 196 boys) aged 5-17 years referred for growth and pubertal disorders. The concordance between FMV urinary gonadotropin concentrations and GnRH test results was assessed. Results: FMV urinary LH (U-LH), urinary FSH (U-FSH) and their ratios correlated well with the corresponding basal and GnRH-stimulated serum parameters (r = 0.66, p < 0.001). Receiver operating characteristic curve analyses using urinary and serum LH and FSH concentrations showed that FMV U-LH and U-LH/U-FSH performed equally well as the GnRH test in the differentiation of early puberty (Tanner stage 2) from prepuberty (Tanner stage 1) (area under the curve 0.768-0.890 vs. 0.712-0.858). FMV U-LH and U-LH/UFSH performed equally well as basal serum LH in predicting a pubertal GnRH test result (area under the curve 0.90-0.93). Conclusion: FMV U-LH determination can be used for the evaluation of pubertal development and its disorders, reducing the need for invasive GnRH stimulation tests. [ABSTRACT FROM AUTHOR]