Oxford University Press (OUP), Journal of Clinical Endocrinology and Metabolism, 2020
Abstract Background Serum concentrations of the peptide hormone Insulin-like factor 3 (INSL3) is a candidate marker for improved distinction between constitutional delay of growth and puberty (CDGP) and permanent hypogonadotropic hypogonadism (HH) in boys. Aim To assess the possible diagnostic role of LC-MS/MS-based INSL3 measurements as a marker of imminent puberty by comparison with testosterone (T) and luteinizing hormone (LH) levels in serum longitudinally collected from 18 healthy boys throughout puberty. Results The first increase in serum LH was detected on average 4 months earlier, as compared to the first observed increases in INSL3 and T. When comparing the two testicular hormones only, we found that in 22% (4 of 18) of the boys the first increase in serum INSL3 was observed prior to the first observed increase in T, whereas in 44% (8 of 18) the first increase in T was observed before the first observed increase in INSL3. In the remaining six boys, the two testicular hormones showed the first increase at the same examination Conclusion In some boys with delayed puberty the first indication of testicular maturation may be detectable by observing serum INSL3. Further studies of LC-MS/MS of serum INSL3 in patients with CDGP and HH are warranted.