ISSN: 2167-0250
Anna Illiano, Chiara Melchiorre, Carlo Cioci, Gabriella Pinto, Francesca Di Rella, Alessandro Conforti,Luigi Carbone, Angela Amoresano
Gonadotropins, as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), belong to a family of glycoprotein hormones along with human placental chorionic gonadotropin (hCG), and thyroid-stimulating hormone (TSH). LH and FSH are key regulators of reproduction, and they act in an endocrine manner to regulate steroidogenesis and gametogenesis in the ovary and testis. Nowadays, highly purified and recombinant formulations of the gonadotropins are commonly used in the treatment of hypogonadism and infertility. Therefore, the accurate measurement and characterization of serum gonadotropins is essential to monitor the hormonal response of patient treatment, but their absolute quantification is a great challenge due to their extensive heterogeneity, and their very low concentrations in serum. The reference method to quantify circulating gonadotropins, the enzyme-linked immunosorbent assay (ELISA), is limited by the availability of high-quality antibodies for each biomarker candidate and to the specificity of the antigen-antibody-affinity.
The aim of this study was to set-up a valid alternative to the common immunoassays, based on tandem mass spectrometry in multiple reaction monitoring (MRM) ion mode, to quantify gonadotropins (LH and FSH) and TSH in serum. The developed method allows the identification and quantification of target proteins by monitoring 3 specific prototypic peptides (precursor ion) and 3 to 5 best fragments (product ion) for each hormone, and it was successfully applied to the analysis of sera from a small cohort of women. Results show comparable sensitivity to ELISA assays, with the advantage of being faster and more selective. Furthermore, this method could be easily implemented with other serum protein of interest saving time and cost in routine analysis.