Basal level of luteinizing hormone as a key marker of the idiopathic central hypogonadism in women

Abstract

Background: Central hypogonadism (CH) is a syndrome characterized by low levels of peripheral sex steroid hormones due to the lack of central (hypothalamic-pituitary) regulation of reproductive system. In females, CH clinically manifests by amenorrhea, anovulation, and infertility. The classical diagnostic criteria of CH in the absence of organic disease of hypothalamic-pituitary region (“idiopathic” CH) include low gonadotropin levels; however, their levels within the reference ranges do not exclude CH. Moreover, reference ranges for these parameters are different between laboratories. Thus, currently no clear laboratory diagnostic criteria for female CH are available.Aim: To determine the diagnostic value of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) basal levels for the confirmation of CH diagnosis in women and to identify cutoffs of basal gonadotropins levels, which can be considered as diagnostic criteria for female CH.Materials and methods: This cross-sectional study included 87 women: 49 with confirmed CH, aged 18 to 36 years (median, 24 [Q21; Q29]), and 38 healthy fertile women with regular menstrual cycles aged 21 to 45 years (median, 23 [Q23; Q28]). In all subjects, LH, FSH, estradiol, testosterone, prolactin, and free thyroxin levels were measured by chemiluminiscent immunoassay.Results: LH, FSH, estradiol, and prolactin levels in the CH patients were significantly lower than those in healthy subjects. The ROC analysis showed that LH level ≤ 1.95 ME/l indicated the central genesis of hypogonadism with sensitivity of 81.25% and specificity of 91.89%. Basal FSH level ≤ 5.075 ME/l had a 70.00% sensitivity and 77.14% specificity for CH diagnosis.Conclusion: Basal LH level ≤ 1.95 ME/l measured by chemiluminiscent immunoassay can be considered as an idiopathic CH diagnostic criterion in female with amenorrhea due to the hypoestrogenemia with sensitivity of > 80% and specificity > 90%.