Endocrine Abstracts

Central hypogonadism (CH) is a syndrome that can be revealed in women with hypoestrogenic amenorrhea due to the lack of normal response of gonadotropins to the hypoestrogenemia. CH can be caused by organic lesion of the hypothalamo-pituitary region or has idiopathic character – without any structural background. This syndrome is often called ’hypogonadotropic hypogonadism’, but LH and FSH levels within ’normal’ laboratory range does not exclude CH because insufficiency of impulse secretion can appear despite normal basal secretion.

Patients and methods

46 women with idiopathic CH (18-45 y.o., BMI 16-25 kg/m2), 25 women with CH due to the organic lesions (18-45 y.o., BMI 17-37 kg/m2), 68 healthy cycling women (control group, 19-45 y.o., BMI 17-31 kg/m2). Organic causes of CH were as follows: congenital empty sella turcica and pituitary hypoplasia; pituitary adenomas and craniopharyngiomas presently or earlier (treated by surgery). LH and FSH levels were measured in all participants by chemiluminescent immunoassay; in healthy women tests were performed in early follicular phase.

Results

According to Mann-Whitney test, LH and FSH levels were significantly lower in patients of both groups than in control group (p<0.0001 in all cases). Moreover, LH and FSH were significantly lower in group of organic lesions than in group of idiopathic CH (p=0.0017 for LH and p=0.0014 for FSH). ROC-analysis showed that LH<2.36 ME/l with sensitivity 82.61% and specificity 94.12% and FSH<5.075 ME/l with sensitivity 73.91% and specificity 80.88% pointed to central genesis of hypogonadism without organic lesions. Similar analysis was performed for patients with CH due to the organic lesions: LH<1.8 ME/l with sensitivity 96.0% and specificity 98.53% and FSH<3.145 ME/l with sensitivity 92.0% and specificity 95.59% speaks in favor of CH due to the pituitary organic lesion.

Conclusion

In female patients with hypoestrogenic amenorrhea LH<2.36 ME/l and FSH<5.075 ME/l are pointing to central genesis of hypogonadism with high sensitivity and specificity; LH<1.8 ME/l and FSH<3.145 ME/l in case of those female patients can point to organic cause of central hypogonadism, and thus can be considered as indication for pituitary region MRI if it was not performed earlier.