Decreased neurokinin B as a risk factor of functional hypothalamic amenorrhea.

BACKGROUND: Neurokinin B (NKB) belongs to the tachykinin family of proteins who's regulation is essential for proper function of the reproductive system. It has been shown that patients with functional hypothalamic amenorrhea (FHA) exhibit decreased levels of serum kisspeptin. As kisspeptin secretion is regulated by NKB signaling, it is reasonable to suspect that patients with FHA will also have abnormal NKB secretion. AIM: To assess NKB levels in patients with FHA and to determine whether NKB signaling is affected in these patients. We hypothesized that decreased NKB signaling is a factor contributing to the development of the FHA. MATERIALS AND METHODS: A total of 147 patients with FHA and 88 healthy age-matched controls were enrolled. Baseline blood samples were drawn from both groups to measure serum concentrations of NKB, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), prolactin (PRL), thyroid-stimulating hormone (TSH), free thyroxine (fT4), cortisol, dehydroepiandrosterone sulfate (DHEA-S), testosterone (T), glucose, and insulin. RESULTS: Mean serum NKB levels were found to be decreased significantly in the FHA group when compared with the control group (628.35 ± 324.92 vs. 721.41 ± 337.57 ng/L, respectively p = 0.002). No statistical difference was observed in NKB-1 levels within the FHA group when selecting for normal and decreased body mass index. CONCLUSIONS: Patients with FHA were found to have decreased serum NKB concentrations when compared to healthy controls. Abnormal NKB secretion is likely a key factor contributing to development of FHA.