RESUMO
Polycystic ovary syndrome (PCOS) affects 6% to 20% of reproductive age women and is the most frequent cause of anovulatory infertility. Its physiopathology may result in part from hypothalamic alterations in the pulsatile secretion of gonadotropin-releasing hormone (GnRH). The neuropeptide kisspeptin participates in the mechanism through stimulation of the hormone's production. The purpose of this study was to review the articles which compared kisspeptin levels in women with PCOS with those of controls. A systematic review of observational studies was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations. The selected studies encompassed a population of patients with PCOS and controls, whose serum kisspeptin levels were evaluated. The studies were retrieved from the Medline, Cochrane, and Embase databases, and four of them were chosen for the review. In most studies, the serum kisspeptin levels were higher in women with PCOS than in controls notwithstanding the BMI. One of the articles showed that circulating plasma levels of kisspeptin were significantly higher in women with PCOS whose BMI was lower than 25 than in obese and overweight women. Our data suggest a higher concentration of serum kisspeptin in women with PCOS irrespective of their BMI. Further experimental and clinical studies are needed to ascertain the role of kisspeptin in PCOS.
Assuntos
Kisspeptinas/metabolismo , Síndrome do Ovário Policístico/metabolismo , Animais , Feminino , Humanos , Kisspeptinas/sangue , Estudos Observacionais como AssuntoRESUMO
BACKGROUND/AIMS: Kisspeptin (KP) is a key player in the regulation of the release of gonadotropin-releasing hormone (GnRH), which increases the secretion of gonadotropin during puberty to establish reproductive function and regulate the hypothalamic-pituitary-gonadal axis. Premature activation of GnRH secretion leads to idiopathic/central gonadotropin-dependent precocious puberty (CPP). We aimed to compare the blood KP concentrations in girls with CPP and healthy controls. METHODS: A systematic review and meta-analysis was performed. We searched MEDLINE, EMBASE, The Cochrane Library, and SciELO. Random-effects model and standardized mean difference (SMD) were used. Heterogeneity was assessed through I2. Meta-regression considered patient age, KP fraction, and analytical method for KP measurement. RESULTS: The 11 studies included comprised 316 CPP patients and 251 controls. Higher KP levels in the CPP group were found (SMD 1.53; CI 95% = 0.56-2.51). Subgroup analysis revealed association with patient age (p = 0.048), indicating a positive correlation between elevation in KP concentration and age in CPP group. A group of patients with precocious thelarche (PT) from 5 of the included studies comprising 121 patients showed higher levels of KP (1.10; -0.25-2.45: CI 95%) and high heterogeneity (I2 = 91%). The CPP/PT ratio for KP level indicates KP 36% higher on CPP than PT patients. CONCLUSIONS: A consistent difference in KP levels between girls with CPP and controls was identified. While there are important limitations in KP assays which argue against its use as a diagnostic tool, the KP levels in CPP versus control and PT children are consistent with the predicted mechanisms and pathophysiology of CPP.