Ali Abbara1, Pei Chia Eng1, Maria Phylactou1, Sophie A Clarke1, Edouard Mills1, Germaine Chia1, Lisa Yang1, Chioma Izzi-Engbeaya1, Neil Smith2, Channa N Jayasena1, Alexander N Comninos1, Ravinder Anand-Ivell3, Jesse Rademaker4,5, Cheng Xu4,5, Richard Quinton6,7, Nelly Pitteloud4,5, Waljit S Dhillo8. 1. Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom. 2. Kallmann Syndrome Patient Support Group, London, United Kingdom. 3. School of Biosciences, University of Nottingham, Nottingham, United Kingdom. 4. Service of Endocrinology, Diabetology & Metabolism, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland. 5. Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. 6. Translational & Clinical Research Institute, University of Newcastle-upon-Tyne, Newcastle, United Kingdom. 7. The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, United Kingdom. 8. Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom, w.dhillo@imperial.ac.uk.
Abstract
BACKGROUND: Hypogonadotropic hypogonadism (HH) is hypogonadism due to either hypothalamic or pituitary dysfunction. While gonadotropin-releasing hormone (GnRH) can directly test pituitary function, no specific test of hypothalamic function exists. Kisspeptin-54 (KP54) is a neuropeptide that directly stimulates hypothalamic GnRH release and thus could be used to specifically interrogate hypothalamic function. Congenital HH (CHH) is typically due to variants in genes that control hypothalamic GnRH neuronal migration or function. Thus, we investigated whether KP54 could accurately identify hypothalamic dysfunction in men with CHH. METHODS: Men with CHH (n = 21) and healthy eugonadal men (n = 21) received an intravenous bolus of either GnRH (100 μg) or KP54 (6.4 nmol/kg), on 2 occasions, and were monitored for 6 h after administration of each neuropeptide. RESULTS: Maximal luteinizing hormone (LH) rise after KP54 was significantly greater in healthy men (12.5 iU/L) than in men with CHH (0.4 iU/L; p < 0.0001). KP54 more accurately differentiated CHH men from healthy men than GnRH (area under receiver operating characteristic curve KP54: 1.0, 95% CI 1.0-1.0; GnRH: 0.88, 95% CI 0.76-0.99). Indeed, all CHH men had an LH rise <2.0 iU/L following KP54, whereas all healthy men had an LH rise >4.0 iU/L. Anosmic men with CHH (i.e., Kallmann syndrome) had even lower LH rises after KP54 than did normosmic men with CHH (p = 0.017). Likewise, men identified to have pathogenic/likely pathogenic variants in CHH genes had even lower LH rises after KP54 than other men with CHH (p = 0.035). CONCLUSION: KP54 fully discriminated men with CHH from healthy men. Thus, KP54 could be used to specifically interrogate hypothalamic GnRH neuronal function in patients with CHH.
BACKGROUND: Hypogonadotropic hypogonadism (HH) is hypogonadism due to either hypothalamic or pituitary dysfunction. While gonadotropin-releasing hormone (GnRH) can directly test pituitary function, no specific test of hypothalamic function exists. Kisspeptin-54 (KP54) is a neuropeptide that directly stimulates hypothalamic GnRH release and thus could be used to specifically interrogate hypothalamic function. Congenital HH (CHH) is typically due to variants in genes that control hypothalamic GnRH neuronal migration or function. Thus, we investigated whether KP54 could accurately identify hypothalamic dysfunction in men with CHH. METHODS: Men with CHH (n = 21) and healthy eugonadal men (n = 21) received an intravenous bolus of either GnRH (100 μg) or KP54 (6.4 nmol/kg), on 2 occasions, and were monitored for 6 h after administration of each neuropeptide. RESULTS: Maximal luteinizing hormone (LH) rise after KP54 was significantly greater in healthy men (12.5 iU/L) than in men with CHH (0.4 iU/L; p < 0.0001). KP54 more accurately differentiated CHH men from healthy men than GnRH (area under receiver operating characteristic curve KP54: 1.0, 95% CI 1.0-1.0; GnRH: 0.88, 95% CI 0.76-0.99). Indeed, all CHH men had an LH rise <2.0 iU/L following KP54, whereas all healthy men had an LH rise >4.0 iU/L. Anosmic men with CHH (i.e., Kallmann syndrome) had even lower LH rises after KP54 than did normosmic men with CHH (p = 0.017). Likewise, men identified to have pathogenic/likely pathogenic variants in CHH genes had even lower LH rises after KP54 than other men with CHH (p = 0.035). CONCLUSION: KP54 fully discriminated men with CHH from healthy men. Thus, KP54 could be used to specifically interrogate hypothalamic GnRH neuronal function in patients with CHH.