【特刊综述】性腺功能低下在克氏综合征中的角色

克氏综合症（47，XXY）（KS）是最常见的性染色体异常，也是男性不育和性腺功能低下的常见原因。大部分KS患者终其一生都不知道自己患有这个疾病，只有25％的患者得到诊断，而在青春期前被诊断的更是少数。除了性腺功能低下和无精子症，大多数KS患者都有一定程度的学习障碍，并且可能有多种精神问题。长期性腺功能低下的影响可能使其难以与额外的x染色体引起的基因剂量效应相辨别。不管是什么原因，KS患者常出现身体成分的改变，包括脂肪增加、肌肉减少和骨矿物质流失，同时发生代谢障碍的风险也增加，例如患2型糖尿病和代谢综合征。这些发现应该引起我们的重视，因为他们不仅仅是简单的化验结果，流行病学调查表明KS患者因不同的疾病住院和死亡的风险均增加。KS患者应该在青春期早期就被给予睾丸激素治疗，尽管目前证据不足，因为至今仍未有随机对照试验的文章发表过。在这篇文章里，我们回顾了近期关于KS患者性腺功能低下症的研究进展和睾丸激素治疗的合理性，希望能为这个常见但往往被忽视的综合征提出我们的最佳建议。

The role of hypogonadism in Klinefelter Syndrome

Klinefelter syndrome （KS） （47, XXY） is the most abundant sex-chromosome disorder, and is a common cause of infertility and hypogonadism in men. Most men with KS go through life without knowing the diagnosis, as only 25% are diagnosed and only a few of these before puberty. Apart from hypogonadism and azoospermia, most men with KS suffer from some degree of learning disability and may have various kinds of psychiatric problems. The effects of long-term hypogonadism may be difficult to discern from the gene dose effect of the extra X-chromosome. Whatever the cause, alterations in body composition, with more fat and less muscle mass and diminished bone mineral mass, as well as increased risk of metabolic consequences, such as type 2 diabetes and the metabolic syndrome are all common in KS. These findings should be a concern as they are not simply laboratory findings; epidemiological studies in KS populations show an increased risk of beth hospitalization and death from various diseases. Testosterone treatment should be offered to KS patients from early puberty, to secure a proper masculine development, nonetheless the evidence is weak or nonexisting, since no randomized controlled trials have ever been published. Here, we will review the current knowledge of hypogonadism in KS and the rationale for testosterone treatment and try to give our best recommendations for surveillance of this rather common, but often ignored, syndrome.