Mr. Wang is 5’8″ tall and handsome, but his sexual function is very poor, his penis is difficult to erect and he can’t ejaculate. So he went to the hospital for examination. The doctor’s physical examination revealed that his external genitalia such as penis and testicles were dysplastic and his sense of smell was not completely lost. At the doctor’s suggestion, Mr. Wang had his reproductive endocrine hormone levels tested, and the results revealed that three indicators, including follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T), were below normal. Mr. Wang was puzzled as to why this was the case. Abnormal hypothalamic-pituitary-testicular axis can lead to infertility: Male sexual function and fertility are not only related to the reproductive system, but also closely related to the endocrine system. Androgens (mainly testosterone), the engine of a man’s sexual function and spermatogenesis, are mainly secreted by the testes and are regulated by hormones secreted by the hypothalamus and pituitary gland. The hypothalamus secretes gonadotropin-releasing hormone (GnRH), which promotes pituitary function; the pituitary gland secretes gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which promote testicular function; and the testes secrete testosterone (T). The hypothalamus, pituitary gland and testes, all of which can secrete reproductive endocrine hormones, together form the hypothalamic-pituitary-testicular axis, which regulates the level of androgens (mainly testosterone) in the body through positive and negative feedback and other mechanisms, thereby maintaining normal spermatogenic and sexual functions, and any disorder in any of these links may lead to male Infertility. Other endocrine organs, such as the adrenal glands and thyroid gland, can also cause infertility by altering the function of the hypothalamic-pituitary-testicular axis. These infertility due to abnormal endocrine hormone levels are called endocrine infertility. Therefore, doctors measure reproduction-related endocrine hormones precisely to evaluate the function of the hypothalamic-pituitary-testicular axis and to pinpoint the dysfunction. Wang’s test results showed reduced FSH, LH and T. Combined with his physical examination, external genital hypoplasia and olfactory disturbance were found to be most likely a congenital hypothalamic disorder, Kallmann syndrome (KS), a hypo- or hyposmia with absence or diminished sense of smell. hypogonadotropic hypogonadism. As the old saying goes, the upper beam is the lower beam. The disease is caused by the failure of the hypothalamus to properly secrete gonadotropin-releasing hormone (GnRH), which in turn causes a decrease in follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion by the pituitary gland – the upper beam – and a decrease in testosterone (T) secretion by the testes – the The lower beam is distorted, ultimately leading to a lack of normal sexual function and spermatogenesis in the patient. Therefore, Kalman syndrome (KS) can be treated by correcting the upper beam (GnRH, FSH or LH supplementation) and thus the lower beam (improving testicular function). Other endocrine factors leading to infertility: 1. Acquired factors such as trauma, radiation injury, inflammation, tumors, and systemic diseases can lead to infertility by affecting the function of the hypothalamus and pituitary gland. In this case, the primary disease should be actively treated, and gonadotropins and androgens can be used if necessary. 2.Infertility caused by testicular lesions (primary hypogonadism), the causes include congenital diseases, such as Crohn’s syndrome (47, XXY), cryptorchidism, inguinal hernia, etc., and acquired diseases, such as orchitis, testicular torsion, mumps, radiotherapy, etc., which can cause damage to testicular function. 3. The most common kind of endocrine disease, diabetes, may also be the culprit behind infertility. Studies have shown that about 50% of patients who have had diabetes for 7 years or more have fertility problems. On the one hand, diabetes can affect semen quality through the hypothalamic-pituitary-testicular axis; on the other hand, vascular nerve damage caused by diabetes can cause erectile dysfunction and ejaculatory dysfunction, thus causing infertility. In conclusion, for patients with endocrine infertility, we should measure their reproductive endocrine hormones in addition to examining their semen, and combine physical examination and clinical manifestations to pinpoint the pathogenic site of hypothalamic-pituitary-testicular axis and find the cause. When hereditary diseases are suspected, genetics-related tests such as karyotype analysis of chromosomes should also be done. In cases of infertility due to thyroid disease, adrenal disease, or diabetes mellitus, thyroid and adrenal function tests or tests related to diabetes mellitus should also be performed.