Background: Klinefelter syndrome (KS) is the most common sex chromosome abnormality in men. Men with KS may present to a urologist for a variety of reasons, so it is important to the general urology practice to understand the presentation and outcomes for these patients. We therefore present 95 Klinefelter patients to illustrate these concepts. Methods: We identified Klinefelter (47 XXY) patients seen at least once in clinic between the years 2014 and 2024. Mosaic karyotype patients were excluded. Characteristics such as age at initial visit, reason for visit, hormonal data, and infertility outcomes were gathered via chart review. Results: A total of 95 pure 47 XXY karyotype patients were included. Age at first presentation to the clinic ranged from 7 to 53 years, with an average age of 29 years. Hormone levels of all patients from the initial visit reveal a testosterone range from 11 to 663 ng/dL (average 231 ng/dL), FSH range from 0.3 to 63.3 miu/mL (average 31.5 miu/mL), and LH range from 0.3 to 28 miu/mL (average 15 miu/mL). The most common reason for presentation was infertility. Sixty patients were seen for infertility with an age range from 24 to 53 years (average 33 years). Of these patients, 30 went on to have a testicular sperm extraction (TESE) with the goal of achieving a pregnancy. All TESE operations were carried out concurrently with an IVF cycle, so the tissue used was fresh. Among these patients, sperm was found in 11 tissue samples, 7 achieved pregnancy from the sampled tissue and 5 had additional sperm frozen. Initial laboratory testing of the 30 patients who underwent TESE revealed a testosterone range of 11 to 617 ng/dL (average 209 ng/dL), FSH range of 6.7 to 47.2 miu/mL (average 28 miu/mL), and LH range of 4 to 28 miu/mL (average 15 miu/mL). Counseling on a KS diagnosis was the second most common reason for clinic presentation. A total of 19 patients were seen of which ages ranged from 7 to 30 years (average 17 years), with a testosterone range from 12 to 663 ng/dL (average 326 ng/dL), FSH range from 0.3 to 63.3 miu/mL (average 32 miu/mL), and LH range 0.3 to 24.3 miu/mL (average 13 miu/mL). Other reasons for presentation included small testicles, testicular pain, testosterone management, and varicocele. Conclusions: In conclusion, KS patients may present for a variety of reasons to the urology clinic at a range of ages. These patients’ hormonal labs can vary significantly and contrary to expectation, do not always present with low testosterone. For those seeking fertility treatment, TESE can be a viable option.
