RT Journal Article SR Electronic T1 Successful thrombolysis of normotensive pulmonary embolism with life-threatening hypoxia in a young man with Klinefelter syndrome JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e240118 DO 10.1136/bcr-2020-240118 VO 14 IS 2 A1 Nuwan Dhanushka Miththinda Jasenthu Kankanamage A1 James Gome YR 2021 UL http://casereports.bmj.com/content/14/2/e240118.abstract AB Klinefelter syndrome (KS) affects males born with an additional X chromosome giving the genotype 47XXY classically. This syndrome has primary features of infertility and hypogonadism along with other features including a genetically hypercoagulable state. When associated with other risk factors, KS further increases the risk of venous thromboembolism and could result in life-threatening pulmonary embolism (PE). There should be a lower threshold in suspecting PE as a cause of acute respiratory failure in this patient group and thrombolysis should be considered early in normotensive PE with severe hypoxia for best patient outcomes. Furthermore, clinicians should be cautious in managing testosterone therapy in patients with KS and additional thromboembolic risk factors.