Testosterone Therapy in Men with Klinefelter Syndrome: Analysis of a Global Federated Research Network

The objective of this study was to determine the rates of hypogonadism and prescription of testosterone replacement therapy (TRT) in men with Klinefelter syndrome (KS). We hypothesized that men with KS are under-treated for testosterone deficiency with TRT due to a combination of factors, including a poor understanding of hypogonadism in this population and neurocognitive issues leading to delay in seeking of treatment for hypogonadism.

We queried TriNetX, a large multicenter electronic health record database, to identify all men with a diagnosis of KS (ICD-10-CM Q98.4). Prevalence of testosterone deficiency was determined as defined by testosterone level < 300 ng/dL. The primary outcome of the study was prescription of any of the following forms of TRT on the day of diagnosis or later.

There were in total 5437 men with diagnosis of KS. A total of 1581 men with KS received laboratory measurement of testosterone level, 1113 (70.4%) of whom were hypogonadal. Mean testosterone level in this group was 354 ng/dL [50-658]. Of the 1113 men found to be hypogonadal, only 657 (59.0%) men were given prescription for TRT.

This is the first study to evaluate TRT prescribing habits in men with KS. In this large retrospective study, TRT was underprescribed in men with KS. Further studies are needed to corroborate these findings and to evaluate barriers to receiving care in this population.