Subcutaneous implantable testosterone pellets overcome noncompliance in adolescents with Klinefelter syndrome.

For adolescents with hypogonadism, failure to comply with a testosterone replacement therapy (TRT) regimen can be a barrier to obtaining adequate and consistent serum testosterone (T) levels. We evaluated 4 young men with hypogonadism secondary to Klinefelter syndrome to determine if implantable pellets represented a viable treatment option for such patients. Four patients (aged 14-20 years) had previously received TRT but were not compliant. Patients initially received 4 to 10 subcutaneous T pellets with subsequent doses implanted at 3- to 4-month intervals. In all 4 patients, total and free T levels were improved at follow-up, although fluctuations between levels were inconsistent. All patients reported improvement in their energy and concentration, and parents noted improved stability of mood. The mean baseline total T level of 108.3 ng/dL increased in all patients at the time of second pellet implantation. Average total T levels were 325 to 587 ng/dL over the course of therapy. There was significant variability of serum T levels while patients were on therapy. All patients eventually received an increased number of pellets at some point in their care. Subcutaneous implantation of T pellets is a viable option for TRT in young men with Klinefelter syndrome in whom compliance is an issue. However, the requirement for repeat implantation every 3 months, increased cost of therapy and monitoring, dramatic shifts in serum total and free T concentrations, and seemingly unpredictable response requires close monitoring and careful follow up and suggests this modality of therapy may not be appropriate for a substantial number of hypogonadal patients, but this strategy warrants consideration in noncompliant patients.