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Researchers evaluated mean hematocrit before and after pellet implantation in a cohort of 97 patients.
A recent study has found that testosterone replacement therapy via pellet implantation appears to be safe in terms of risk for polycythemia.
The study, which examined the incidence and risk factors for development of erythrocytosis in a multi-institutional retrospective database analysis, stems from the debate over the safety of testosterone replacement and researchers’ own practices and experiences.
The study encompassed a retrospective chart review of all patients treated at two tertiary referral centers in the Boston area-Massachusetts General Hospital (MGH) and Lahey Hospital & Medical Center. Men treated with testosterone pellets who also had the full complement of pre-treatment screening tests, in addition to consistent surveillance labs, were included.
Senior author Cigdem (Cori) Tanrikut, MD, of Massachusetts General Hospital Department of Urology, said MGH and Lahey Clinic collectively have a relatively large cohort of patients who receive testosterone replacement therapy (TRT) via testosterone pellets. This initial study focused on the risk of polycythemia while on testosterone pellets as the treatment modality for TRT, as hematocrit is an objective measure and is closely followed during treatment.
“Older data have demonstrated that the mode of testosterone delivery, and the dosing schedule, can impact whether patients’ hematocrit may rise while on treatment,” Dr. Tanrikut told Urology Times. “Well-designed studies involving the Organon product had previously produced reassuring results; however, less was known regarding the currently marketed and used pellets. We sought to characterize this basic safety parameter.”
The data, published in The Journal of Urology (2016; 196:1715-20), demonstrated a statistically significant hematocrit rise of 2.2% when comparing pre-treatment and post-treatment values.
“In our experience, we have found an increase of this magnitude to not be clinically significant, and so we concluded that for our cohort of patients, testosterone pellets are safe in terms of risk for polycythemia,” lead author Russell P. Hayden, MD, of MGH told Urology Times. “We used multiple linear regression of pre-treatment parameters in an effort to identify risk factors for individuals who may experience marked increases of hematocrit. Interestingly, we found an inverse relationship between pre-treatment hematocrit and the relative rise of hematocrit.”
Next: 2.2% increase in mean hemocrit observed
A total of 97 patients were included in the study. The average age of the cohort was 52 years (range, 24 to 80 years). Mean hematocrit before and after pellet implantation was 43.9% and 46.1%, respectively, corresponding to an increase of 2.2%(CI 1.4-2.9, p<.001). The average increase in testosterone was 145.3 ng/dL from an initial mean of 278.9 ng/dL (CI: 105.7-184.9, p<.001).
Linear regression demonstrated that pretreatment hematocrit was inversely related to the expected change in hematocrit, the research showed. Pretreatment comorbidity status (ie, the presence of hypertension, hyperlipidemia, obesity, or diabetes) was not associated with a significant increase in post-treatment hematocrit.
“Although the data demonstrates a statistically significant increase in hematocrit, an increment of 2.2% is unlikely to translate into clinical relevance,” Dr. Hayden said. “Thus, for this cohort of patients, implantable testosterone pellets appear safe in terms of the risk of polycythemia. Pretreatment hematocrit may serve as a predictor of a significant hematocrit increase after the initiation of therapy.”
The study showed that those with lower initial hematocrit tended to have a greater increase when analyzing their post-treatment labs. The implications and pathophysiology of this finding remain unclear.
“Although it was not surprising to detect a statistically significant rise of hematocrit after treatment, the relative increase in this parameter was not consistent across all patients,” Dr. Tanrikut said. “Urology is a field that is characterized by rapid adoption of new technology, including pharmaceuticals, surgical techniques, and devices. It is our duty to our patients that we approach these advances critically with safety and clinical outcomes in mind.”
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