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Quantitative and qualitative changes in serum luteinizing hormone after injectable testosterone undecanoate treatment
1National Research Institute for Family Planning, Beijing 100081, China. ygu90@hotmail.com
Insights
Testosterone undecanoate (TU) injections suppress immuno-active LH (i-LH) and bioactive LH (b-LH) in men with Klinefelter
Area of Science:
- Endocrinology and Reproductive Medicine
- Hormone Therapy Research
Background:
- Klinefelter syndrome is associated with altered luteinizing hormone (LH) levels.
- Testosterone undecanoate (TU) is used for testosterone replacement therapy.
- Understanding LH response to TU is crucial for managing hormonal imbalances.
Purpose of the Study:
- To investigate the immuno-active LH (i-LH) and bioactive LH (b-LH) response to TU injections.
- To analyze qualitative changes in circulating LH following TU administration.
- To compare LH profiles in TU responders versus non-responders.
Main Methods:
- Eight men with Klinefelter's syndrome received crossover injections of TU (500 mg and 1000 mg).
- Serum i-LH and b-LH levels were measured pre- and post-injection.
- LH-responders and non-responders were compared based on baseline LH, E2, and T/SHBG ratios.
Main Results:
- A parallel suppression of i-LH and b-LH was observed, with high inter-correlation (r = 0.84).
- TU injection decreased serum i-FSH levels at both doses.
- LH-responders exhibited lower baseline i-LH/b-LH, higher E2, and a higher T/SHBG ratio.
Conclusions:
- A 1000 mg loading dose of TU is effective for initial LH suppression.
- Lower TU doses (500 mg) may require repeated injections for sufficient LH suppression.
- Lower baseline i-LH may characterize LH-responders.
Aim:
To clarify the immuno-active LH (i-LH) and bioactive LH (b-LH) responses and qualitative changes in the circulating LH to testosterone undecanoate (TU) injection.
Methods:
Eight men with Klinefelter's syndrome were recruited for the study. They received crossover injections of TU at doses of 500 and 1000 mg. Serum i-LH and b-LH levels before and at various time intervals after TU injection were measured and the serum i-LH, b-LH, b-LH/i-LH (B/I) and testosterone/sex hormone-binding globulin (T/SHBG) ratio in LH-responders and LH non-responders were compared.
Results:
A parallel suppression of serum i-LH and b-LH was consistent with their overall high correlation between each other (r = 0.84, P < 0.001). Mean serum i-FSH levels were decreased by TU injection at both doses without dose-response effects. LH-responders had lower baseline serum i-LH and b-LH, and higher E2 levels and T/SHBG ratio. There was a quantitative change in serum LH as induced by TU without qualitative change within LH-responders os LH-non-responders.
Conclusion:
A high loading dose (1000 mg) of TU is important for the initial suppression of LH. With the lower dose (500 mg), repeated injections will be required to attain such LH suppression for the purpose of fertility regulation. The lower baseline serum i-LH level may be an intrinsic characteristic of LH-responders.
