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Low-dose hCG can prevent sterility in men prescribed testosterone (2019)
The estimated male population in their reproductive years is about 52 million in the United States, with the age of first-time fathers rising, and about 2.5 million of those men are estimated to have low testosterone,
Larry I. Lipshultz, MD, a professor of urology and chief of the division of male reproductive medicine and surgery at Baylor College of Medicine in Houston, said during a presentation.
Intratesticular testosterone — typically 50 to 100 times higher than serum testosterone levels — is a prerequisite for normal sperm production in men; however, exogenous testosterone prescribed to men with hypogonadism suppresses the intratesticular testosterone level, impairing fertility.
“When one introduces exogenous testosterone, whether it is topical or injectable, what we see is [gonadotropin-releasing hormone] is turned off, gonadotropins decrease, and we see a corresponding decrease in testosterone within the testes and an associated turnoff of sperm production,” Lipshultz said. “A lot of what we know about this phenomenon comes from previous
studies in male contraception using testosterone.”
In a study published in 2005 in
The Journal of Clinical Endocrinology & Metabolism, Andrea D. Coviello, MD, a reproductive endocrinologist and practicing clinician and researcher at Boston University School of Medicine, and colleagues
analyzed data from 29 men with normal reproductive physiology randomly assigned to 200 mg testosterone enanthate weekly in combination with saline placebo or 125 IU, 250 IU or 500 IU hCG every other day for 3 weeks. The researchers found that intratesticular testosterone increased linearly with increasing hCG dose, demonstrating that a relatively low dose of hCG maintains intratesticular testosterone within the normal range in healthy men with gonadotropin suppression, Lipshultz said.
“Without any hCG replacement ... there was literally no intratesticular testosterone, and then as hCG was given in a stepwise fashion, once it reached about 500 U, you were back to baseline [level],” Lipshultz said. “Using this data, and realizing that despite very high doses of testosterone, there were high levels of intratesticular testosterone maintained with low-dose hCG, we then asked whether this low-dose maintenance could also protect spermatogenesis during testosterone treatment.”
If the man desires a future pregnancy, the clinician should prescribe hCG concurrent with testosterone therapy, typically at 500 U subcutaneous three times per week or 1,500 U once weekly if the patient wishes only to prevent testicular atrophy. The patient should cycle off of testosterone twice yearly, at a rate of 3,000 U three times per week for 4 weeks, adding 25 mg daily clomiphene therapy during that period, Lipshultz said. However, for men desiring a pregnancy, 3,000 U hCG three times per week should be prescribed in addition to clomiphene therapy. Clinicians should check the patient’s follicle-stimulating hormone (FSH) level and conduct a semen analysis after 4 months for men desiring pregnancy; if the FSH level is not sufficiently elevated, the clinician should discontinue clomiphene and instead introduce FSH concurrent with the hCG, he said.