Cystic fibrosis (CF) is a genetic condition that causes thick mucus to build up in organs, which can block or damage their function. CF most commonly affects the lungs but can also cause cysts and scarring to occur in the pancreas, liver, sinuses, intestines, and reproductive organs. Complications of CF can include infections, malnutrition, diabetes, bone weakness, and reproductive health issues. Men with CF can struggle with fertility due to the absence of vas deferens, also known as congenital bilateral absence of the vas deferens (CBAVD). The vas deferens are tube-like organs that carry sperm from the testes to the ejaculatory duct. CF may also affect testicular production of testosterone, or hypogonadism, which can be found in up to 45% of men with CF.
Effect on Testosterone
Male hypogonadism occurs when the body does not produce enough testosterone. This can occur during fetal development, before puberty, or into adulthood. Depending on the stage of development, hypogonadism can cause a variety of signs or symptoms. If hypogonadism develops during adulthood, it can cause decreased sex drive (libido), decreased energy, and contribute to depression. Additionally, over time it can cause erectile dysfunction (ED), infertility, or further muscle and bone weakness. Importantly, treating hypogonadism with testosterone replacement therapy (TRT) can impact male fertility which is not always made clear in available resources.
Effect on Male Fertility
Infertility affects nearly 98% of men with CF. The majority of CF infertility cases are due to obstructive azoospermia (a blockage that prevents sperm from being released into semen) from CBAVD. However, just because sperm is not present in ejaculate does not mean that fertility is not an option. By engaging a urologist with experience with epididymal or testicular sperm extraction and female fertility specialists who can help with assisted reproductive technology, most men with CF can still become fathers. It is important to consider testing of both partners for carriers of the CF gene when planning on building a family.
Because young men with CF may also have hypogonadism or low testosterone, it is important to understand that TRT can suppress production of sperm within the testicle. So, for men with low testosterone who desire fertility and paternity, working with a reproductive urologist may be beneficial. Starting exogenous testosterone (TRT) could make obtaining sperm less successful and unintentionally make family planning more difficult. There are treatments that can help improve testosterone levels while preserving sperm production, or sperm may be frozen for future use before initiating TRT.
Conclusion
Infertility is common in men with CF due to CBAVD and hypogonadism-related issues. Men may be able to collect sperm (through a procedure) for use with assisted reproductive technologies, such as in-vitro fertilization, as part of in their reproductive journey. Hypogonadism can often be treated with testosterone replacement therapy but should only be pursued when fertility goals have been achieved. If you are experiencing infertility — especially with known testosterone deficiency — it may be useful to speak with a reproductive urologist.
References:
Brannigan RE, Hermanson L, Kaczmarek J, Kim SK, Kirkby E, Tanrikut C. Updates to male infertility: AUA/ASRM guideline (2024). J Urol. Published online August 15, 2024. doi:10.1097/JU.0000000000004180. https://www.auajournals.org/doi/10.1097/JU.0000000000004180
Fertility in men with CF. Cystic Fibrosis Foundation. (n.d.). https://www.cff.org/managing-cf/fertility-men-cf
Mayo Foundation for Medical Education and Research. (2024, September 20). Male hypogonadism. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/male-hypogonadism/symptoms-causes/syc-20354881
Naz Khan, F., Mason, K., Roe, A. H., & Tangpricha, V. (2021). CF and male health: Sexual and reproductive health, hypogonadism, and fertility. Journal of Clinical & Translational Endocrinology, 27, 100288. https://doi.org/10.1016/j.jcte.2021.100288
What is cystic fibrosis?. Cleveland Clinic. (2024, May 1). https://my.clevelandclinic.org/health/diseases/9358-cystic-fibrosis
Yoon, J. C., Casella, J. L., Litvin, M., & Dobs, A. S. (2019). Male reproductive health in cystic fibrosis. Journal of Cystic Fibrosis, 18. https://doi.org/10.1016/j.jcf.2019.08.007