Prions and fertility medications

In fertility treatments, we regularly use medications to increase the number of eggs available for fertilization.

In Canada, the main three injectable medications, in alphabetical order, are Gonal F, Menopur, and Puregon. Worldwide these are the three leading products.

Gonal F and Puregon are synthesized in the lab. Menopur, however, is a human urine-derived product.  That means it is a natural hormone, collected and concentrated from the urine of thousands of donors. The sources of Menopur is both its strength, and its potential weakness.

Menopur is a natural source of the hormones that drive egg development. But, along with the hormones come other proteins that cannot be fully extricated from the original samples. The extra proteins are well known to women using the medication, for there can be local skin irritation at the site of the injection as a result.

Redness and swelling are not ideal of course, but, many women (and their doctors) are prepared to put up with the inconvience for what may sometimes be a better pregnancy rate. Better than Gonal F or Puregon? Hard to say; there are many studies comparing medications, and they tend to conflict. Anecdotal evidence suggests that, in select cases, Menopur has a role.

But a recent paper from Dr Neil Cashman and his team suggested that, along with these likely-benign proteins that cause the itchiness and redness, there were also prions.

Prions are very, very small proteins that may not be so benign. They’ve been associated with transimissable spongiform encephalopathies such as Creutzfeldt-Jacob disease and, in cows, BSE. To be clear: no cases of prior disease due to the use of urinary gonadotrophins (like Menopur) have been recognized to date.

Nonetheless, it all begs the question: will we continue to use Menopur? As is so often the case in medicine, we’ll need more information before we can be certain. But in the meantime, as they say, “talk to your doctor”. Information in our field is changing all the time.

Tom Hannam

Link to Dr Cashman’s paper: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017815

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