Human chorionic gonadotropin (HCG) has a name as a weight-loss drug and a use in fertility treatments, but new findings show that it can carry molecules called prions that cause “mad cow” disease in humans. A team of researchers from Canada, France, and the U.S. published their findings linking HCG and prions in late March, 2011, in the online journal PLoS One.
Alain van Dorsselaer and colleagues studied HCG from urine samples and also examined injectable urine-derived hormones used for fertility treatments. They found that these samples contained prions, a kind of rogue protein molecule that causes “mad cow disease,” known in people as Creutzfeldt-Jakob disease. One version of this fatal nerve disorder shows symptoms decades after exposure to a prion source.
Prions are proteins that have gone bad, wadding up instead of folding like they should. But they don’t stop with their own misbehavior. Prions can also tap other proteins and cause them to go bad, too. The result is wads of these rogue proteins. Ultimately, holes form in the brain tissue where they lurk.
These rogue proteins are known for causing diseases like Creutzfeldt-Jakob in people and “mad cow” and scrapie in animals. According to Dorsselaer and the paper co-authors, injecting prions into muscle – as women do with HCG for fertility treatment – is one way to become infected.
HCG is approved for use as a fertility treatment, but some people have touted it as a weight-loss hormone, too. No evidence at all, however, links HCG to weight loss. Its main natural day job is as a pregnancy hormone. In fact, when a woman takes a urine pregnancy test, HCG is the hormone the test detects. In fertility treatments, HCG mimics a hormone that causes ovulation.
Is there an option other than urine-derived HCG for people who need the hormone for fertility treatment? Yes, there is. Recombinant HCG is made using special cells in a laboratory, rather than being extracted directly from urine. Dorsselaer and co-authors checked recombinant HCG for prions. They found no evidence of them.
Should people who are using HCG either for weight loss or for fertility be concerned? Dorsselaer and colleagues indicate as much in their PLoS One paper, commenting that the possibility of prion contamination of urine-derived HCG means the risks of using that hormone source could outweigh the benefits.
Dr. Emily Willingham came to EarthSky from The Biology Files. Her background includes a PhD in biological sciences, a bachelor's degree in English, and a published book: The Complete Idiot's Guide to College Biology. She is a scientist, writer, editor, teacher, autism & ADHD parent, and "all around opinionator." Says Emily: "Got an English BA & biology PhD, & I'm not afraid to use them, often together."