Blood donation and Metrodin
Blood transfusion service in UK excludes blood donors who have received fertility treatment with Metrodin because of supposed risk of prion disease.
Human Transmissible Spongiform Encephalopathies (TSEs), also known as prion diseases, encompass a group of rare neurodegenerative diseases. Whereas the majority of cases are sporadic (i.e. occur randomly with no known cause), some of these diseases may be transmitted (for example new variant Creutzfeldt Jakob disease, vCJD). In this case, the infectious agent appears to be a “misfolded” prion protein, which is different from the normally occurring, non-infectious prion protein.
Urinary medicinal products have been utilised for over 50 years in fertility treatments. They are a source of natural human proteins which can be prepared for therapeutic administration by purification processes rather than by synthetic routes. The principle group of products produced in this way is the gonadotrophins. Gonadotrophins are a group of hormones, which are involved in regulating fertility and are present at high concentrations in the urine of post-menopausal women (luteinising hormone (LH) and follicle stimulating hormone (FSH)) or pregnant women (human chorionic gonadotrophin (hCG)). These hormones are used in treatments for infertility to stimulate the production of eggs in women and, less commonly, sperm in men.
The urinary-gonadotrophin products, prepared by several pharmaceutical manufacturers, have a long history of safe use. However, in recent years concerns have been expressed that these products could potentially be a source of transmissible spongiform encephalopathy (TSE) infectivity. Furthermore one product, Metrodin, was withdrawn from the market because the country in which it was produced (Italy) had a case of variant CJD, despite there being no evidence that Metrodin posed any risk whatsoever. Despite this, the Blood Transfusion Service in the UK took the “precautionary” step of excluding women who had received Metrodin for fertility treatment from donating blood products. However, most patients who have received fertility treatment will have received a range of drugs and are unlikely to remember which drug they had been prescribed. It may also be difficult to trace such details from hospital notes of treatments given many years ago. If a patient cannot remember or does not know the drug(s) that were used in her treatment, she is still allowed to donate blood, which is a somewhat illogical situation. The unnecessary worry generated by asking such questions of women donating blood should not be underestimated and the British Fertility Society have taken this up with the Blood Transfusion Service who understand our concerns but have to comply with guidance from the Medicines and Healthcare products Regulatory Agency (MHRA).
It is well known that prion proteins are normally found in human urine but not the abnormally folded form of prion proteins that are associated with CJD. However there is no evidence that prion-related conditions can be transmitted through urine or urine-derived medicinal products. No cases of transmission have ever been reported and it could be expected that transmission from urinary-derived gonadotrophins would have been detected if it had occurred given the fact that, for more than 50 years, millions of women worldwide have been treated. Furthermore the male to female sex ratio of CJD has remained stable. Recent studies using the highly purified urinary gonadotrophins that are currently in use that have been inoculated intra-cerebrally into laboratory mice have also failed to elicit prion disease. The European Society of Human Reproduction and Embryology task-force for transmissible viral diseases has also recently reviewed the subject and has found no convincing evidence that would support the presence of prion infectivity in human urine.
Current evidence therefore suggests that urinary-derived gonadotrophins appear to be safe. There is no current biological and epidemiological evidence that supports the possibility of CJD-transmission through urine-derived gonadotrophins.