Beullens M, Delanghe JR, Bollen M. False-positive detection of recombinant human erythropoietin in urine following strenuous physical exercise. Blood 2006;107:4711-3. How objective, how factual are scientific results? Should the broader, non-scientific world community take scientific evidence as truth, or just one more opinion? Scientists and physicians are trained to read the scientific literature with a slightly jaundiced eye, always asking questions such as “how reliable is the assay, how valid are the inferences claimed by the authors?” etc. But the non-scientific public is not so trained, and relies heavily, if not exclusively, on the expertise of the scientific community to highlight the strengths and the limitations of scientific measurements and evidence in general. This key issue is highlighted in microcosm by the recent study of Beullens et al., who showed that the “gold standard” immunoassay for recombinant erythropoietin, used to detect prohibited rhEpo in the urine of competitive athletes, can occasionally yield stunningly false positive results. The authors studied an endurance athlete who, on close examination, has a subclinical kidney dysfunction characterized by a mild tubular concentrating defect and proteinuria which are apparent only shortly after strenuous physical exercise. Using the exact isoelectric focusing and immunoblotting (I-IEF) technique currently used by international sports testing authorities, they tested two urine samples from this athlete, one donated immediately following a four kilometer run and four 1000 meter sprints, and another donated one hour later.

 The I-IEF pattern from the urine sample obtained immediately following the run detected multiple glycosylated proteins that looked nearly identical to that generated by small quantities of Epoetin-β (Roche), strongly suggesting the presence of this drug in the runner’s blood. This “positive” result was not seen in urine donated as little as one hour after the run. The fact that Epo has a plasma half-life of more than eight hours suggested that the first result was a false positive, perhaps related to the transient post-exercise proteinuria. The authors then retested the “positive” urine samples by a different technique — immunoblotting after protein denaturation and separation and size fractionation by electrophoresis — and found that the protein detected by the “Epo-specific” monoclonal antibody used in both assays was substantially larger than Epoetin-β, and so must be different. Their interpretation, based on the fact that this larger protein was only detected in the sample generated during a period of transient proteinuria, was that this larger protein was a normal serum protein component to which the anti-Epo monoclonal antibody was cross-reacting.

This result, which confirmed similar suggestions raised as possibilities in the clinical chemistry literature, clearly demonstrated many lessons that physicians and scientists know only too well. Every result is only as reliable as the measurement techniques it uses; no “specific” reagent, whether it is monoclonal antibody or an RNAi, is really specific until it is proven to be so; and, most of all, our laboratory preconceptions need to be carefully validated and reconsidered when we translate these into the clinic, let alone the hurly-burly of the non-medical world. Maintaining this strong, continuously self-correcting relationship with the public and its understanding of science is among our highest responsibilities as scientists, physicians, and citizens.

Competing Interests

Dr. Emerson indicated no relevant conflicts of interest.