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Being Normal: Understanding the Bio-Passport

October 25, 2013

As mentioned previously in “You’re 1 in 1,000 Baby: Understanding the Bio-Passport OFF-Score”, there are a range of OFF-scores that are defined by the WADA BioPassport guidelines that describe the upper and lower values of OFF that are considered “normal”, or more precisely, the range of values that describes 99.9% of the variations in the normal population.  The OFF-score equation and this “normal range” implicitly states that there is a causal relationship between a persons percentage of Reticulocytes (%R) and their amount of Hemoglobin (Hg), in plain language it says “for a given Hg value there is a normal range of %R that would be expected”.

A Normal Probability Space
Figure 1 is a “Probability Space”, it shows a band of %R that are expected to produce a given level of Hg, as defined by the upper and lower bounds of the OFF-score from 85 to 100.  In other words, the area shaded in pink corresponds to the combination of Hg-R% that fall within that 99.9% of the population range, and therefore do NOT produce suspicious OFF scores, or are considered “normal”.  The trend in this “Probability Space” is that it gets wider, and inclines upward as Hg increases.  This trend says that if you have a high Hg, you are likely to have a higher R%, but that other factors can produce higher Hg scores.  Normal range of Hg for adult males is said to be in the range of 14/18 g/dL, however, stbiop_hg-R_rangesudies of athletes and non-athletes places the largest portion of the population in the range of 14.5-16.5 (ref).

One thing that would be important to keep in mind is that t while this may be a good description of the “probability space” of the population of humans as a whole, it might not be necessarily inferred that this also would be the same shape of space that should occur for a given individual.  In other words, an individuals variations might hover about a certain median value for Hg, and their %R values may also have a certain distribution relative to that level of Hg.

Disclaimer: I am not a physician, hematologist, anti-doping expert, or even a veterinarian.  I am just a coach and athlete who has a passion for data analysis, visualization and clean and fair sporting.


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