I'm currently researching the values for a Complete Blood Count. Obviously different sources give slightly different values, usually due to rounding, but I found that some values consistently shifted over the years (according to my sources), meaning both the lower and the upper value in-/decreased, but the range is roughly the same.
Now I wonder who exactly decides which values are normal. Who decides that you should have ~12-16% HGB as Woman/~14-18% HGB as Man (as an example)?
If this is a national decision, please add the information specific to Germany (because that is where I am located). If such information is not available or the relevant data can not be freely accessed via the Web, please write who is usually in charge so I can ask them directly.me