An additional description The concentration of red blood cells, if there is a difference from the original is much like the original, but this time 15 to 12.5 are not unusual from a reference value.
Afterthought If the concentration of red blood cells is different from the original as the original 15, but this time it is not unusual to 12.5 from the reference values.
Footnote The concentration of red blood cells, if there is a difference from the original, as the original 15 but this 12.5 although not unusual from the reference value