Everybody is different for sure.....52 does not effect me at all but 56-58 does start to have noticeable sides. I donated Monday. I came in just below the max limit of 19.0 hemoglobin with a 18.9 reading. I have been trying to donate since the end of December but kept getting turned away for high hemoglobin readings ( anywhere from 19.3-20.6). I do feel better. I might even donate another pint next week![]()