It could have to do with the albumin and igg levels. Even if they're both with in the normal if the ratio is off then it could mean infection. Sort of like how you can have an increased risk of a heart attack even if your cholesterol levels are all within the 'healthy' mark. If your ratio of good to 'bad' cholesterol is off, is too far tipped towards bad, it's just as bad as if you had high cholesterol.