On your lab report, you’ll see a column marked “Reference Range.” These are the minimum and maximum of each bodily substance a person needs to stay healthy. They’re based on decades of statistical and medical research.
Should everyone fall within this range?
Although most reference ranges apply to everyone, the “normal” range for some can vary according to age, gender and ethnicity. Reference ranges can even differ from lab to lab.
Which ranges vary?
Many liver function measurements will vary depending on your race. With kidneys, “for some reason, filtration by African Americans is not as high as in white Americans,” says Chicago-based nurse practitioner Bethsheba Johnson. “So labs use an equation to adjust renal function.”
How can I know what’s “normal” for me?
If you’re seeing a doc for the first time, she should do a “baseline” test to help interpret later results. And to avoid throwing your cholesterol or glucose results out of whack, don’t eat before a blood test (see “Ace Your Tests”).