Lab results explained

What your lab results actually mean

Plain-English explanations of the values that turn up on a blood test — what each one measures, what pushes it up or down, and what a doctor usually does next.

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A PDF or a photo. We read it, ask a few optional questions, and explain what your results mean — for you, not in general.

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Why your lab's "normal" is not the same as ours

Reference ranges differ between laboratories — different equipment, different methods, different populations. That is why a value flagged high at one lab sits inside the range at another, and why the range printed on your own report is the one that counts.

Ranges also depend on who you are. Sex, age, pregnancy, medication and even the time of day move them, and most reports print one range for everybody. Reading a number without knowing any of that is how an entirely ordinary result becomes a fright.

TSH 4.6 mIU/L One sample, one day Lab A · normal 0.4 – 4.0 High Lab B · normal 0.4 – 5.0 Normal