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Names, flags, units and reference ranges — a closer look at what your lab prints.
Explore reading reports
What a "calculated" result means, and which of your numbers are one
Several values on a routine report were never measured — they are arithmetic on other rows. Which ones, how to spot them, and why it matters when they change.
Read the guideWhy your report says "fasting required", and what changes when it isn't
Which tests ask you to fast, for how long, and what eating beforehand does to the numbers — plus why a report often prints whether you fasted.
What the H and L flags on a lab report actually assert
A flag compares your number to the range printed beside it on that page — nothing more. What it does not tell you, and why healthy people collect them.
mg/dL and mmol/L: why the same result is printed two different ways
Two unit systems are in routine use, and a marker's number changes completely between them. How to tell which one you are holding, and why you cannot compare across them by eye.
µ and μ are different characters, and lab software often disagrees about which one it used
Two visually identical characters sit behind the µ in µg/dL. Software treats them as different, which is why a unit can fail to match itself between two reports.
Panels, profiles and packages: what you actually paid for
A panel is a bundle of individual tests sold under one name, and the names are not standardised. How to work out what a package included — and what it left out.
How to read a blood test report: every section, decoded
Patient details, specimen, test names, results, units, reference intervals, flags and footnotes — what each block on the page is for, and which parts belong to you rather than to the lab.
Reference interval, cutoff, and the "optimal" numbers online: three different things
The range beside your result, the target a website quotes, and the threshold that defines a condition are built in different ways and answer different questions.
Rounding, decimal places, and why a value moved by 0.1
Labs report to a fixed number of decimal places, and every measurement carries some variation. A small change between reports is often neither.
Serum, plasma, whole blood, urine: why the specimen line changes the result
The same marker measured in a different specimen is a different measurement, with its own reference interval. What the specimen line on your report is telling you.
Why the same lab printed a different reference range for you this year
Ranges are not fixed constants. The lab can change method, revise its reference group, or apply a range that depends on your age — none of which is an error.
Why the same blood test has different "normal" ranges at different labs
Reference intervals are built from each lab's own population and equipment, which is why two labs can print different ranges for the same sample.