Understand your lab report
Plain-language guides to what's actually printed on a blood test — what each marker measures, how reference ranges work, and why results differ between labs. Written for patients, checked against public health sources.
Featured · Reading reportsHow to read a blood test report: every section, decodedPatient 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.3 min read · Reviewed Aug 2026
Markers explainedTotal protein, albumin, globulin and the A/G ratio: one measurement, three derived rowsOf the four protein rows on a routine panel, two are usually measured and two are worked out from them. Which is which.2 min readMarkers explainedVitamin B12 and Active B12: two different tests with similar namesA total B12 measures all of it in circulation; Active B12 measures only the fraction available to your cells. They are not interchangeable, and reports rarely say which you had.3 min readMarkers explainedTotal, direct and indirect bilirubin — and why the third is subtractionTwo of these three rows are measured and one is the difference between them. What bilirubin is, and why the split is reported at all.2 min readMarkers explainedCreatinine, eGFR and urea: one measured, the others worked out from itA kidney panel prints a waste product, an estimate derived from it, and a second waste product measured separately. Which is which, and why eGFR can move when creatinine doesn't.3 min readMarkers explainedCRP and hs-CRP: two tests for one protein, used for different thingsC-reactive protein rises with inflammation from any source. The high-sensitivity version measures the same protein at much smaller amounts, and the two are not interchangeable on a report.3 min readMarkers explainedSodium, potassium, chloride — and the minerals reported beside themElectrolytes are minerals carrying an electrical charge, reported as a tight group. Why they are read together rather than one at a time, and what calcium, magnesium and phosphorus are doing on the same page.3 min readMarkers explainedHbA1c and fasting glucose: a three-month average and a single momentOne is a snapshot of the morning you gave blood, the other reflects roughly three months. Why they can disagree, and what the estimated average glucose row is.3 min readMarkers explainedFerritin, serum iron, TIBC and transferrin saturation: four views of ironAn iron panel measures iron in circulation, iron in storage, and the capacity to carry it — plus a percentage computed from two of them.2 min readMarkers explainedALT, AST, ALP and GGT: four enzymes on one panelA liver panel measures enzymes, not liver function directly. What each one is, and why the same enzyme appears under two different names on different reports.2 min readMarkers explainedHaemoglobin, haematocrit and the red cell indices: MCV, MCH, MCHC, RDWA blood count reports the same red cells several ways — a count, a protein, a percentage, and four averages computed from them. What each column is measuring.2 min readMarkers explainedTSH, free T4 and free T3: why the first number isn't a thyroid hormoneTSH is made by the pituitary, not the thyroid, and moves opposite to the hormones it controls. What each row measures, and why free and total are different tests.3 min readMarkers explainedWhat a urinalysis reports, and why several rows share names with blood testsThree examinations printed as one page — appearance, a chemical dipstick, and a look under a microscope. Plus the naming collision that makes a urine row look like a blood result.3 min readMarkers explainedThe differential: why white cells are printed as both a percentage and a countFive types of white blood cell, each reported twice — once as a share of the total and once as an absolute number. Why both columns exist and why they can disagree.2 min readReading reportsWhat a "calculated" result means, and which of your numbers are oneSeveral 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.2 min readReading reportsWhy your report says "fasting required", and what changes when it isn'tWhich 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.2 min readReading reportsWhat the H and L flags on a lab report actually assertA 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.3 min readReading reportsmg/dL and mmol/L: why the same result is printed two different waysTwo 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.2 min readReading reportsµ and μ are different characters, and lab software often disagrees about which one it usedTwo 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.2 min readReading reportsPanels, profiles and packages: what you actually paid forA 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.2 min readReading reportsReference interval, cutoff, and the "optimal" numbers online: three different thingsThe 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.2 min readReading reportsRounding, decimal places, and why a value moved by 0.1Labs report to a fixed number of decimal places, and every measurement carries some variation. A small change between reports is often neither.2 min readReading reportsSerum, plasma, whole blood, urine: why the specimen line changes the resultThe 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.2 min readReading reportsWhy the same lab printed a different reference range for you this yearRanges 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.2 min readMarkers explainedLDL vs HDL vs triglycerides: what a lipid panel actually measuresThe four numbers on every lipid panel, what each one is, and why the ratios printed at the bottom exist.2 min readReading reportsWhy the same blood test has different "normal" ranges at different labsReference intervals are built from each lab's own population and equipment, which is why two labs can print different ranges for the same sample.1 min read
Reading about markers is step one. Tracking yours is step two.
Upload the report you already have — Arkalife extracts the values and links every page to your own trend for that marker.