Learn
Get to know your lab report
Explore a topic, understand the report, or look up a test.
Explore the library
Guides and test explainers, together by topic.
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.
Fasting Glucose
Reported in mg/dL · mmol/L.
TSH, free T4 and free T3: why the first number isn't a thyroid hormone
TSH 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.
Total Cholesterol
Reported in mg/dL · mmol/L.
Vitamin B12 and Active B12: two different tests with similar names
A 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.
Hemoglobin
Reported in g/dL · g/L.
Explore moreShow fewer
Ferritin, serum iron, TIBC and transferrin saturation: four views of iron
An iron panel measures iron in circulation, iron in storage, and the capacity to carry it — plus a percentage computed from two of them.
SGPT (ALT)
Reported in U/L.
Creatinine, eGFR and urea: one measured, the others worked out from it
A 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.
C-Reactive Protein
Reported in mg/dL · mg/L.
What a urinalysis reports, and why several rows share names with blood tests
Three 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.
Lactate Dehydrogenase
Reported in U/L.
Why 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.
Postprandial Glucose
Reported in mg/dL · mmol/L.
TSH
Reported in µIU/mL.
HDL Cholesterol
Reported in mg/dL · mmol/L.
Vitamin D (25-OH)
Reported in ng/mL · nmol/L.
RBC Count
Reported in million/µL.
Ferritin
Reported in ng/mL.
SGOT (AST)
Reported in U/L.
Sodium, potassium, chloride — and the minerals reported beside them
Electrolytes 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.
CRP and hs-CRP: two tests for one protein, used for different things
C-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.
Urine Color
Urine test · what the test measures.
Hemoglobin A
Reported in %.
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.
HbA1c
Reported in % · mmol/mol.
Total T3
Reported in ng/dL · nmol/L.
LDL Cholesterol
Reported in mg/dL · mmol/L.
Vitamin B12
Reported in pg/mL · pmol/L.
WBC Count
Reported in /µL · thousand/µL.
Iron
Reported in µg/dL · µmol/L.
Alkaline Phosphatase
Reported in U/L.
Creatinine
Reported in mg/dL · µmol/L.
Urine Appearance
Urine test · what the test measures.
Hemoglobin A2
Reported in %.
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.
Estimated Average Glucose
Reported in mg/dL.
Total T4
Reported in µg/dL · nmol/L.
VLDL Cholesterol
Reported in mg/dL · mmol/L.
Active B12
Reported in pmol/L.
Platelet Count
Reported in /µL · thousand/µL.
Total Iron Binding Capacity
Reported in µg/dL.
Total Bilirubin
Reported in mg/dL · µmol/L.
Urea
Reported in mg/dL · mmol/L.
Urine pH
Urine test · what the test measures.
Hemoglobin F
Reported in %.
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.
HbA1c and fasting glucose: a three-month average and a single moment
One 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.
Free T3
Reported in pg/mL · pmol/L.
Triglycerides
Reported in mg/dL · mmol/L.
Hematocrit
Reported in %.
UIBC
Reported in µg/dL.
Direct Bilirubin
Reported in mg/dL · µmol/L.
BUN
Reported in mg/dL · mmol/L.
Urine Specific Gravity
Urine test · what the test measures.
ALT, AST, ALP and GGT: four enzymes on one panel
A 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.
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.
Free T4
Reported in ng/dL · pmol/L.
Non-HDL Cholesterol
Reported in mg/dL · mmol/L.
MCV
Reported in fL.
Transferrin
Reported in mg/dL.
Indirect Bilirubin
Reported in mg/dL.
Uric Acid
Reported in mg/dL · µmol/L.
Urine Protein
Urine test · what the test measures.
TC/HDL Ratio
Reported in ratio.
MCH
Reported in pg.
Transferrin Saturation
Reported in %.
Total Protein
Reported in g/dL.
eGFR
Reported in mL/min/1.73m².
Urine Glucose
Urine test · what the test measures.
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.
LDL/HDL Ratio
Reported in ratio.
MCHC
Reported in g/dL.
Albumin
Reported in g/dL.
BUN/Creatinine Ratio
Reported in ratio.
Urine Ketones
Urine test · what the test measures.
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.
LDL vs HDL vs triglycerides: what a lipid panel actually measures
The four numbers on every lipid panel, what each one is, and why the ratios printed at the bottom exist.
RDW
Reported in %.
GGT
Reported in U/L.
Sodium
Reported in mEq/L.
Urine Blood
Urine test · what the test measures.
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.
Neutrophils %
Reported in %.
Globulin
Reported in g/dL.
Potassium
Reported in mEq/L.
Urine Bilirubin
Urine test · what the test measures.
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.
Lymphocytes %
Reported in %.
A/G Ratio
Reported in ratio.
Chloride
Reported in mEq/L.
Urine Urobilinogen
Urine test · what the test measures.
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.
Eosinophils %
Reported in %.
Total protein, albumin, globulin and the A/G ratio: one measurement, three derived rows
Of the four protein rows on a routine panel, two are usually measured and two are worked out from them. Which is which.
Calcium
Reported in mg/dL.
Urine Nitrite
Urine test · what the test measures.
Monocytes %
Reported in %.
Total, direct and indirect bilirubin — and why the third is subtraction
Two of these three rows are measured and one is the difference between them. What bilirubin is, and why the split is reported at all.
Magnesium
Reported in mg/dL.
Urine Leukocyte Esterase
Urine test · what the test measures.
Basophils %
Reported in %.
Phosphorus
Reported in mg/dL.
Urine Pus Cells (WBC)
Reported in /HPF.
MPV
Reported in fL.
Urine RBC
Reported in /HPF.
Absolute Neutrophil Count
Reported in thousand/µL.
Urine Epithelial Cells
Reported in /HPF.
Absolute Lymphocyte Count
Reported in thousand/µL.
Urine Casts
Reported in /LPF.
Absolute Monocyte Count
Reported in thousand/µL.
Urine Crystals
Reported in /HPF.
Absolute Eosinophil Count
Reported in thousand/µL.
Absolute Basophil Count
Reported in thousand/µL.
Haemoglobin, haematocrit and the red cell indices: MCV, MCH, MCHC, RDW
A 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.
The differential: why white cells are printed as both a percentage and a count
Five 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.