Near the top of most reports is a line naming the specimen: serum, plasma, whole blood, urine. It is easy to skip, and it determines what the numbers underneath can be compared with.
What the words mean
MedlinePlus describes what a tube of blood contains: "Your blood is made up of liquid and solids. The liquid part, called plasma, is made of water, salts, and protein... The solid part of your blood contains red blood cells, white blood cells, and platelets."
Whole blood is the sample as drawn, cells and liquid together.
Plasma is the liquid separated from the cells, with something added to the tube to stop it clotting.
Serum is the liquid left after the sample has been allowed to clot — plasma without the clotting proteins consumed in that process.
Urine is a different fluid entirely, and a urine result is never a blood result.
Why the same marker differs between them
Because the fractions are not the same material. A published comparison of the three blood specimen types found significant differences in measured glucose, with EDTA plasma reading higher than whole blood and serum — the same donor, the same moment, three preparations, three numbers.
This is also why the tube colour matters at collection: the additive in the tube determines which preparation the lab ends up with, and a marker drawn into the wrong tube may be rejected rather than reported.
What this means for reading a report
The reference interval printed beside a result belongs to that specimen as well as to that laboratory. A serum potassium and a plasma potassium are not two attempts at one measurement, and neither is a fasting blood glucose and a urine glucose.
The urinalysis case is the one most likely to confuse, because the names collide. A urinalysis prints rows called GLUCOSE, PROTEIN, BILIRUBIN and BLOOD. None of them is the blood test of the same name. A bare "GLUCOSE" on a urine report is not a blood sugar result and does not belong on the same chart.
Why Arkalife keeps them apart
Because a printed test name alone is not enough to identify a marker — the specimen is part of the identity. Where a name is genuinely ambiguous, the result is stored and shown exactly as the lab printed it and simply left unmapped rather than filed against a blood marker it might not be. A row that is displayed but not charted is the correct outcome there, not a gap.