Protein, total

Also known as TP, serum protein

protein · no single molecular formula

LOINC 2885-2 code verified serum g/dL

What this substance is

The sum of every protein in serum, mostly albumin and the globulins. There is no one molecule, so nothing to draw.

Reference ranges

Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.

This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.

How it is measured

In practice

A health worker takes a small amount of blood from a vein in your arm with a needle. It usually takes less than five minutes. If the test is part of a larger blood panel, you may need to fast for a few hours first.

Venous blood sample drawn from the antecubital vein or back of the hand. Many medicines can interfere with the result; the provider advises whether any should be stopped. Fasting may be needed when total protein is run as part of another panel.

Before the test

Fast for several hours if your provider asks, when the test is part of another blood panel.
Tell your provider about every medicine you take; do not stop any unless told to.

Where: laboratory

Sources: Total Protein and Albumin/Globulin (A/G) Ratio, MedlinePlus (U.S. National Library of Medicine); Total protein, MedlinePlus Medical Encyclopedia cited · not yet checked by a person

In the lab

spectrophotometry

Biuret

Proteins are long chains of building blocks. In a special copper liquid, those chains turn purple. The darker the purple, the more protein is in the blood.

Cupric ions react with protein peptide bonds in alkaline solution to form the purple biuret complex, read at 546 nm; colour intensity is proportional to total protein concentration.

Read by: Absorbance at 546 nm

What can throw it off

IgM gammopathy (rare)

Why labs disagree: The assay itself is not usually the main reason ranges differ: in an eight- platform comparison on serum from healthy volunteers, total protein was rated "green", meaning method bias would not prevent labs sharing one reference interval. Ranges can legitimately differ for reasons such as ethnicity and analytical methodology, but a UK study found that labs using the same platform and reagents often printed different reference intervals with no sound basis for the difference.

Sources: Koerbin G et al. Bias Assessment of General Chemistry Analytes using Commutable Samples. Clin Biochem Rev 2014;35:203-211 (PMC4310060); NHANES 2017-2018 Laboratory Procedure Manual, Total Protein, CDC/NCHS cited · not yet checked by a person

What it reports on

liver synthesized by
Albumin, most of the protein in blood, is made in the liver, along with some globulins.
immune system synthesized by
Some globulins, the smaller share of blood protein, are made by the immune system.

Associated symptoms

Conditions this marker features in

Ordered as part of

cmp · hepatic