Total protein is a blood test that measures the combined amount of albumin and globulin in your serum, the liquid portion of blood. The normal range for adults is 6 to 8 g/dL. You’ll usually see this number on routine blood work like a comprehensive metabolic panel rather than as a standalone test.
What Total Protein Actually Measures
Your blood carries hundreds of different proteins, but they fall into two main groups: albumin and globulin. When a lab reports your total protein, it’s adding these two groups together from a sample of serum (blood plasma with the clotting factors removed).
Albumin is the dominant player, making up more than half of all serum protein. A normal albumin level falls between 3.5 and 5.0 g/dL. The remainder of your total protein comes from globulins, a large family that includes antibodies, enzymes, and carrier proteins that shuttle nutrients through your bloodstream.
The total protein number on its own gives a general snapshot of your health. The more useful information comes from breaking it down into its albumin and globulin components and looking at the ratio between them.
What Albumin and Globulin Do
Albumin’s most critical job is keeping fluid inside your blood vessels. It creates what’s called oncotic pressure, a force that prevents water from leaking out of capillaries into surrounding tissues. Albumin is responsible for about 70% of that pressure. It also binds to chloride ions, which increases its ability to hold onto sodium and water, boosting that fluid-retention effect by roughly 50% beyond what protein concentration alone would produce.
Beyond fluid balance, albumin works as a transport vehicle. It carries fatty acids, hormones, bilirubin, vitamins, metals, and medications through the bloodstream, keeping fat-soluble substances dissolved in plasma. Your liver produces all of the albumin in your blood, so albumin levels often reflect how well the liver is functioning.
Globulins are far more varied. The most familiar subtype is immunoglobulins, your antibodies, which are central to fighting infection. Other globulins include transferrin (which carries iron), haptoglobin (which cleans up free hemoglobin), and alpha-1 antitrypsin (which protects lung tissue from inflammatory damage). Some globulins are made by the liver, others by the immune system.
The Albumin-to-Globulin Ratio
Labs often report an A/G ratio alongside total protein. This is simply your albumin level divided by your globulin level. Because albumin normally makes up the larger share, a healthy A/G ratio is slightly above 1. When that ratio shifts, either because albumin drops or globulins rise, it points toward specific categories of problems. A low A/G ratio can signal liver disease, kidney disease that’s allowing protein to spill into urine, or an overproduction of certain globulins. A high A/G ratio is less common and typically less clinically significant on its own.
Normal Ranges by Age
The standard adult reference range is 6 to 8 g/dL, but normal values shift significantly during childhood. Newborns have the lowest levels, between about 4.1 and 6.3 g/dL. By one to six months, the range rises to roughly 4.4 to 6.7 g/dL. Between six months and one year, it climbs to 5.5 to 7.9 g/dL. Children aged one through eighteen fall between 5.7 and 8.0 g/dL, which overlaps closely with adult values.
Keep in mind that reference ranges can vary slightly between labs. Your results will always be printed alongside the specific range that lab uses, so compare your number to that range rather than memorizing a single cutoff.
What High Total Protein Means
A total protein above 8 g/dL doesn’t automatically signal a serious problem. One of the most common causes is simple dehydration. When your body is low on water, the liquid portion of blood becomes more concentrated, making protein levels look artificially high. Once you rehydrate, the number normalizes.
Chronic infections like hepatitis B, hepatitis C, or HIV can raise protein levels because the immune system ramps up production of antibodies. Chronic inflammation from other causes does the same thing. More concerning, elevated total protein can be an early sign of certain bone marrow disorders, including multiple myeloma. In some cases, high blood protein is the first abnormality detected before any other symptoms appear. A condition called monoclonal gammopathy of undetermined significance (MGUS), where bone marrow produces an abnormal protein, is another possible cause.
What Low Total Protein Means
Low total protein, called hypoproteinemia, has a wider range of potential causes. Because the liver produces albumin and many globulins, any significant liver disease can reduce protein output. Kidney disease can cause the opposite problem: the kidneys start leaking protein into the urine rather than keeping it in the bloodstream. Conditions that impair nutrient absorption in the gut, such as celiac disease or inflammatory bowel disease, can limit the raw materials needed to build proteins in the first place. Severe malnutrition and extensive burns are other recognized causes.
The symptoms of low total protein tend to be gradual and nonspecific. You might notice swelling in the ankles, feet, or abdomen as fluid leaks out of blood vessels that no longer have enough albumin to hold it in. Fatigue, frequent infections, brittle or thinning hair, dry or itchy skin, rashes, and in more advanced cases jaundice (yellowing of the skin) can all develop. Many people with mildly low levels feel nothing at all, which is why the test is valuable as an early flag.
How the Test Is Done
Total protein is measured with a simple blood draw from a vein, typically in your arm. The test is almost always part of a larger panel rather than ordered on its own. A comprehensive metabolic panel (CMP) and liver function tests both include total protein. If an abnormal result appears, your provider may order a protein electrophoresis, which separates the globulin fraction into its subtypes to identify exactly which proteins are elevated or reduced.
Whether you need to fast beforehand depends on which panel the test is bundled into. For a CMP, fasting for 8 to 12 hours is sometimes required because the panel also measures blood sugar and other markers that food affects. If your provider orders only a total protein test, fasting is generally not necessary, but it’s worth confirming with the lab or your provider ahead of time. You should also mention any vitamins, supplements, or medications you’re taking, as some can influence results.