Total Protein Unit Converter
Total Protein Unit Converter
Convert serum total protein between g/dL, g/L and mg/dL — and use it the way it is meant to be used, subtracted from albumin to give the globulin and the A:G ratio.
Total Protein converter
Mass ladder onlySerum total protein 7.2 g/dL
Formula and conversion factors
g/dL = g/L ÷ 10
mg/dL = g/dL × 1000
Globulin = total protein − albumin
- × 10
- a decilitre is a tenth of a litre, so 7.2 g/dL is 72 g/L — the only conversion most readers need
- no molar unit
- total protein is a mixture of albumin and hundreds of globulins with no common molecular mass, so no mmol/L or µmol/L figure exists
- globulin
- total protein minus albumin, both measured in the same units on the same sample; it is a derived figure and is not assayed directly
- A:G ratio
- albumin divided by globulin, conventionally 1.2 to 2.2; a ratio below 1 means globulin exceeds albumin and needs explaining
Worked example
Serum total protein 7.2 g/dL
7.2 × 10 = 72 g/L
7.2 × 1,000 = 7,200 mg/dL
With an albumin of 42 g/L: globulin = 72 − 42 = 30 g/L, and the A:G ratio is 42 ÷ 30 = 1.4
Within the adult reference interval of 60–80 g/L
Reference intervals across the units
| g/L | g/dL | mg/dL | |
|---|---|---|---|
| Total protein, adult | 60 – 80 | 6.0 – 8.0 | 6,000 – 8,000 |
| Albumin, adult | 35 – 50 | 3.5 – 5.0 | 3,500 – 5,000 |
| Globulin, derived by subtraction | 20 – 35 | 2.0 – 3.5 | 2,000 – 3,500 |
Reading the total against the albumin
| Total protein | Albumin | What it suggests |
|---|---|---|
| Low | Low | Reduced synthesis or loss — chronic liver disease, nephrotic syndrome, protein-losing enteropathy, malnutrition |
| Low | Normal | A low globulin fraction — consider immunodeficiency, particularly if immunoglobulins are unmeasured |
| Normal | Low | A raised globulin offsetting a fallen albumin. A paraprotein can hide here; the total is falsely reassuring |
| High | Low | A markedly raised globulin fraction — myeloma, chronic infection or chronic inflammation until proved otherwise |
| High | Normal or high | Usually haemoconcentration from dehydration or a prolonged tourniquet; repeat before investigating |
Only useful as one half of a pair
Serum total protein is reported in g/L in most of the world and in g/dL in the United States, a factor of ten apart, with mg/dL occasionally seen. A total protein of 7.2 g/dL is 72 g/L and 7,200 mg/dL. There is no molar unit and there cannot be one: the result is the summed mass of albumin and several hundred different globulins, which share no common molecular weight, so mmol/L has no meaning here.
On its own the number says very little. Its real function is arithmetic: subtract the albumin, measured on the same sample and in the same units, and what remains is the globulin fraction. Dividing albumin by globulin gives the albumin-to-globulin ratio, conventionally between about 1.2 and 2.2. Globulin is never assayed directly on a routine panel, so this subtraction is the only way it appears, and it is the quantity that carries the clinical signal.
That pairing is what makes the pattern readable. A low total with a low albumin points to reduced synthesis or protein loss — chronic liver disease, nephrotic syndrome, protein-losing enteropathy, malnutrition. A high total with a low albumin means the globulin fraction has risen substantially, and myeloma, chronic infection and chronic inflammation head that list. A low globulin with a normal albumin raises immunodeficiency. Most importantly, a normal total protein does not exclude a paraprotein: a rising globulin can be offset almost exactly by a falling albumin, leaving the total sitting mid-interval while the A:G ratio has inverted.
Two practical points on the sample. Prolonged tourniquet time and standing upright both raise total protein by several per cent through haemoconcentration, so a marginally high result on a difficult venepuncture is worth repeating before it is investigated. And where the globulin fraction is genuinely raised, or the A:G ratio has inverted, the next tests are serum protein electrophoresis with immunofixation and serum free light chains — not a repeat total protein.
Frequently asked questions
How do I convert total protein from g/dL to g/L?
Multiply by ten, because a decilitre is a tenth of a litre. A total protein of 7.2 g/dL is 72 g/L, or 7,200 mg/dL. Going the other way, divide the g/L figure by ten.
Why is there no molar unit for total protein?
Because it is not one molecule. The result is the summed mass of albumin and several hundred different globulins, which have no common molecular weight, so there is nothing to divide by and no mmol/L or µmol/L figure exists.
How do I work out the globulin?
Subtract the albumin from the total protein, using the same units and the same sample. A total of 72 g/L with an albumin of 42 g/L gives a globulin of 30 g/L and an A:G ratio of 1.4. Globulin is not measured directly on a routine panel.
Can a normal total protein hide a paraprotein?
Yes, and this is the main trap. A rising globulin fraction can be offset almost exactly by a falling albumin, leaving the total sitting mid-interval while the A:G ratio has inverted. Always read the total against the albumin rather than alone.
Can the sample itself raise the total protein?
Yes. Prolonged tourniquet time and upright posture both cause haemoconcentration and can raise total protein by several per cent. A marginally high result after a difficult venepuncture is worth repeating before being investigated.
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References
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018.
- O’Connell TX, Horita TJ, Kasravi B. Understanding and interpreting serum protein electrophoresis. Am Fam Physician. 2005;71(1):105–112.
- Rajkumar SV, Dimopoulos MA, Palumbo A, et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol. 2014;15(12):e538–e548.