Albumin Unit Converter
Albumin Unit Converter
Convert albumin between g/dL, g/L and µmol/L, and see why a low albumin marks the severity of illness rather than nutritional state.
Albumin converter
Mass ⇄ molarSerum albumin 4.1 g/dL
Formula and conversion factors
g/dL = g/L ÷ 10
µmol/L = g/dL × 150.4
- × 10
- a litre is ten decilitres, so 4.1 g/dL is 41 g/L
- 150.376
- derived from the molecular mass of human serum albumin, 66,500 Da; molar reporting is rare and no clinical threshold uses it
- assay method
- bromocresol green reads higher than bromocresol purple, particularly at low albumin and in renal failure, so results are not interchangeable between laboratories
- negative acute-phase reactant
- hepatic synthesis is suppressed by inflammatory cytokines, so albumin falls with illness independently of nutrition
Worked example
Serum albumin 4.1 g/dL
4.1 × 10 = 41.0 g/L
4.1 × 150.4 = 617 µmol/L
Within the adult reference interval of 3.5–5.0 g/dL
Thresholds across the three units
| g/dL | g/L | µmol/L | |
|---|---|---|---|
| Adult reference interval | 3.5 – 5.0 | 35 – 50 | 526 – 752 |
| Child-Pugh, 1 point | > 3.5 | > 35 | > 526 |
| Child-Pugh, 2 points | 2.8 – 3.5 | 28 – 35 | 421 – 526 |
| Child-Pugh, 3 points | < 2.8 | < 28 | < 421 |
Why the assay method matters
| Method | Behaviour | Where the difference shows |
|---|---|---|
| Bromocresol green (BCG) | Also binds other proteins, so reads higher; the overestimate widens at low albumin | Corrected calcium, Child-Pugh, MELD, ALBI |
| Bromocresol purple (BCP) | More specific for albumin, so reads lower — particularly in renal failure | Dialysis populations, nutritional indices |
| Immunochemical | More specific than either dye; used mainly for comparison and standardisation work | Method comparison studies |
What a low albumin actually means
Albumin is reported in g/dL in the United States and in g/L elsewhere, a factor of ten apart, and occasionally in µmol/L, using a factor of 150.4 derived from its molecular mass of 66,500 daltons. Molar reporting is rare and no clinical threshold is expressed in it, so that conversion is offered here mainly for completeness where a research dataset uses it.
The most consequential error in reading an albumin is treating it as a nutritional marker. Albumin is a negative acute-phase reactant: interleukin-6 and other inflammatory cytokines suppress hepatic synthesis, and capillary leak redistributes it out of the vascular space within hours. A low albumin in an acutely unwell patient is therefore a measure of the severity of illness far more often than of protein intake, and feeding will not correct it while the inflammation persists. It also falls with dilution from fluid resuscitation, with urinary loss in nephrotic syndrome, with gut loss in protein-losing enteropathy, and with reduced synthesis in liver failure.
Method matters more than most clinicians realise. Bromocresol green binds proteins other than albumin and reads higher than bromocresol purple, and the discrepancy widens at low albumin concentrations and in renal failure, where the two can differ by several g/L on the same sample. Immunochemical methods are more specific than either dye. Results from different laboratories are consequently not interchangeable, and a serial trend is only meaningful within one method.
That assay difference then propagates. Albumin drives the corrected calcium calculation, so a method change can shift a corrected calcium across the threshold for hypercalcaemia without any change in the patient. It is a variable in MELD, in Child-Pugh, in the ALBI grade, in the Geriatric Nutritional Risk Index, and in the albumin correction of the anion gap. A patient scored on a bromocresol green result and rescored on bromocresol purple can move a Child-Pugh point on the assay alone.
Frequently asked questions
How do I convert albumin from g/dL to g/L?
Multiply by ten. An albumin of 4.1 g/dL is 41 g/L. To go the other way, divide the g/L figure by ten.
Is a low albumin a sign of malnutrition?
Usually not. Albumin is a negative acute-phase reactant, so inflammation suppresses its synthesis and capillary leak redistributes it out of the circulation. In an acutely unwell patient a low albumin measures the severity of illness, and feeding will not correct it while inflammation persists.
Why does the assay method change the result?
Bromocresol green binds proteins other than albumin and reads higher than bromocresol purple, with the gap widening at low albumin and in renal failure. The two methods can differ by several g/L on the same sample, so results are not interchangeable between laboratories.
Which calculations depend on the albumin result?
Corrected calcium, MELD, Child-Pugh, the ALBI grade, the Geriatric Nutritional Risk Index and the albumin correction of the anion gap all use it. An assay difference therefore propagates into every one of them.
Why is albumin rarely reported in µmol/L?
Mass units are the clinical convention and every published threshold uses them. The µmol/L factor of 150.4 comes from a molecular mass of 66,500 Da and is offered mainly for research datasets.
Related calculators
References
- Infusino I, Panteghini M. Serum albumin: accuracy and clinical use. Clin Chim Acta. 2013;419:15–18.
- Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ. 1973;4(5893):643–646.
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018.