Albumin g/dL to g/L Converter

Albumin in two units: the short answer

To convert serum albumin from g/dL to g/L, multiply by 10. To convert g/L back to g/dL, divide by 10. An albumin of 4.2 g/dL is therefore 42 g/L, and 33 g/L is 3.3 g/dL. Albumin is very occasionally reported in µmol/L (1 g/L ≈ 15.2 µmol/L, based on a molar mass of about 66,500 g/mol), but almost all laboratories use g/dL or g/L. The converter above handles g/dL ↔ g/L and shows the typical adult range.

The conversion is simple, but albumin is used in several formulas – corrected calcium, the albumin-corrected anion gap, liver disease scores and calculated free testosterone – and each formula expects albumin in a specific unit. Entering 42 where 4.2 is expected, or the other way round, can make the output wildly wrong. This guide explains the units, the normal range, what albumin reflects (and what it does not), and how it is used in calculations.

What albumin is

Albumin is the most abundant protein in blood plasma, making up about 50–60% of total plasma protein. It is made exclusively by the liver, at a rate of about 10–15 g per day, and has a half-life of about three weeks. Albumin:

• maintains oncotic pressure – the force that keeps fluid inside blood vessels; low albumin allows fluid to leak into tissues, contributing to swelling (oedema)
• transports many substances, including calcium, bilirubin, fatty acids, thyroid hormones, testosterone and many medicines (such as warfarin, phenytoin and some antibiotics)
• acts as a buffer and antioxidant

Because albumin carries so many substances, its level affects the interpretation of other tests, such as calcium and phenytoin levels.

g/dL and g/L explained

• g/dL (grams per deciliter) – used in the United States and some other countries.
• g/L (grams per liter) – used in the UK, Europe, Australia, Canada and most of the world.

A deciliter is one-tenth of a liter, so the number in g/L is always ten times the number in g/dL.

How to convert albumin step by step

1. Look at the size of the number: values around 3–5 are almost certainly g/dL; values around 30–50 are g/L.
2. g/dL to g/L: multiply by 10.
3. g/L to g/dL: divide by 10.

Worked examples

• 2.5 g/dL = 25 g/L – markedly low.
• 3.0 g/dL = 30 g/L – a commonly used threshold for hypoalbuminaemia in many clinical contexts.
• 3.5 g/dL = 35 g/L – the lower limit of a typical adult range.
• 4.0 g/dL = 40 g/L – the "normal" value used in the corrected calcium formula.
• 5.0 g/dL = 50 g/L – the upper limit of a typical adult range.
• 28 g/L = 2.8 g/dL.
• 44 g/L = 4.4 g/dL.

Albumin conversion chart

Normal albumin range

A typical adult serum albumin range is about 3.5–5.0 g/dL (35–50 g/L). Many UK laboratories use 35–50 g/L; some methods give slightly different ranges, for example 34–54 g/L. The two most common laboratory methods – bromocresol green (BCG) and bromocresol purple (BCP) – can differ by several g/L, especially in people with kidney disease, with BCG tending to read higher. This matters for formulas that use albumin.

Age, pregnancy and posture

• Older adults may have slightly lower albumin, though a markedly low value should not be assumed to be due to age.
• Pregnancy lowers albumin, typically by 5–10 g/L by the third trimester, because of plasma volume expansion.
• Posture matters: albumin is about 10% higher when blood is drawn standing than after lying down, because fluid moves out of the circulation when upright.
• Newborns have slightly lower values than adults.

Low albumin (hypoalbuminaemia)

Low albumin is very common in hospital and has many causes. It is useful to think in four groups:

Reduced production

• Chronic liver disease and cirrhosis – the liver cannot make enough albumin.
• Malnutrition – although albumin is often treated as a nutrition marker, it is a poor one (see below).

Increased loss

• Kidney loss – nephrotic syndrome, in which large amounts of albumin leak into urine, can lower serum albumin dramatically, sometimes below 2.0 g/dL (20 g/L).
• Gut loss – protein-losing enteropathy, for example in inflammatory bowel disease.
• Skin loss – extensive burns.

Redistribution and dilution

• Inflammation and acute illness – albumin is a negative acute-phase protein: during infection, injury, surgery or cancer, the liver reduces albumin production, and capillary leak moves albumin out of the bloodstream. This is the most common reason for low albumin in hospital.
• Fluid overload – heart failure or large volumes of intravenous fluid dilute albumin.

Other

• Pregnancy (dilution) and some inherited conditions (analbuminaemia, very rare).

Why albumin is not a good marker of nutrition

Albumin has long been used as a "nutrition test", but its level falls mainly with inflammation and illness rather than with poor intake. People with anorexia nervosa can have normal albumin despite severe malnutrition, while well-nourished people with acute infection often have low albumin. Current nutrition guidance, including from ASPEN, advises against using albumin alone to diagnose malnutrition. Low albumin is, however, a strong marker of overall illness severity and predicts worse outcomes in many conditions.

High albumin

A high albumin is uncommon and is almost always due to dehydration, which concentrates all plasma proteins. Prolonged tourniquet use can also raise results slightly. Correcting dehydration brings albumin back to normal.

Albumin in calculations

Several commonly used formulas include albumin, and each expects a specific unit:

Corrected calcium

Because about 40% of calcium is bound to albumin, total calcium falls when albumin is low. The common correction is:

• US units: corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin in g/dL)
• SI units: corrected Ca (mmol/L) = measured Ca + 0.02 × (40 − albumin in g/L)

Using g/L in the US formula would give an absurd result. Our corrected calcium calculator accepts either unit.

Albumin-corrected anion gap

Albumin is the main unmeasured anion. For every 1 g/dL (10 g/L) fall in albumin below about 4.0 g/dL (40 g/L), the anion gap falls by about 2.5 mmol/L. The Figge correction is: corrected anion gap = anion gap + 2.5 × (4.0 − albumin in g/dL), or + 0.25 × (40 − albumin in g/L). Without this correction, a high anion gap acidosis can be missed in people with low albumin.

Liver disease scores

The Child–Pugh score awards points for albumin above 3.5 g/dL (35 g/L), 2.8–3.5 g/dL (28–35 g/L), and below 2.8 g/dL (28 g/L). The ALBI grade uses albumin in g/L with bilirubin in µmol/L.

Free testosterone

The Vermeulen equation for calculated free testosterone uses albumin; many laboratories assume 4.3 g/dL (43 g/L) if it is not measured.

Total protein, globulin and the albumin/globulin ratio

Liver panels often report total protein alongside albumin. The difference between them is the globulin fraction – mainly antibodies (immunoglobulins) and other carrier and inflammatory proteins:

• Globulin = total protein − albumin. A typical globulin is about 2.0–3.5 g/dL (20–35 g/L).
• Albumin/globulin (A/G) ratio – usually about 1.1–2.5.

A high globulin, or a low A/G ratio, can reflect chronic inflammation, chronic infection, liver disease or an abnormal production of a single antibody (a paraprotein), as in myeloma. When globulin is unexpectedly high, clinicians may request serum protein electrophoresis. A low globulin can indicate antibody deficiency. These values use the same units as albumin, so converting between g/dL and g/L is again a matter of multiplying or dividing by 10.

Albumin and medicine levels

Many medicines are carried on albumin, and only the unbound (free) fraction is active. When albumin is low, more of the medicine is free, so a standard total blood level may underestimate its effect. The classic example is phenytoin, an anti-seizure medicine. The Sheiner–Tozer equation estimates the corrected phenytoin level: corrected level = measured level ÷ (0.2 × albumin in g/dL + 0.1), with a different coefficient in kidney failure. Again, albumin must be in g/dL for this formula – using g/L would make the corrected value far too low. Many laboratories now measure free phenytoin directly instead.

Albumin in liver and kidney disease

In cirrhosis, a falling albumin reflects declining liver function and is part of the Child–Pugh score. Low albumin also contributes to fluid accumulation in the abdomen (ascites) together with high pressure in the portal vein. Intravenous albumin is given after large-volume drainage of ascites (typically about 8 g of albumin per liter of fluid removed when more than 5 liters are drained) to prevent circulatory problems.

In nephrotic syndrome, heavy protein loss in the urine – more than 3.5 g per day in adults – causes low serum albumin, swelling and high cholesterol, and increases the risk of blood clots and infections. Serum albumin is used to monitor response to treatment; as the kidneys recover, protein loss falls and albumin rises over weeks.

Albumin as a marker of overall health

In large studies, lower albumin is associated with higher mortality in hospital patients, people on dialysis, older adults and people with heart failure or cancer. This reflects the fact that albumin falls with inflammation, frailty and serious illness. For this reason, albumin is included in several prognostic scores. A single low value should prompt a search for its cause, rather than treatment of the number itself.

Albumin in the urine

Urine albumin is a separate test, measured in mg/L and usually expressed as the urine albumin-to-creatinine ratio (UACR). It detects small amounts of albumin leaking through damaged kidney filters, long before serum albumin falls. A UACR of 30 mg/g (3 mg/mmol) or more indicates increased albuminuria and is an early sign of kidney disease, especially in diabetes. Our UACR converter handles the mg/g ↔ mg/mmol conversion.

Albumin as a treatment

Human albumin solution is used intravenously in specific situations: after large-volume drainage of ascites in cirrhosis, in some cases of spontaneous bacterial peritonitis and hepatorenal syndrome, and in certain resuscitation settings. Giving albumin simply to correct a low blood level is generally not recommended, because it does not address the underlying cause and has not been shown to improve outcomes in most conditions.

What affects albumin results

• Hydration – dehydration raises albumin; over-hydration lowers it.
• Posture and tourniquet time – standing and prolonged tourniquet use raise results.
• Inflammation – lowers albumin within days.
• Laboratory method – BCG and BCP methods differ.
• Pregnancy – lowers albumin.
• Medicines – oestrogens can lower albumin slightly; albumin infusions raise it.

Comparing albumin results across laboratories

Because the BCG and BCP methods give different results, an apparent change in albumin may reflect a change of laboratory. For example, a person with kidney disease might have 3.4 g/dL in one laboratory (BCP method) and 38 g/L in another (BCG method). Converted, 3.4 g/dL is 34 g/L, so the second result is 4 g/L higher – a difference that could be largely methodological. When albumin feeds into a calculation, such as corrected calcium, the method can change the answer enough to move a result across a threshold. Ask which method your laboratory uses if you are tracking albumin closely or comparing results from different places.

Typical albumin values at a glance

These ranges are illustrative only and overlap widely; the cause of a low albumin must be determined clinically.

When to see a doctor

See a doctor if your albumin is below the reference range, particularly if you have swelling of the legs or abdomen, frothy urine (possible protein loss in the kidneys), jaundice, unexplained weight loss or chronic diarrhoea. Seek prompt care for rapidly increasing swelling, breathlessness, a swollen abdomen with fever or confusion in someone with known liver disease, or reduced urine output.