Albumin: what it is, what it tells you and why we test it

Albumin is the most common protein in your blood, and your liver makes it. It keeps water inside your blood vessels and carries many substances, including calcium. Its level says something about your liver, your diet and inflammation.

Why we test it

Your liver makes albumin every day. It keeps water inside your blood vessels and carries many substances around, from calcium to some medicines.

When it drops, there is usually a reason to find. The most common is inflammation or an illness. More rarely the liver, the kidneys or a very poor diet are behind it.

It also helps read other tests: measured calcium, for example, depends on how much albumin there is.

What it tells you, and what it does not

If it is low, there is often inflammation, and CRP helps tell. It does not have to mean you eat too little protein, even though that is the most common conclusion.

If it is high, it almost always just means your blood was a little concentrated at the draw, for example from too little water.

And it comes back up slowly: an acute illness can make it drop within a few days, but it then takes weeks to recover. So a low value can reflect a recent illness, even if you feel well today.

That is why it is read together with other tests:

Normal albumin levels

The lab decides what is normal. On some reports it is 4.02 to 4.76 g/dL. Many labs print wider limits, because they also depend on the method: your own report’s limits are the ones that count.

Many reports give it in g/L instead of g/dL. It is the same measurement: divide by ten. For example, 40.2 g/L is 4.02 g/dL.

It drops a little with age, even in healthy people. In pregnancy it is normally lower.

In the Rosa report you also see your optimal range, read together with CRP and your other liver tests.

What your result means

Find the row for your result, in g/dL: if your report uses g/L, divide by ten. If your report prints different limits, its limits count. Which values are dangerous? There is no single cut-off: what counts is the cause, and whether you have swelling or other symptoms.

If your albumin is low or high

High albumin in the blood: usually too little water

In the blood, a high albumin almost always just means the blood was more concentrated than usual. For example, you drank little, sweated a lot, or the tourniquet stayed on a long time. It is not an illness, and it usually settles once you drink normally.

High albumin in urine is a different test, even though it shares the name. There should be almost no albumin in urine: if there is, your kidneys may be letting it through, and a high result should be shown to your doctor.

Urine albumin has a test of its own:

What can skew the result

A few things change the number for a while. It helps to know them before you read it.

When to worry

Talk to your doctor if:

Frequently asked questions

My report says g/L: how do I read it? It is the same measurement in another unit. Divide by ten: 40.2 g/L is 4.02 g/dL, and 47.6 g/L is 4.76 g/dL.

Why is calcium read with albumin? A good part of the calcium in your blood travels attached to albumin. If albumin is low, measured calcium looks lower than it really is, and your doctor takes that into account.

Does albumin powder raise the albumin in your blood? Not directly. Albumin powder is egg white: a protein-rich food like any other, which your body breaks down. The albumin in your blood is made by your liver.

Do I need to fast for an albumin test? Not for albumin. It is usually done with other tests that do need fasting, though, so it is best to arrive fasted. Do drink water: too little makes the number look higher.

How often should it be checked? For people who feel well there is no fixed rule: Rosa measures it twice a year. It changes slowly, so repeating it after a few days says little. If it is out of range, your doctor decides when to check it again.

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