Uric acid and urea: what is the difference?

Often confused in a blood test, uric acid and urea do not have the same meaning. These indicators provide very different information on health, particularly on the kidneys and the risk of gout. We take stock to better understand your blood tests.

L’uric acid is a natural waste from the breakdown of purinesmolecules present in our cells but also in certain foods (red meat, abattoirs, seafood, alcohol). It is transported in the blood (we speak ofuricemia) Then eliminated by the reins in the urines.

In case ofexcess d’uric acid(hyperuricemia), there may be a crystallization of uric acid in the form ofurate in the joints. It is this mechanism which causes the gout attack characterized by a sudden joint pain often located at big toe.

L’urea is also a waste from the human bodybut it comes from the degradation of proteins (animal products, legumes…). It is produced by the foiethen eliminated by reins via urine.

The urea dosage (or uremia on a blood test) makes it possible to assess:

We often talk about creatinine ureabecause these two parameters are analyzed together to explore kidney function.

This is a common question, because these two parameters often appear together in blood tests even though they do not have the same function at all. “These two markers are no longer prescribed in simple routine assessments today. They are requested in very specific clinical situations,” explains nephrologist Thomas Stehle.

To remember: Uric acid points more towards a metabolic problem like gout, while urea mainly provides information on how the kidneys filter and eliminate waste.

There are several reasons for this confusion:

“They are both waste products eliminated in the urine, which creates confusion, but their medical meaning is very different,” recalls the nephrologist.

Beyond : hyperuricemia

These normal values ​​may vary slightly between laboratories.

We often talk about high values, but rates too low may also appear for some patients.

A low urea is generally little concern.

It can be explained by:

In the majority of cases, this has no clinical consequences.

And low blood uric acid is also rare and most often benign.

Unlike a high uric acidit is generally not associated with symptoms.

Not always. High urea may be linked to:

“In the absence of kidney damage, diet alone has little effect on urea. On the other hand, in the event of renal insufficiency, excessive protein intake can aggravate the elevation,” specifies Doctor Thomas Stehle.

In more advanced forms: “When creatinine is high, GFR lowered and urea is very high, this can be a sign of worsening kidney failure and sometimes lead to discussion of dialysis,” he adds.

An accumulation excessive uric acid can lead to:

But one hyperuricemia maybe asymptomatic. These are mainly the gout symptoms which guide the diagnosis.

Several measures can help limit a high uric acid level :

Of the drug treatments can also be prescribed in cases of gout.

For a urea too highthe solutions are often simple:

In case ofkidney failureyour doctor will opt for appropriate treatment depending on the stage (nephroprotection measure).

It is recommended to consult a doctor in case of:

Do not interpret your results alone remains essential.

We often hear that certain foods, such as red meat or the dairy products“acidify the body” This idea is easily confusing, because it has no direct link with uric acid or urea.

In reality, theacid-base balance of the body, that is to say the pH sanguineis very tightly regulated by the lungs and kidneys and varies very little in a healthy person. The digestion of animal proteins may well produce an acidic load, notably through the formation ofsulfuric acidwhich the body must then buffer and eliminate. But this does not mean that eating red meat “acidifies the body” in the sense that it would increase urea or uric acid by the same mechanism. Here again, we must distinguish between different biological phenomena.

In the same way, thediabetic ketoacidosis has nothing to do with uric acid: it is a serious complication of diabetes, linked to accumulation of ketone bodies in the blood.

Finally, the notion of “acidifying foods” must be handled with caution and without confusing pH, urea, uric acid and ketoacidosis.