Protein in urine

It is called proteinuria and means that there is an excessive amount of protein in the urine. This phenomenon occurs when the kidneys, which have the task of filtering the blood by expelling waste substances, do not work well: the result is that components that should remain in the blood, such as proteins, escape the “renal sieve” (the glomerular basement membrane) and are expelled into the urine.

Why do the kidneys malfunction?

The causes can be different and it is not necessarily the case to be frightened: often, in fact, the presence of proteins in the urine in quantities higher than normal can be a completely physiological condition and therefore normal. It occurs frequently in case of pregnancy, high stress, fever or very intense physical activity.

In some children and adolescents it manifests itself in the form of orthostatic proteinuria: it is associated, that is, with standing (and therefore it is more marked during the day than at night), does not require special care and tends to disappear in adulthood.

However, there are situations in which proteinuria is a symptom of more or less serious kidney damage. The more these organs are damaged, the greater the size and quantity of proteins that escape filtration and collect in the urine, as well as the number of symptoms to which it will be accompanied (first of all hematuria, or the presence of blood in the urine).

Proteinuria can be the consequence of several kidney diseases, such as:

• diseases of the renal glomeruli, small “balls” that filter the blood at the level of the kidneys. When they don’t work properly, some circulating proteins, mainly albumin, can pass into the urine. These pathologies can be primitive, when they originate inside the kidney and do not involve other organs (such as immunoglobulin glomerulonephritis, a chronic renal disease or membranous glomerulonephritis, or even focal and segmental glomerulosclerosis) or secondary, when they are the manifestation of a disorder present at the level of other organs, as in the case of systemic lupus erythematosus (a chronic autoimmune disease that causes inflammation of the body’s tissues), diabetes mellitus, high blood pressure (also known as high blood pressure), amyloidosis (a rare disease due to abnormalities of protein molecules, causing dysfunction and organic insufficiency), and many other diseases;
• diseases of the renal tubules, when proteinuria occurs but the share of albumin in the urine is low (such as interstitial nephritis).

Proteinuria can also be caused by blood diseases, such as certain cancers, or by anemia and heavy metal poisoning.

How much protein?

It may happen that a minimum amount of protein (less than 200 mg) and albumin (less than 30 mg) can be detected in the urine collected within 24 hours. This is a rather common phenomenon and is not a symptom of any kidney damage.

When, on the other hand, the concentrations of these substances in the urine increase, based on the value recorded in 24 hours, it is possible to speak of:

Exams to be done

In most cases proteinuria is a disorder that does not give specific symptoms. At most, the production of urine more foamy and dense than normal may be suspicious, while situations in which swelling of the ankles or face can be observed are quite rare, or a slight weight gain, due to fluid retention, in turn caused by the reduced presence of circulating proteins.

The best way to detect proteinuria is to perform simple laboratory tests. These are routine analyzes, which evaluate the concentration of proteins in the urine, to be carried out on a fresh sample, collected at the first or, at most at the second, morning urination.

If the results of the test are such as to rule out the “benign” cause, the doctor may request another morning urine sample or urine collection within 24 hours to perform more accurate measurements. In the event that you suspect kidney disease – or want to monitor its evolution if already diagnosed – you can also prescribe other tests useful to evaluate kidney function (blood, such as creatinine and azotemia, and diagnostic imaging, such as ultrasound) and a visit to a specialist in nephrology.

Only if the pathology is ascertained, the attending physician and the nephrologist, to better define it, could suggest a kidney biopsy, that is to say the taking of a small sample of kidney tissue.

Who should keep them under control?

Some people should regularly check for proteinuria and albuminuria. Here are the conditions under which
it is good to undergo the examination.

What about therapies?

To deal with this disorder it is important to understand the overall situation of the person. For example, those suffering from diabetes or hypertension have a higher chance of developing proteinuria and the therapy consists mainly of:

• loss of body weight in overweight individuals,
• practice regular physical activity,
• quit smoking,
• reduce the use of salt in the kitchen.

The goal is to keep blood pressure values as close to normal as possible (below 130/80 mmHg), as well as blood glucose values (i.e. the concentration of glucose in the blood) and glycated or glycosylated hemoglobin (a molecule resulting from the union between hemoglobin, the protein that transports oxygen to tissues, and glucose circulating in the blood).

There is also the possibility of using some types of drugs that can have positive effects, including ACE inhibitors (which are also used in the treatment of hypertension, congestive heart failure and previous myocardial infarction) and angiotensin II antagonists (a class of drugs very effective in counteracting hypertensive phenomena).

In the event that proteinuria depends directly on a kidney disease, the therapy will aim to solve the disease, thus eliminating the excessive loss of protein in the urine at the root.

In conclusion, the way in which to deal with this disorder depends on a series of individual factors and, above all, on the triggering cause. It is therefore essential that the nephrologist indicates the therapy to be followed: he will eventually prescribe further analyzes and will evaluate the right steps to take.