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Albuminuria is a symptom in which small molecule proteins (so-called albumin) are present in the urine. It is assumed that up to a certain concentration albuminuria is a physiological phenomenon (normoalbuminuria), but higher values ​​should always be a cause for concern as they may indicate a disease that is still clinically silent at the moment.


  1. What are albumin?
  2. Causes of albuminuria
  3. Albuminuria and Chronic Kidney Disease
  4. Albuminuria: clinical symptoms
  5. Albuminuria diagnosis
  6. Albuminuria as a prognostic factor
  7. Albuminuria: recommendations

Albuminuriain medical terminology only tells us that albumin has appeared in the urine, not necessarily in abnormally high concentrations. However, in this article, in order not to mislead the reader, for the sake of simplicity it can be assumed that the term "albuminuria" is a pathological phenomenon.

What are albumin?

When talking about albuminuria, it is worth mentioning first what albumin itself is. Albumin are proteins that occur naturally in the plasma of animals as well as in plants. The liver is responsible for their production in our body.

Albumin accounts for over half of all proteins in the blood, and their presence is essential for the proper functioning of the entire body.

In addition to maintaining normal oncotic blood pressure and being an important buffer in it, albumin also plays a role in the transport of numerous substances. In some disease states, their production may be reduced or excessively "escaped", with negative consequences.

Causes of albuminuria

Under physiological conditions, the glomeruli only excrete a small amount of albumin. If the structure of the kidneys is damaged, the level of albuminuria rises. Such a condition can be caused, for example, by long-term, ineffectively treated arterial hypertension, or many years of type 1 diabetes and type 2 diabetes. It is believed that albuminuria may be an indicator of damage not only to nephrons, but also to all small vessels in the body.

Various chronic kidney diseases in their course cause a gradual loss of nephrons, as a result of which the remaining ones due to overexploitation alsothey slowly lose their function. Some authors believe that kidney damage continues even when the glomeruli are in relatively good condition. According to them, this is because albumin significantly damages the kidney's tubules by activating pro-inflammatory cells in them.

Diseases that may lead to albuminuria include:

  • diabetes
  • hypertension
  • glomerulopatie
  • renal vascular disease
  • multiple myeloma
  • kidney cancer
  • polycystic kidney disease
  • systemic connective tissue diseases
  • significantly enlarged prostate or other obstruction in the outflow of urine
  • interstitial inflammatory diseases

Albuminuria and Chronic Kidney Disease

The level of albuminuria according to the KDIGO guidelines from 2012 is one of the criteria for classifying chronic kidney disease into a specific stage. The amount of albuminuria is determined by the albumin / creatinine ratio (ACR) in any urine sample or the level of albumin, which is measured in a urine sample from its daily collection. The following categories of albuminuria can be distinguished:

  • A1 - loss of up to 30 mg of albumin per day or ACR ratio<30 mg/g
  • A2 - loss of 30-300 mg of albumin per day or ACR ratio of 30-300 mg / g
  • A3 - loss of over 300 mg of albumin per day or ACR ratio>300 mg / g

If albuminuria exceeds 300 mg a day, it is called overt proteinuria.

Albuminuria: clinical symptoms

Albuminuria is not a disease in itself, but only a symptom of an illness that occurs in the body. Sometimes, however, it can be accompanied by other symptoms related to the leakage of proteins with the urine. Albumin in the vascular bed is responsible for maintaining the correct oncotic pressure. This means that they prevent plasma from escaping from the vessels into the tissue spaces that surround them. Mild albuminuria is unlikely to result in any additional clinical symptoms. However, even at higher values, when the albumin is not enough, fluids will run out of the vessels and swelling may occur, mainly around the ankles. Characteristic foamy urine can also be observed with proteinuria.

Albuminuria diagnosis

It should be remembered that measuring the level of albumin in a single urine sample, i.e. the albumin / creatinine ratio, is a screening test that gives only an idea of ​​the condition of the kidneys. The diagnostic test is the measurement of albuminuria in the 24-hour urine collection and only this method is reliable enough to make an accuratediagnosis. The diagnosis of albuminuria must always be accompanied by a general urine test, which will help us to detect, for example, possible inflammation, because only such a set of tests guarantees us an accurate diagnosis. Patients for whom we want to carry out urine tests may not currently show symptoms of acute conditions or exacerbations of chronic diseases, inflammations, they cannot undertake intense physical exertion, because such situations may distort the results of laboratory tests.

Albuminuria as a prognostic factor

It has been proven in many studies that albuminuria remains an independent factor that increases the risk of diseases such as cardiovascular events (e.g. heart attack, stroke), heart failure, and also leads to the progression of chronic kidney disease and increases the risk of death. Screening tests that can reveal the presence and degree of albuminuria should be included in patients with chronic kidney disease, diabetes, hypertension, and those with a family history of cardiovascular disease. In addition, no screening for albuminuria is recommended in people who are asymptomatic and at low risk. However, it should be remembered that albuminuria can also appear in he althy people when they are accompanied by obesity, a diet rich in proteins, intense exercise, various inflammations and infections, and also in smokers.

Albuminuria: recommendations

If albuminuria has appeared in a person with no history of cardiovascular, metabolic or nephrological diseases, you can only have a checkup to see if it was transient and you can find an explanation for its presence. However, if albuminuria is detected in a chronically ill patient, it should be quickly under the supervision of a nephrologist.

Patients with hypertension should check their blood pressure regularly at home and see a doctor if necessary, so that it is kept within the correct range at all times.

Often, in the absence of contraindications, patients with albuminuria receive angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor antagonists (ARBs) because they have proven renoprotective effects and are recommended for use in patients with albuminuria, even when it is not accompanied by arterial hypertension. While patients with type 1 diabetes mellitus may be referred to a nephrologist only five years after the diagnosis of the disease, when diagnosed with type 2 diabetes, such a patient should go to such an appointment fromright away. It is related to the different course of both types of diabetes. Type 1 diabetes is very dynamic and is detected immediately. Type 2 diabetes, on the other hand, can last for many years and go undiagnosed, damaging the kidneys all the time. The diagnosing doctor never knows how long the kidneys have been damaged, so full diagnostics should be implemented right away. In both groups of diabetic patients, monitoring of possible albuminuria should be performed once a year.

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