Albumin it is the main protein produced by the liver, and it is a very important substance for the body. Albumin has many functions including the maintenance of oncotic pressure (avoiding water retention and declining edema), the transport of waste substances, hormones, drugs and many other metabolites, the maintenance of a pH within the normal limits.
The analysis of serum levels of albumin, carried out with a laboratory technique called serum protein electrophoresis is a very important test, which allows you to guide the doctor towards specific pathologies. A high albumin will have to exclude a state of dehydration and hypovolemia as a first hypothesis, while a low albumin (sometimes complicated by symptoms such as declining edema and ascites) will lead the clinician to investigate liver and kidney function, as well as intestinal function and the type of nutrition of the person concerned.
What is albumin? Albumin is a protein found in plasma and synthesized by liver cells. Its name partly recalls the composition of the egg and, in fact, is mostly present in its albumen (from which it takes its name) but also in the milk; for this reason it would be more correct to speak of a group of albumins, since each albumin mentioned up to now obviously has different properties. It is characterized by an important molecular weight, 69,000 u, and is the main of the plasma cells, constituting about 60% of the total protidemia. However, albumin is also present in interstitial fluids.
The elemental chemical formula of albumin is C53-H6.98-N16-S 1.84. Its coagulation, carried out in a solution with a low salt content and 1% concentration, occurs at 50 ° C while, if the coagulation is carried out directly on the natural blood plasma, it begins at 60 ° C.
By entering more into the chemical composition of albumin, during the hydrolysis process these molecules return almost all the amino acids. In animal albumin there is only the lack of glycol which, however, is present in vegetable albumin.
Serum albumin (blood albumin) can be obtained by crystallization of the blood but there is a particularity, because whatever methodology is chosen to obtain its crystallization, only half of the serum albumin crystallizes. This particular fact has prompted several researchers to hypothesize that, therefore, two different types of albumin are present in the blood, mixed together.
The functions of albumin
Having made a necessary chemical-physical excursus on the properties of albumin, it is necessary to understand why this molecule is so important in the functioning and organic balance of the human body.
It is no exaggeration to consider it fundamental for biological equilibrium, since its presence allows to stabilize, regularize and balance the viscosity and volume of the blood flow. Its role is crucial in the maintenance of oncotic pressure, that is the osmotic pressure exerted in the blood vessels by colloidal solutions. An optimal oncotic pressure value, which should normally be 20mmHg, ensures optimal distribution of fluids between vessels and tissues.
In addition to performing this very important balancing function, however, albumin is also a vehicle for the transport of metabolites in the blood. In addition to drawing water into the bloodstream (18 grams for each gram of albumin), this molecule also carries bilirubin, thyroid hormones and numerous other substances.
Furthermore, in case of need, the human body also uses albumin as a reserve of amino acids, a rather large supply that helps the body to obtain proteins in case of deficiency.
Albumin is a protein that also plays an important role in buffering organic pH, helping it to return to normal values when it becomes excessively basic or acidic.
Where is albumin found?
As already specified, in the human body and, in general, in vertebrate animal organisms, albumin is a fundamental component of plasma, the concentration of which is on average between 3.5 and 5 grams per deciliter. An important presence, therefore, but albumin it is also found in other body fluids, albeit to a lesser extent. In fact, its presence is also reported in interstitial liquids, ie a water-based solution found in the spaces between the cells of every organic tissue. Obviously, traces of albumin are also found in exudates and transudates, that is, effusion fluids which, however, have a different origin. However, a higher concentration of albumin is recorded in the exudate, resulting from an ongoing inflammatory process.
Particularly interesting is the presence of albumin in the urine: in normal conditions, in fact, this molecule is almost absent in this fluid and, if its presence is marked, the albumin in the high urine is a symptom of a pathological process in progress to be evaluated with extreme attention.
Exiting for a moment from human albumin, also called serum albumin, this protein molecule is present in the egg or, better, in its clear. In reality, in this case, we are talking about two different types of albumin:
- with albumin
With different crystallization capabilities.
Milk albumin is also interesting, much more similar to whey than egg. It differs from blood albumin exclusively in a lower rotation coefficient.
Normal values of albumin
Normal albumin values, as already mentioned, must be between 35 and 55 grams per liter. The albumin variation is detected by protein electrophoresis, a simple laboratory analysis that is conducted in order to separate the whey proteins, in order to identify them and evaluate their presence.
Furthermore, under normal conditions, the Albumin / Globulin ratio must be between 1.1 and 2.5%, while the Albumin / Creatinine ratio must be less than 17 mg / g for males and 25 mg / g for female individuals.
Let's see how a variation of these values can indicate an ongoing problem.
High albumin levels are found in numerous situations, but in most cases these are not irrecoverable. The main cause of high albumin is in fact hemoconcentration, i.e. the increase in the concentration of substances contained in the blood, due to a reduction in the circulating volume. This often happens due to a loss of fluids with consequent dehydration, for example through heavy sweating, profuse diarrhea or too abundant diuresis. If we were to take a blood albumin sample from an athlete at the end of a long-term running competition, we would almost certainly find elevated albumin levels. Fortunately, by replenishing lost fluids, hyperalbuminemia is also easily corrected. But let's see in detail the main situations characterized by elevated albumin.
High albumin: causes
High albumin values can be caused by different cases. As mentioned before, the concentration of albumin in the blood is verified by means of a protein electrophoresis procedure. The main causes of high albumin can be:
- High level of dehydration (prolonged vomiting and dysentery)
- Extensive burns over large parts of the body
- Addison's disease
- Burger disease
- Certain kidney conditions, such as glomerulonephritis.
High albumin: symptoms
In the case of high albumin, specific symptoms cannot be identified, because each cause that contributes to an excessive value of albumin in the blood has a specific symptomatology. Hyperalbuminemia is therefore asymptomatic. In the case of the specific pathologies that cause it, some symptoms may occur, such as:
- Breathing problems (pulmonary sarcoidosis)
- Hypercalcemia (renal sarcoidosis)
- Joint pain
- Dehydration (Addison's disease)
- Skin discoloration (Addison's Morno)
Hypoalbuminemia, or the finding of reduced albumin values in the blood, underlies a large number of situations, mostly pathological. In most cases, reduced albumin production, secondary to liver or bowel malfunction, or increased albumin loss, usually secondary to increased renal (and urinary) or intestinal loss, is the basis of hypoalbuminemia. of this precious protein. But let's see in detail the main causes of hypoalbuminemia.
Low albumin: causes
Low levels of albumin in the blood are the alarm bell of some ongoing problems with different degrees of severity. Among the main causes of low albumin we find:
- Increased catabolism (prolonged fever, cachexia, hyperthyroidism, neoplasms, etc.)
- Poor absorption (celiac disease, protein-dispersing enteropathies)
- Liver disorders, such as cirrhosis
- Kidney disorders, such as severe renal failure and / or nephrotic syndrome
- Hereditary deficiency
- Birth control pill
- Autoimmune Diseases
- Hormonal impairment
Low albumin: symptoms
Also in this case, a specific symptomatology cannot be defined, because hypoalbuminemia is not in itself a pathology but a condition that is accompanied by real diseases and if the values are not excessively low, hypoalbuminemia is almost asymptomatic . Symptoms that could indicate an albumin deficiency, caused by pathologies proper, can be
- Edema (fluid retention, especially in the lower limbs, the so-called sloping edema)
- Muscle cramps
- Ascites (fluid in the abdomen)
- pleural effusion (accumulation of fluid in the pleural cavity)
Low albumin: what to eat
In case of hypoalbuminemia, it may be useful to follow a diet rich in proteins, which is one of the main remedies especially in the case of not excessively low values. One of the most recommended foods to raise albumin levels is, of course, eggs, one of the foods richest in this protein. Also important is the increase in milk intake. Also important is the intake of large portions of fruit and vegetables, which help fight water retention resulting from albumin. Obviously, you need to go to a doctor for a correct prescription.
Albumin in urine: significance and associated conditions
High urine albumin is symptomatic of the presence of certain diseases. One of the main causes is late stage diabetes, as the kidneys are no longer able to work at full capacity. this is the main cause of high levels of albumin in the urine while lower values are usually symptomatic of excessive protein intake, excessively intense training or an ongoing pregnancy. The presence of protein in the urine is defined by microalbuminuria, if limited to 300 mg of protein in 24 hours, or frank proteinuria if greater than 0.3 g of protein lost every day. Usually, the recorded levels are equal to 20-200 µg per minute but different values in excess are a symptom of a nephropathy.
High and low albumin in pregnancy
A low value of albumin in pregnancy it is physiological and absolutely normal, since the liver reduces its production and, with the increase in the volume of blood circulation, its quantity is diluted in a higher quantity of plasma. Obviously, if the values drop too much, you are facing a liver or thyroid problem. The presence in the urine during pregnancy, however, especially if in high quantities, can be a problem. It can be one of the symptoms of gestosis, which is manifested by excessive swelling in the limbs, accompanied by abnormal blood pressure.Tags: Liver Laboratory medicine Proteins