The feedback from high blood urea it is a fact that must immediately start a series of investigations in order to investigate the functionality of the kidney and the possible presence of renal insufficiency. Let's see what are the normal and altered levels of azotemia, the causes and the main symptoms related to elevated urea levels.
What are nitrogen, BUN and azotemia
- Nitrogen it is a very common element in nature: it is estimated to be the fifth most abundant element in the Universe. Its diatomic form (ie composed of two nitrogen atoms linked together by three high-energy covalent bonds) represents approximately 78% of the entire earth's atmosphere; it is also an important element in our organism, as it is essential for the correct functioning of many biological molecules, including DNA and proteins. However, being an element that participates in the formation of toxic compounds for the human body (such as ammonia), it needs to be constantly removed when it is in excess, a removal that occurs thanks to the functioning of the kidneys.
- With the initials BUN, that stands for Blood Urea Nitrogen, the urea nitrogen index present in the blood is indicated, an important parameter for evaluating the correct functioning of the kidneys. The BUN is obtained by dividing the amount of urea present in the blood by the constant number 2.14. Optimal BUN values range from 10 to 21 mg / dl of blood.
- BUN it is a parameter that instead evaluates the concentration in the blood of non-protein nitrogen (ie what must be removed from the body, deriving from the degradation of proteins no longer used because they are superfluous or damaged) by measuring the concentration of urea; azotemia therefore does not include the nitrogen involved in active proteins, that is, protein nitrogen.
What is urea
L'urea it is the molecule that is synthesized in our body in order to transport the excess nitrogen present in our body in the urine, which derives from the degradation of proteins. Urea is synthesized thanks to the urea cycle, an energy-intensive biological process, starting from the ion ammonium (which must be eliminated as it is potentially toxic to the brain) along with other compounds. The ammonium ion is obtained from the deamination of amino acids by transaminases, for this reason urea can be considered as the final waste product of the degradation of proteins.
Warning: do not get confused!
- Azotemia is synonymous with urea or BUN? Theoretically yes, the term azotemia should indicate the amount of nitrogen present in the blood. In fact, the term azotemia is used as a synonym for blood urea concentration. Urea, however, as we have seen, is composed of about half of nitrogen, and the remaining half of other elements. Even if by now saying high urea or high BUN is considered to have the same meaning, in reality BUN would correspond to BUN, which we saw in the previous paragraph to be urea nitrogen, which is obtained by dividing the amount of urea by 2.14.
- Is blood urea uremia? Theoretically, the concentration of urea in the blood is scientifically named uremia. In fact, the term uremia is used to indicate an advanced stage of renal failure characterized by high levels of urea in the blood but also by a series of typical symptoms and signs, such as leg edema, nausea, swelling of the face, high levels of potassium in the blood (hyperkalaemia) and reduced calcium levels (hypocalcaemia).
Azotemia: normal and high levels
- High blood urea nitrogen levels in adults: BUN greater than 43 mg / dL (43 milligrams per deciliter).
- High blood urea nitrogen levels in children: BUN greater than 26 mg / dL (26 milligrams per deciliter).
If it is considered appropriate to carry out the test, it is necessary to fast at least for the 12 hours preceding it, to ensure that the values are not altered by the diet. Furthermore, even intense physical activity (which causes the degradation of part of the muscle proteins) in the days before the test could cause alteration of the results.
Causes of high blood urea
BUN is often associated with a problem primarily affecting the kidneys. In fact, to ascertain that azotemia is linked to renal malfunction it is advisable to perform other tests that can help identify kidney damage, such as the examination of creatinine (another waste product containing nitrogen, deriving from creatine); if you have high blood urea nitrogen and creatinine, it can lead to a situation of renal dysfunction. High blood urea nitrogen can also be caused by a diet that is too rich in protein or by a state of temporary dehydration, frequent in sportsmen after intense sweating, or in the elderly who do not hydrate or use diuretic drugs.
- It indicates how prerenal azotemia an accumulation of urea in the blood not due to the presence of primary damage to the kidneys, but to a renal blood hypoperfusion (a condition that causes poor blood flow in the kidneys). This situation can in turn be caused by other factors, such as
- renal artery stenosis: reduction of the lumen of the renal artery, the artery that carries blood to the kidney
- hypovolemia from loss of fluids, with poor renal blood supply: hypovolemia consists of a decreased volume of blood circulating in the body, for example due to haemorrhages, dehydration or burns.
- vasodilation hypovolemia: in this situation the amount of blood circulating is constant, but the overall volume of blood vessels suddenly increases, causing a hypovolemia defined as “effective”. A classic example is anaphylactic shock, in which vasodilation is caused by an allergic reaction to a food or to the poison of an insect.
- heart failure: it can be a cause of poor blood supply to the kidneys (in this condition the heart cannot pump an adequate amount of blood and the blood flow is reduced).
- Among the causes of high blood urea secondary to kidney damage, we remember:
- Diabetes mellitus
- Medicines which damage kidney tissues
- Glomerulonephritis acute and chronic
- L'azotemia of post-renal origin it is secondary to an obstruction to the normal outflow of urine in the excretory tracts. For example, very advanced prostatic hypertrophy, prostate cancer or a urethral stone can partially or completely block urine output, causing stagnation upstream of the obstruction and possible kidney damage.
- Among the causes of high blood urea nitrogen related to food, first of all, there is an excessively low-calorie diet: in these cases, to compensate for the low energy intake, the body will tend to degrade the body's structural proteins in order to obtain the necessary energy (in the absence of adipose tissue); a mechanism similar to the previous one also occurs in the case of very intense physical activity (body builder activity). In a diametrically opposite way, an excessively protein diet can also cause an increase in blood urea.
There main cause of high blood urea nitrogen, namely kidney failure it can also be classified according to the rate at which it occurs: acute renal failure and chronic renal failure.
- L'ANGER (acute renal failure) involves the sudden decrease in the filtration capacity of the kidneys; it is a syndrome attributable to various factors, and if promptly identified and treated it can also be completely reversible. The most frequent causes of IRA can be:
- renal ischaemia, i.e. a reduced blood supply to the kidney, secondary to a sudden reduction in diameter or occlusion of the renal artery, a reduction in the volume of circulating blood or a heart pump deficiency, leading to the development of acute tubular necrosis .
- taking nephrotoxic drugs: the drugs most frequently responsible for iatrogenic IRA are antibiotics, anti-inflammatory and immunosuppressive drugs.
- postrenal causes such as a sudden obstruction of the excretory passages (for example due to a stone in the urethra).
- L'IRC (chronic renal failure) is a condition that develops gradually and steadily over time, and the damage it causes is often irreversible. Causes of chronic renal failure can be:
- Type 1 and 2 diabetes mellitus: the presence of hyperglycemia, the result of suboptimal control with diet or hypoglycemic therapy, causes slow but progressive damage to the renal arteries.
- Chronic pyelonephritis, bacterial infection that chronicizes and progressively damages the renal parenchyma
- Constant obstruction of the urinary tract
- Taking nephrotoxic drugs, that is, drugs that damage the kidneys in the chronic
- Polycystic kidney (kidney that develops a large number of cysts): causes progressive kidney dysfunction.
Symptoms of high azotemia
THE symptoms of high blood urea nitrogen they are generally:
- frequent urination (pollakiuria),
- dark-colored urine
- urine containing blood (hematuria),
- poor appetite (hyporexia),
- fatigue and exhaustion (asthenia),
- frequent swelling of the hands and feet,
- nausea and vomit,
BUN and nutrition: foods to avoid in case of high BUN
What to eat in case of high azotemia? To bring the blood urea nitrogen back to adequate levels, it is advisable to drink 1.5-2 liters of water per day, in order to limit the dehydration of the body, a possible cause of high blood urea. This obviously does not apply if the doctor who follows you has indicated a different amount of fluids to take, which takes into account any other concomitant therapy and pathologies.
In addition, it is advisable to follow a specific diet for high azotemia, which does not include foods excessively rich in proteins, such as eggs, red meat, blue fish (cod, hake, tuna and anchovies), cheeses and legumes (including soy and beans) ; foods too rich in electrolytes such as salt, which dehydrates the body during its elimination, are also not recommended. On the other hand, cereals are very suitable, especially whole grains (which limit the presence of functional alterations affecting the kidneys), fruit and in particular vegetables, rich in water and low in proteins.
High azotemia: remedies and treatments
What to do in case of high blood urea nitrogen? The generic remedies that must be adopted mainly concern nutrition, and therefore it is advisable to follow the instructions indicated above. Bad habits such as smoking and especially alcohol consumption (which can cause hepatorenal syndrome and hormonal imbalances at the adrenal level) must be stopped immediately; if you are also taking medicines, it is important to consult your doctor as soon as possible, as some medicines can have adverse effects on the functioning of the kidneys.
Finally, since azotemia is a condition that can be caused by such a large number of syndromes, it is advisable to first identify the cause through specific analyzes, then consult your doctor to follow a treatment suitable for the situation.