Stages of renal failure: acute( initial, oligoanuric, polyuric) and chronic( polyuric, terminal)

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Renal failure is a serious complication of various renal pathologies, and is very common. The disease can be treated, but the organ does not recover. Chronic renal failure is not a disease, but a syndrome, that is, a set of signs indicating a violation of the functionality of the kidneys. Causes of chronic failure may be different diseases or injuries, as a result of which the organ is damaged.

Stages of renal failure

From the work of the kidney depends water, nitrogen, electrolyte and other types of metabolism in the human body. Renal failure is evidence of non-fulfillment of all functions leading to the violation of all types of balance at once.

The most common cause is chronic diseases, in which the parenchyma of the kidney is slowly destroyed and replaced by a connective tissue. Renal failure is the last stage of such ailments - pyelonephritis, urolithiasis and the like.

The most revealing symptom of pathologies is daily urine volume - diuresis, or minute. The latter is used in the examination of the kidneys by the method of clearance. In normal operation of the kidney, urinary excretion is about 67-75% of the volume of the fluid. At the same time, the minimum volume required for the operation of the organ is 500 ml. Therefore, the minimum amount of water that a person should consume per day is 800 ml. With a standard water consumption of 1-2 liters per day, diuresis is 800-1500 ml per day.

In renal failure, the volume of urine changes significantly. In this case, there is an increase in volume - up to 3000 ml, and a reduction of up to 500 ml. The appearance of anuria - a diuresis of daily volume of 50 ml, is an indicator of kidney failure.

There are acute and chronic renal failure. The first is characterized by rapid development of the syndrome, pronounced symptoms, severe pain. However, most of the changes that occur with ARF are reversible, which allows the recovery of kidney function in appropriate weeks with appropriate treatment within a few weeks.

Acute renal failure

ARF is a sudden abrupt abnormality of the organ function associated with the suppression of the excretory function and the accumulation of nitrogen metabolism products in the blood. At the same time there is a breakdown of water, electrolyte, acid-base, osmotic balance. Changes of this kind are considered to be potentially reversible.

OPN develops within a few hours, less often within 1-7 days and becomes such if the syndrome is observed for more than a day. Acute renal failure is not an independent disease, but a secondary one, which develops against other diseases or traumas.

The reason for OPN are:

• low blood flow velocity;
• tubular damage;
• violation of urinary outflow due to obstruction;
• destruction of the glomerulus with loss of capillaries and arteries.

The reason for the occurrence of acute renal failure is the basis of the relevant qualifications: on this basis, prenatal acute insufficiency is distinguished - 70% of all cases, parenchymal 25% and obstructive - 5%.

According to medical statistics, the causes of such events are:

• surgical intervention or trauma - 60%.The number of cases of this kind is constantly growing, because it is associated with an increase in the number of operations in conditions of artificial circulation;
• 40% associated with treatment. The use of nephrotoxic drugs, necessary in a number of cases, leads to the development of acute renal failure. In the same category can be attributed acute poisoning with arsenic, mercury, mushroom poison;
• 1-2% appear during pregnancy.

Another classification of the stages of the disease, related to the patient's condition, is used, there are 4 stages:

• initial;
• is an oligoanuric;
• polyurethane;
• recvaluation.

Causes of acute renal failure

Initial stage

Symptoms of the disease depend on the causes and nature of the underlying disease. They are caused by the action of a stressful factor - poisoning, loss of blood, trauma.

• So, with an infectious organ damage, the symptoms coincide with the symptoms of general intoxication - headache, lethargy, muscle weakness, fever may occur. When complicating the intestinal infection, vomiting and diarrhea may occur.
• If OPN is a consequence of poisoning, then anemia, signs of jaundice, there may be seizures.
• If the cause is an acute kidney disease - glomerulonephritis, for example, in the urine can be observed blood, in the lower back there is a lot of pain.

Diagnosis at the initial stage is extremely difficult. If OPN is observed against the background of an infectious disease or acute poisoning, the ailment during treatment is taken into account, since the damage to the kidney during poisoning is quite natural phenomenon. The same can be said for cases when the patient is prescribed nephrotoxic drugs.

Urine test at the initial stage indicates not so much on the arrester as to the factors provoking the failure:

• relative density with prerenal arterial arrest above 1.018, and at a renal below 1.012;
• possible small proteinuria, the presence of granular or cellular cylinders with renal arterial nephrotoxic origin. However, in 20-30% of cases this feature is absent;
• with trauma, tumor, infection, urolithiasis in the urine show more erythrocytes;
• a large number of white blood cells indicates infection or allergic inflammation of the urinary tract;
• if uric acid crystals are detected, urate nephropathy can be suspected.

At any stage, arthritis is prescribed a bacteriological analysis of urine.

The general blood test corresponds to the primary disease, the biochemical at the initial stage can give data on hyperkalemia or hypokalemia. However, weak hyperkalemia - less than 6 mmol / l, does not cause changes.

Clinical picture of the initial stage of arterial hypertension

Oligoanuric

This stage in ARF is the most severe and can pose a threat to life and health. Symptoms are much better expressed and characteristic, which allows you to quickly establish a diagnosis. At this stage, the blood rapidly accumulates the products of nitrogen metabolism - creatinine, urea, which are excreted in the healthy body with urine. The absorption of potassium decreases, which destroys the water-salt balance. The kidney does not perform functions to support the acid-base balance, as a result of which metabolic acidosis is formed.

The main signs of the oligoanuric stage are as follows:

• decrease in diuresis: if the daily volume of urine drops to 500 ml, this indicates oliguria, if up to 50 ml - anuria;
• intoxication with metabolic products - skin itching, nausea, vomiting, tachycardia, rapid breathing;
• marked increase in blood pressure, conventional antihypertensive drugs do not work;
• confusion, loss of consciousness, possible comedic attack;
• swelling of the organs, cavities, subcutaneous tissue. Body weight is increased due to fluid accumulation.

The stage lasts from several days - an average of 10-14, up to several weeks. The duration of the period and methods of treatment are determined by the severity of the lesion and the nature of the primary disease.

Symptoms of the oligoanuric stage of the arrester

Diagnosis

At this stage, the primary task is to separate anuria from acute urinary retention. For this purpose, the bladder catheter is carried out. If through the catheter all the same no more than 30 ml / hour is output, then the patient has an arrester. To clarify the diagnosis appoint an analysis of creatinine, urea and potassium in the blood.

• With prerenal form, there is a decrease in sodium and chlorine in the urine, the fraction of sodium excretion is less than 1%.With calcium necrosis in the case of an oliguric arthritis, the index increases from 3.5%, while in neoligricheskoy - to 2.3%.
• For differentiation, clarify the ratios of urea in blood and urine, or creatinine in blood and urine. With prerenal form, the ratio of urea to plasma concentration is 20: 1, with renal - 3: 1.For creatinine, the ratio will be similar: 40 in urine and 1 in plasma with prerenal OPN and 15: 1 in renal.
• In renal failure, a characteristic diagnostic feature is a low chlorine content in the blood - less than 95 mmol / l.
• Urine microscopy data allow you to judge the nature of the damage. Thus, the presence of non-protein and erythrocyte cylinders indicates damage to the glomeruli. Brown epithelial cylinders and free epithelium indicate tubular necrosis. Hemoglobin cylinders are detected with intracanulent blockade.

Since the second stage of ARF provokes severe complications, besides urinalysis and blood tests it is necessary to resort to instrumental methods of analysis:

• MRI, ultrasound is performed to detect urinary tract obstruction, size analysis, kidney condition, blood flow assessment. Excretory urography is not performed: radiopaque angiography is prescribed for suspected arterial stenosis;
• chromocystoscopy is prescribed for suspected ureteral obstruction;
• chest X-ray is performed to determine pulmonary edema;
• for the evaluation of renal perfusion appoint isotopic dynamic kidney scans;
• biopsy is performed in those cases when prerenal ARF is excluded, and the origin of the disease is not revealed;
• ECG is assigned to all patients without exception for the detection of arrhythmia and signs of hyperkalemia.

Treatment of OPD

Treatment is determined by the type of OPN - prerenal, renal, postrenal, and degree of damage.

Primary task with prerenal form is restoration of blood supply to the kidney, correction of dehydration and vascular insufficiency.

• In renal form, depending on the etiology, it is necessary to stop taking nephrotoxic drugs and take measures to remove toxins. In systemic diseases, the introduction of glucocorticoids or cytostatics is required as a cause of acute renal failure. When pyelonephritis, infectious diseases, therapy includes antiviral drugs and antibiotics. In the hypercalcemic crisis, intravenously injected large volumes of sodium chloride solution, furosemide, drugs that slow calcium absorption.
• The condition for the treatment of post-acute acute deficiency is the elimination of obstruction.

Correction of water-salt balance is mandatory. Methods depend on the diagnosis:

• for hyperkalemia above 6.5 mmol / l inject calcium gluconate solution, and then glucose. If hyperkalemia is refractory, prescribe hemodialysis;
• for the correction of hypervolemia is administered by furasemide. The dose is selected individually;
• is important to observe the general use of potassium and sodium ions - the value should not exceed daily losses. Therefore, when hyponatremia, the volume of fluid is limited, and when hypernatremia, sodium chloride solution is injected intravenously;
• the volume of liquid - both consumed and injected intravenously as a whole - should exceed losses by 400-500 ml.

When neoliguric form is tried to do without dialysis therapy. But there are a number of indicators for which it is prescribed in any case: symptomatic uremia, hyperkalemia, a severe stage of acidemia, pericarditis, accumulation of a large volume of fluid that can not be withdrawn medically.

Basic principles of treatment of arthritis

Restorative, polyuric

The stage of polyuria appears only with sufficient treatment and is characterized by a gradual restoration of diuresis. At the first stage, the daily volume of urine in 400 ml is recorded, at the stage of polyuria - more than 800 ml.

In this case, the relative density of urine is still low, there are a lot of proteins and red blood cells in the sediment, which indicates the restoration of glomerular function, but indicates damage in the tubular epithelium. In the blood remains a high content of creatinine and urea.

During the treatment the content of potassium is gradually restored, the accumulated liquid is eliminated from the body. This stage is dangerous because it can lead to hypokalemia, which is no less dangerous than hyperkalemia, and can cause dehydration.

The polyuric stage lasts from 2-3 to 10-12 days, depending on the degree of organ damage and is determined by the rate of recovery of the tubular epithelium.

The activities carried out during the oligurical stage continue during recovery. In this case, the doses of drugs are selected and vary individually depending on the indications of the tests. The treatment is carried out against the background of a diet: the intake of protein, liquid, salt and so on is limited.

Recovery stage of OPN

Recovery

At this stage, normal diuresis is restored, and, most importantly, the products of nitrogen metabolism are excreted. If the pathology is severe or the disease is detected too late, the nitrogen compounds may not be completely excreted, and in this case, acute renal failure may change into chronic.

Symptoms of the thermal stage are as follows:

• spasms and muscle cramps;
• internal and subcutaneous hemorrhage;
• cardiac dysfunction;
• sputum discharge with blood, dyspnea and cough caused by accumulation of fluid in the lung tissue;
• loss of consciousness, coma.

Prognosis depends on the severity of the underlying disease. According to statistical data, in the oliguric current, the mortality rate is 50%, while for the neoliguric, it is 26%.If OPN is not complicated by other diseases, then 90% of cases achieve complete recovery of kidney function during the next 6 weeks.

Symptoms of recovery in acute renal failure

Chronic renal failure

CRF develops gradually and represents a decrease in the number of active nephrons - the structural units of the kidney. The disease is classified as chronic if the decrease in functionality is observed for 3 or more months.

In contrast to acute renal failure, chronic and at later stages it is difficult to diagnose, since the disease is asymptomatic, and up to the death of 50% of nephrons, it can be detected only with functional loading.

There are many causes of the disease. However, about 75% of them are glomerulonephritis, arterial hypertension and nephropathy.

Factors significantly increasing the likelihood of CRF include:

• diabetes mellitus;
• smoking;
• obesity;
• systemic infections, as well as ARF;
• infectious diseases of the urinary tract;
• toxic lesions - poisons, drugs, alcohol;
• age changes.

However, for a variety of reasons, the mechanism of damage is almost the same: the number of active nephrons gradually decreases, which provokes the synthesis of angiotensin II.As a result, undamaged nephrons develop hyperfiltration and hypertension. In the parenchyma there is replacement of the renal functional fibrous tissue. Because of the overload of the remaining nephrons, a disruption of the water-salt balance, acid-base, protein, carbohydrate metabolism and so on is gradually developing and developing. In contrast to ARF, the consequences of chronic renal failure are irreversible: it is impossible to replace the dead nephron.

The modern classification of the disease distinguishes 5 stages, which are determined by the rate of glomerular filtration. Another classification is related to the level of creatinine in the blood and urine. This sign is the most characteristic, and it is possible to establish the stage of the disease quite accurately.

The most common classification is associated with the severity of the patient's condition. It allows you to quickly determine what measures must be taken first.

Stages of chronic renal failure

Polyurethane

The polyuric or initial stage of compensation is asymptomatic. Prevalence of signs of primary disease, while the defeat of the kidneys shows little.

• Polyuria - the allocation of too much urine, sometimes exceeding the amount of fluid consumed.
• Nocturia - exceeding the volume of nocturnal diuresis. Normally, urine dissipates at night in less quantity and is more concentrated. The allocation of more urine at night indicates the need for renal and hepatic tests.
• For CRF, even at the initial stage, a decrease in the osmotic density of urine-isostenuria is characteristic. If the density is above 1.018, CRF is not confirmed.
• Arterial hypertension is observed in 40-50% of cases. The difference is that with chronic renal failure and other kidney diseases, AD has little effect on conventional antihypertensive drugs.
• Hypokalemia can occur at the stage of polyuria with an overdose of saluretics. It is characterized by a strong muscle weakness, changes in the ECG.

Diagnosis includes the analysis of urine and blood. The most revealing of them include the evaluation of creatinine in the blood and urine.

The glomerular filtration rate is also a good determining factor. However, in the polyuric stage this value is either normal - more than 90 ml / min or slightly reduced - up to 69 ml / min.

At the initial stage, treatment is mainly aimed at suppressing the primary disease. It is very important to follow a diet with a restriction on the number and origin of protein, and, of course, the use of salt.

Symptoms of the polyuric phase of chronic renal failure

Stage of clinical manifestations of

This stage, also known as azotemic or oligoanus, is characterized by specific abnormalities in the body, indicating significant damage to the kidneys:

• The most characteristic symptom is a change in the volume of urine. If the first stage of the fluid was more than normal, then in the second stage of CRF, the volume of urine becomes less. Oligouria develops -500 ml of urine per day, or anuria - 50 ml of urine per day.
• There are signs of intoxication - vomiting, diarrhea, nausea, the skin becomes pale, dry, at later stages it acquires a characteristic icteric hue. Because of the deposition of urea, patients are disturbed by severe itching, combed skin practically does not heal.
• There is severe weakness, weight loss, lack of appetite until anorexia.
• Due to the violation of the nitrogen balance, a specific "ammonia" odor from the mouth appears.
• At a later stage, renal puffiness is formed, first on the face, then on the limbs and on the trunk.
• Intoxication and high blood pressure cause dizziness, headaches, memory disorder.
• There is a feeling of chills in the hands and feet - first in the legs, then decreases their sensitivity. Movement disorders are possible.

These external signs indicate the adherence to CRF of concomitant diseases and conditions caused by renal dysfunction:

• Azotemia - occurs when an increase in the products of nitrogen metabolism in the blood. Determined by the amount of creatinine in the plasma. The uric acid content is not so indicative, as its concentration increases for other reasons.
• Hyperchloremic acidosis - due to a violation of the mechanism of calcium absorption and is very characteristic for the stage of clinical manifestations, increases hyperkalemia and hypercatabolism. Its external manifestation is the appearance of shortness of breath and great weakness.
• Hyperkalemia is the most frequent and most dangerous symptom of CRF.The kidney is able to maintain the potassium absorption function up to the terminal stage. However, hyperkalemia depends not only on the functioning of the kidney and, if damaged, develops at the initial stages. With an excessively high potassium content in the plasma - more than 7 meq / l, the nerve and muscle cells lose their ability to excitability, which leads to paralysis, bradycardia, CNS damage, acute respiratory failure, and so on.
• With a decrease in appetite and against intoxication, a spontaneous decrease in protein intake occurs. However, its too low content in food for patients with CRF is no less harmful, as it leads to hypercatabolism and hypoalbuminemia - a decrease in albumin in the blood serum.

Another characteristic feature for patients with chronic renal failure is overdose of drugs. With CRF, the side effects of any drug are much more pronounced, and an overdose occurs in the most unexpected cases. This is due to dysfunction of the kidney, which is not able to remove the decay products, which leads to their accumulation in the blood.

Diagnosis

The main purpose of the diagnosis is to distinguish CRF from other renal ailments with similar symptoms and in particular from acute form. To do this, resort to various methods.

From the analysis of blood and urine the following indicators are the most informative:

• the amount of creatinine in the blood plasma is more than 0.132 mmol / l;
• glomerular filtration rate - a pronounced decrease is a value of 30-44 ml / min. At a rate of 20 ml / min, urgent hospitalization is necessary;
• urea in the blood - more than 8,3 mmol / l. If the increase in concentration is observed against the background of a normal creatinine content, the ailment is likely to have a different origin.

From instrumental methods resort to ultrasound and X-ray methods. A characteristic feature of CRF is a decrease and shrinkage of the kidney, if this symptom is not observed, a biopsy is shown.

Rentgen-contrast test methods are not allowed

Treatment of

Until the terminal stage, treatment of CRF does not include dialysis. Conservative treatment is prescribed depending on the degree of damage to the kidneys and related disorders.

It is very important to continue treatment of the underlying disease, while excluding nephrotoxic drugs:

• A small part of the treatment is a low protein diet - 0,8-0,5 g /( kg * day).If the serum albumin content is less than 30 g / l, the restriction is weakened, since at such a low protein content it is possible to develop a nitrogen imbalance, the addition of keto acids and essential amino acids is shown.
• With GFR scores around 25-30 ml / min, thiazide diuretics are not used. At lower values, they are assigned individually.
• For chronic hyperkalemia, ion-exchange polystyrene resins are used, sometimes in combination with sorbents. In acute cases, calcium salts are administered, hemodialysis is prescribed.
• Corrections of metabolic acidosis are achieved by adding 20-30 mmol of sodium bicarbonate - intravenously.
• For hyperphosphatemia, substances that interfere with the absorption of phosphate by the intestine are used: calcium carbonate, aluminum hydroxide, ketosteril, phosphocytrylic. With hypocalcemia, calcium preparations - carbonate or gluconate - are added to the therapy.

Stage of decompensation of

This stage is characterized by worsening of the patient's condition and appearance of complications. The glomerular filtration rate is 15-22 ml / min.

• Headache and lethargy is accompanied by insomnia or, conversely, severe drowsiness. The ability to concentrate attention is disturbed, confusion of consciousness is possible.
• Progresses peripheral neuropathy - loss of sensitivity of the hands and feet until immobilization. Without hemodialysis, this problem is not solved.
• The development of gastric ulcer, the appearance of gastritis.
• Often CPN is accompanied by the development of stomatitis and gingivitis - inflammation of the gums.
• One of the most serious complications of chronic renal failure is inflammation of the serosa of the heart - pericarditis. It is worth noting that with adequate treatment this complication is rare. Lesions of the myocardium on the background of hyperkalemia or hyperparathyroidism is observed much more often. The degree of defeat of the cardiovascular system is determined by the degree of arterial hypertension.
• Another frequent complication is pleurisy, that is, inflammation of the pleura.
• With fluid retention, stagnation of the blood in the lungs and swelling of them are possible. But, as a rule, this complication appears already at the stage of uremia. Detect the complication of the X-ray method.

Treatment is correlated depending on the complications. Perhaps a connection to conservative hemodialysis therapy.

In the absence of treatment, the stage of decompensation passes to the terminal stage. In this case, one can save the life of the patient only by resorting to kidney transplantation or hemodialysis.

Terminal

Terminal( last) stage - uremic or anuric. Against the backdrop of delayed products of nitrogen metabolism and disturbance of water-salt, osmotic homeostasis, etc., auto-toxication develops. Dystrophy of body tissues and dysfunction of all organs and systems of the body are recorded.

• Symptoms of loss of sensitivity of the limbs, followed by complete numbness and paresis.
• The probability of uremic coma and cerebral edema is high. Against the background of diabetes mellitus hyperglycemic coma is formed.
• In the terminal stage, pericarditis is a complication more frequent and causes death in 3-4% of cases.
• Lesions of the digestive tract - anorexia, glossitis, frequent diarrhea. Each 10 patients have gastric bleeding, which is the cause of death in more than 50% of cases.

Conservative treatment at the terminal stage is powerless.

Depending on the general condition of the patient and the nature of the complications, more effective methods are used:

• Hemodialysis - purification of blood with the aid of the "artificial kidney" apparatus. The procedure is carried out several times a week or every day, has a different duration - the regime is selected by the doctor in accordance with the patient's condition and dynamics of development. The apparatus performs the function of the deceased organ, so without it patients with a diagnosis can not live.

Hemodialysis for today is a more accessible and more effective procedure. According to data for Europe and the United States, the life expectancy of such a patient is 10-14 years. There are cases when the forecast is most favorable, since hemodialysis prolongs life by more than 20 years.

• Peritoneal dialysis - in this case, the role of the kidney, and, more accurately, of the filter, performs the peritoneum. The liquid introduced into the peritoneum absorbs the products of nitrogen metabolism, and then is withdrawn from the stomach to the outside. This procedure is performed several times a day, since its effectiveness is lower than that of hemodialysis.
• Kidney transplantation is the most effective method, however, it has a lot of limitations: peptic ulcer, mental illness, endocrine disorders. It is possible to transplant the kidney from both the donor and the cadaver.

Recovery after surgery lasts at least 20-40 days and requires the most careful adherence to the prescribed regimen and treatment. A kidney transplant can prolong a patient's life by more than 20 years, if complications do not appear.

Stages of creatinine and the degree of reduction of glomerular filtration

The concentration of creatinine in urine and blood is one of the most characteristic distinctive features of chronic renal failure. Another very "talking" characteristic of a damaged kidney is the rate of glomerular filtration. These signs are so important and informative that classification of chronic renal failure by creatinine or by GFR is more common than traditional.

Classification by creatinine

Creatinine is the product of the breakdown of creatine phosphate, the main source of energy in muscles. When the muscle contractes, the substance breaks down into creatinine and phosphate with the release of energy. Creatinine then enters the bloodstream and is excreted by the kidneys. The average norm for an adult is a substance with a blood content of 0.14 mmol / l.

Increased creatinine in the blood and provides azotemia - the accumulation of products of nitrogen decomposition.

The concentration of this substance is divided into 3 stages of the development of the disease:

• Latent - or reversible. The level of creatinine varies from 0.14 to 0.71 mmol / l. At this stage, the first uncharacteristic signs of CRF appear and develop: lethargy, polyuria, a slight increase in blood pressure. There is a decrease in the size of the kidney. The picture is typical for a state where up to 50% of nephrons die.
• Azotemic - or stable. The level of the substance varies from 0.72 to 1.24 mmol / l. It coincides with the stage of clinical manifestations. Developing oliguria, there are headaches, shortness of breath, swelling, muscle spasms and so on. The number of working nephrons is reduced from 50 to 20%.
• uremic stage - or progressive. It is characterized by an increase in creatinine concentration above 1.25 mmol / l. Clinical signs are pronounced, complications develop. The number of nephrons decreases to 5%.

On the glomerular filtration rate

The glomerular filtration rate is a parameter by which the excretory capacity of an organ is determined. It is calculated in several ways, but the most common involves the collection of urine in the form of two hourly portions, the determination of minute urine output and the concentration of creatinine. The ratio of these indicators and gives the value of glomerular filtration.

The classification according to GFR includes 5 stages:

• 1-stage at a normal level of GFR, that is, more than 90 ml / min, there are signs of kidney pathology. At this stage, for curing, it is sometimes enough to eliminate the existing negative factors - smoking, for example;
• 2 stage - easy reduction of GFR - from 89 to 60 ml / min. And for 1 and 2 stages it is necessary to follow a diet, accessible physical activity and periodic observation by a doctor;
• 3A stage - a moderate decrease in the rate of filtration - from 59 to 49 ml / min;
• 3B stage - marked decrease to 30 ml / min. At this stage, drug treatment is performed.
• Stage 4 - characterized by a heavy decrease - from 29 to 15 ml / min. There are complications.
• 5 stage - GFR is less than 15 ml, the stage corresponds to uremia. The state is critical.

KPN stages for glomerular filtration rate

Renal failure is a serious and very insidious syndrome. In chronic course, the first signs of damage to which the patient pays attention only appear when 50% of nephrons die, that is, half of the kidneys. In the absence of treatment, the likelihood of a favorable outcome is extremely low.