Aminoaciduria refers to a number of diseases and metabolic disorders that result in the excretion of amino acids through the final urine. In most cases, this is hyperaminoaciduria, in which more than 5 percent of the amino acids that have been filtered through the renal corpuscles into the primary urine are not reabsorbed and therefore can be detected in the final urine. Aminoaciduria is an important symptom in several renal and metabolic diseases that are inherited or acquired.
What is aminoaciduria?
Aminoaciduria is an important symptom in several kidney and metabolic diseases that are inherited or acquired. Aminoaciduria is the excretion of amino acids through the final urine. Because even healthy people excrete up to five percent of amino acids that have been filtered into the primary urine, aminoaciduria is often equated with hyperaminoaciduria, in which more than five percent of amino acids are not reabsorbed but excreted in the final urine. The excretion of amino acids via the final urine is an expression and symptom of several different metabolic disorders. It is primary aminoaciduria if it is a genetic form of the disease and secondary aminoaciduria if the metabolic disorder is acquired. Impaired reabsorption may generally refer to all amino acids collected in the primary urine. However, it is also possible that specific amino acids are affected, as in cystinuria, in which only the dibasic amino acids ornithine, arginine, lysine, and cystine are affected. Aminoaciduria lasting only a short time may be nutritional due to excessive intake of proteins. This is a natural form of aminoaciduria that will self-adjust.
Causes
Several factors are known to cause aminoaciduria and hyperaminoaciduria, respectively. Most are genetically determined metabolic disorders, each leading to one of the inherited forms of aminoaciduria. For example, autosomal recessive cystinuria is caused by a defectively encoded transmembrane transport protein. The special transport protein normally ensures the passage of the amino acid cystine and the other dibasic amino acids through the membranes of the tubule cells in the epithelial cells of the proximal tubule cells of the kidney, which corresponds to classical reabsorption. The rare hereditary fructose intolerance, another form of aminoaciduria, is also inherited in an autosomal recessive manner. A genetic defect causes a deficiency of aldolase B in the liver, which leads to glycolysis being inhibited when fructose accumulates. Ultimately, this causes an intracellular deficiency of ATP, resulting in severe hypoglycemia (low blood sugar). The disease is accompanied by several symptoms, among which aminoaciduria is typically seen. There are other known inherited metabolic diseases in which aminoaciduria is a leading symptom. Causes may involve a transport protein for a particular class of amino acids or a required enzyme that is defectively encoded due to a genetic defect, rendering it nonfunctional. In some cases, interstitial nephritis or liver dysfunction also causes aminoaciduria.
Symptoms, complaints, and signs
The symptoms and complaints that accompany aminoaciduria vary and depend on the causative factors and thus on the metabolic processes involved. For example, inherited cystinuria is manifested by precipitation of the unabsorbed amino acid cystine in the urine, which tends to form urinary stones. About 50 percent of those affected develop urinary stones. In the rare inherited fructose intolerance, symptoms occur only after ingestion of fructose. However, symptoms can also occur after eating “normal” sucrose because the body breaks down the disaccharide into glucose and fructose. Typical symptoms include nausea, vomiting, sweating, and aminoaciduria.
Diagnosis and course
General aminoaciduria can be detected by determining the concentration of amino acids in the final urine. If only certain amino acids are found in the urine, the finding facilitates further diagnosis.It is then usually one of the inherited metabolic disorders such as cystinuria, in which there is an accumulation of the amino acids cystine, ornithine, arginine and lysine in the urine. The disease cannot be cured, but the further course can be influenced with a lot of fluid intake, so that the formation of urinary stones is prevented as far as possible. The course of the disease depends on the causes and on the behavior of the affected person.
Complications
The complications and symptoms of aminoaciduria are very varied and for this reason cannot be assessed in general terms. However, there is always a disturbance of the metabolic processes. In many cases, this disturbance leads to the formation of urinary stones, for example. Due to the urinary stones, the patient suffers from very severe pain and unpleasant feelings. Everyday life is extremely restricted by the aminoaciduria, and it is usually no longer possible to pursue an activity. In addition, vomiting, panic attacks or nausea with dizziness often occur. Aminoaciduria can also lead to the development of various allergies that were not previously present in the patient. The formation and treatment of urinary stones can be relatively well influenced by an increased intake of fluids. In this case, the patient must also try to maintain a healthy diet and lifestyle. If an intolerance to fructose develops in the case of aminoaciduria, the affected person must abstain from it for the rest of his life. In this case there is no possibility of treatment. Life expectancy is usually barely reduced, but depends greatly on the patient’s lifestyle.
When should one go to the doctor?
Usually, aminoaciduria points to diseases of the kidneys or urinary tract. In any case, these diseases should be investigated and, if necessary, also treated and removed by the doctor. In most cases, aminoaciduria results in the formation of a urinary stone. This is associated with extremely severe pain in the patient, with urination in particular being significantly affected. For this reason, treatment must then be given if there is suddenly considerable pain in the area of the kidneys and ureters. It is not uncommon for patients to also suffer from sweating, dizziness or vomiting. These complaints can also indicate aminoaciduria. If the complaints occur after the consumption of fructose, this intolerance must be determined by a physician. In this case, the patient must abstain from the ingredient. Treatment can generally begin with a general practitioner if the individual is unsure of the symptoms or cannot accurately attribute them to a disease. In case of acute pain, an ambulance should be called or the hospital should be visited.
Treatment and therapy
Aminoacidurias that are due to genetically determined malfunctions of transport proteins or enzymes cannot be treated causally. The urgent goal in such disorders is to minimize the effects of aminoaciduria. In the case of cystinuria mentioned above, a daily fluid intake of up to four liters is required to prevent urinary stones. The high fluid intake virtually dilutes the urine so that the poorly soluble cystine does not precipitate. In the case of fructose intolerance, only lifelong avoidance of fructose and sucrose is effective. If aminoaciduria is caused by interstitial nephritis or by functional impairment of the liver, possible therapy is aimed primarily at treating the underlying disease. Aminoaciduria resolves on its own after the inflammation of the kidney (nephritis) has healed.
Outlook and prognosis
Aminoaciduria may cause various symptoms and complications in the affected person. The further course of this disease is highly dependent on other environmental factors, so that a general prediction is usually not possible. However, aminoaciduria can lead to the formation of urinary stones. These are associated with very severe pain and significantly limit the patient’s quality of life. Furthermore, vomiting or nausea may also occur. Those affected often also suffer from sweating and are thus significantly restricted in their daily lives. Aminoaciduria can also lead to the development of various allergies or intolerances.Likewise, fructose intolerance can occur in some cases, so that the affected person must do without this ingredient for the rest of his or her life. Unfortunately, it is not possible to treat aminoaciduria causally. For this reason, the main thing is to limit the effects and symptoms of this disease as much as possible. Above all, kidney stones can be avoided by increasing fluid intake. Whether life expectancy is reduced by aminoaciduria cannot be generally predicted.
Prevention
Any form of aminoaciduria is always the effect of a primary disease or defect, such as defectively encoded transport proteins or enzymes. Direct preventive measures that could prevent aminoaciduria therefore do not exist. In principle, preventive measures would therefore have to be aimed at preventing the associated primary diseases or defects. However, this is not possible for most primary diseases because they are genetically determined primary defects. In principle, behaviors that prevent renal inflammation and diseases of the liver are useful.
Follow-up
In most cases, aminoaciduria indicates another inherited disease, so the focus is on treating the underlying disease. However, whether this will result in a complete cure cannot generally be predicted. In some cases, those affected are also dependent on lifelong therapy to alleviate the symptoms. Options for aftercare are therefore very limited for those affected by aminoaciduria. In general, a healthy lifestyle with a healthy diet has a positive effect on the course of the disease. At the same time, the trigger for the aminoaciduria must also be found and further avoided. In some cases, this may require the patient to avoid certain foods and ingredients in order to keep symptoms to a minimum. To avoid the formation of kidney stones, extra fluids should be taken. It is possible that aminoaciduria may also reduce the patient’s life expectancy. Foods that have an increased content of fructose should be avoided at all costs. In the case of aminoaciduria, contact with other sufferers of the condition may also prove useful, as this can lead to an exchange of information.
Here’s what you can do yourself
Aminoaciduria must be diagnosed and treated by a physician. Accompanying medical therapy, the symptoms can be alleviated by some home remedies and self-help measures. First of all, the diet should be changed: Foods containing fructose and sucrose (juices, oranges and lemons, lentils, cane sugar, shortbread) are best avoided, while foods rich in amino acids (meat, fish, dairy products, eggs, cottage cheese, nuts) should be consumed more frequently. In consultation with the doctor, the diet can be supplemented with food supplements containing amino acids. In addition, a lot should be drunk. On the one hand, this promotes metabolism and thus digestive activity. On the other hand, urinary stones and other typical secondary symptoms of aminoaciduria are prevented. Home remedies such as kombucha, corn tea or warm beer are also recommended against kidney gravel. Proven remedies from nature include dried sea thistle roots, marshmallow leaves or birch leaf tea. Various home remedies and medicinal plants also alleviate accompanying symptoms such as nausea, vomiting and sweating. Which remedies and preparations are useful in detail should be clarified with the doctor beforehand. Lastly, a healthy lifestyle with plenty of exercise and sufficient sleep should be maintained to accelerate the healing process.
