Renal agenesis is the absence of embryoanal development of one or both renal anlagen. Unilateral renal agenesias are usually asymptomatic and do not affect life, whereas bilateral forms are usually lethal. In bilateral agenesis, renal transplantation is the only effective therapy.
What is renal agenesis?
During embryogenesis, kidneys develop piecemeal on a healthy embryo. This development occurs on the basis of the intermediate mesoderm and involves the separate creation of the pre-kidneys, primordial kidneys, and post-kidneys. The individual developmental steps are highly complex. In early embryonic development, three kidneys are laid down in succession. The last one to be formed takes over the kidney function, while the two other kidneys regress or are incorporated into the urogenital tract. Development continues from the 22nd day of pregnancy until approximately the fifth week of gestation. If a defect occurs during fetal kidney development, it can cause renal agenesis. In such a renal agenesis, development of one or even both kidneys fails to occur. If only one kidney is affected, the medical profession refers to it as unilateral renal agenesis. If both kidneys are affected, the condition is called bilateral renal agenesis. Sometimes this is also referred to as anephria, which is usually lethal.
Causes
The causes of renal agenesis lie in embryogenesis. The renal anlagen are either defectively differentiated or not differentiated at all by the fifth week of gestation. Renal agenesis has been found in about one in 800 to 1100 live births to date. Boys were more frequently affected than girls. A familial clustering could not be found. Presumably, therefore, no genetic dispositions are associated with the phenomenon. Thus, renal agenesis probably cannot be passed on. Instead of genetic causes, the lack of formation of one or both kidneys is due to a maldevelopment of the primitive ureter. The metanephrogenic blastema of the affected individuals is also affected by a maldevelopment, which is equally causally related to the agenesis. The cause of the ureteral and blastemal maldevelopment has not been conclusively clarified. Spontaneous gene mutations caused by environmental toxins are currently speculated.
Symptoms, complaints, and signs
Unilateral absence of the kidneys is still compensated during renal development usually by the enlarged anlage of the second kidney. Thus, clinically, unilaterally absent kidney anlagen need not present with any symptoms as long as the second kidney is fully functional. Concomitant malformations of the urinary organs occur, such as those of the bladder as well as the ureter. Under certain circumstances, recurrent urinary tract infections may occur, with which the malformations are causally related. Bilateral renal agenesis is also usually associated with other malformations. Because the malformations in this form of agenesis often correspond to multiple malformations of the lungs, for example, and because without kidneys the waste products cannot be removed from the blood in the long term even with the help of dialysis, bilateral agenesis of the kidneys is generally not compatible with life. Symptoms of intoxication are present in addition to deficiencies of vitamins and erythropoietins.
Diagnosis and course of the disease
Diagnosis of renal agenesis is usually made prenatally on the basis of sonography. If the unilateral maldevelopment is detected only postnatally, it is usually an incidental sonographic finding because patients are asymptomatic. Urine and serum tests can be used to assess renal function. This requires determination of creatinine and urea levels as well as electrolyte levels. For the electrolyte level, potassium, sodium and chlorine play a primary role. Unilateral renal agenesis is usually asymptomatic and hardly affects the patient. Bilateral forms of renal agenesis are associated with a lethal prognosis.
Complications
Unilateral renal agenesis, as mentioned above, usually causes no symptoms because one kidney performs the functions of both kidneys. However, the risk of complications is increased if urinary tract disease occurs. If both kidneys are missing, survival is not possible at all.Often, the absence of a kidney is not even noticed by the affected person. However, in female patients, a malformation of the genitals is observed in 75 to 90 percent of cases. If a unilateral renal agenesis is diagnosed due to an incidental finding, constant medical monitoring is nevertheless necessary in order to rule out complications in advance. Threatening are always the diseases that could cause a loss of kidney function. Often, this leads to the patient’s need for dialysis up to total kidney failure, which can then only be treated with the help of a kidney transplant. Therefore, patients with unilateral renal agenesis need to monitor themselves for symptoms and take measures to prevent diseases of the urinary tract. This requires appropriate hygiene measures such as urinating after coitus or, in women, wiping the urethral outlet toward the anus. If there are signs of a urinary tract infection, an immediate blood and urine test is required. The same applies if there is an unclear febrile infection. An infection of the urinary tract must be treated immediately with antibiotics.
When should you go to the doctor?
Parents whose child has been diagnosed with renal agenesis must have close consultation with their doctor. The absence of one or both kidneys is a serious condition that must be treated as part of an organ transplant. Accordingly, affected children cannot leave the hospital after birth, but must be closely monitored and cared for. After surgery, the child should be carefully observed. Any signs that the body is rejecting the donor kidney should be reported immediately to the attending physician. The child must be taken to a clinic immediately so that further investigations and, if necessary, a new operation can be initiated. In the case of unilateral renal agenesis, a physician should be consulted if the child shows signs of severe malaise. In case of inflammation of the urinary tract as well as abdominal injuries, immediate clarification by a specialist is required, as there is a risk of inflammatory kidney damage. In addition to the general practitioner, both forms of renal agenesis are treated by an internist. Accompanying therapeutic support should be sought by parents and child.
Treatment and therapy
Complete anephria can be corrected only by organ transplantation. Unilateral renal agenesis usually does not require treatment because the enlarged, second kidney satisfactorily replaces the function of the missing kidney. Complications include concomitant diseases that affect the function of the remaining kidney. Functional kidney diseases, for example, make patients with unilateral renal agenesis in need of dialysis and become life-threatening more quickly for those affected than for people without a missing kidney. For this reason, all diseases of the urinary tract, as well as abdominal injuries, must be observed with caution and circumspection to prevent functional renal disease. Those affected by unilateral renal agenesis are therefore urged by the physician to observe themselves carefully if, for example, they become ill with inflammation of the draining urinary tract, since such inflammation can lead to inflammatory kidney damage. Hygiene measures for the prophylaxis of urinary tract infections are crucial preventive measures by which patients can protect their remaining kidney. As soon as the first signs of a urinary tract infection or another infection of unclear origin appear, patients with renal agenesis must have these symptoms clarified immediately by a physician via blood analyses and urine samples before their unilateral kidney can be damaged. Antibiotic therapy must be given as soon as possible for inflammatory diseases of the urinary tract.
Outlook and prognosis
The prognosis of renal agenesis depends on the extent of individual symptoms. Crucial for the further course is clarification of whether one or both kidneys are affected by the health disorders. In a large number of those affected, a diagnosis is already made in the womb. Doctors can therefore react to possible complaints in good time and comprehensively, as they are prepared for health irregularities. In the event of an unfavorable course of the disease, both of the patient’s kidneys are affected.There is a need for kidney transplantation in these cases. The transplantation of a donor organ is associated with numerous complications and side effects. Lifelong medical care takes place so that immediate action can be taken in the event of symptoms. In some patients the disease remains undetected for a long time. The existing complaints are slight in them or the affected person experiences freedom from complaints. This is often the case when the renal agenesis affects only one kidney. In this case, the healthy kidney takes over the tasks for both organs, so that often no impairments are noticed in everyday life. In principle, the risk of infection is increased in people with the disease. If complications or further illnesses occur, there is a risk of organ failure. Once the kidney’s ability to function is impaired, a life-threatening condition develops.
Prevention
The causes of renal agenesis are unknown to date. Therefore, it is difficult to prevent this maldevelopment of the kidneys. Since genetic mutations due to environmental toxins are now associated with the malformation, avoidance of toxic contacts may be a preventive measure. Environmental toxins, on the other hand, cannot be completely avoided during pregnancy under any circumstances.
Follow-up
In most cases, the person affected by renal agenesis has very few and also very limited measures or options for direct aftercare. Affected individuals should therefore contact a physician at the first symptoms or signs of the condition to avoid further complications or discomfort. Self-cure of renal agenesis cannot occur. This disease does not always need to be treated, although regular checks and examinations by a doctor are very important. Especially the kidneys and the urinary tract should be checked regularly by a doctor. Likewise, regular blood analyses should be performed. In some cases, renal agenesis can lead to infections or inflammations of the urinary tract or kidneys, so that treatment with antibiotics is necessary. Affected persons should always observe the correct dosage and also regular intake, and alcohol should be avoided during the course of treatment. In general, a healthy lifestyle with a healthy diet can have a very positive effect on the further course of the disease. As a rule, this disease does not reduce the life expectancy of those affected.
This is what you can do yourself
Unilateral renal agenesis does not require treatment. The child can grow up with one kidney without any problems or complications. Nevertheless, parents should watch for unusual symptoms and report them to the doctor if necessary. However, if there are any symptoms that indicate kidney dysfunction, emergency medical services must be contacted. In the case of bilateral renal agenesis, the child is not viable without dialysis. The most important self-help measure is to work through the fears associated with such a severe condition. After a kidney transplant, the child must be under constant observation so that the emergency physician can be called immediately in case of complications. Parents can also arrange for outpatient care to assist them in caring for the child. Accompanying symptomatic treatment, parents should visit a specialist center for internal diseases to learn more about renal aganesia. In general, knowledge about the disease helps to take the right measures in case of emergency. As the child grows up, he must be educated about his condition. Parents can take on this task themselves and inform the child about the disease together with the responsible nephrologist or family doctor.
