In nephrology, medullary kidney refers to a cystic medullary kidney disease that affects the renal medulla. Although the disease is present from birth, it sometimes remains asymptomatic throughout life. Possible symptoms include urinary calculi and kidney stones in the form of calcium deposits.
What is medullary sponge kidney?
Marrow sponge kidney is a cystic kidney disease. From birth, both or, less commonly, only one of the kidneys have cystic changes in the medullary pyramids and papillae in the renal medulla, which are connected to the collecting tubes of the kidneys. The renal medulla and its pyramid are impaired in their ability to concentrate urine due to the cystic enlargements. Thus, the kidneys of affected individuals often excrete too little acid or too much calcium and form kidney stones. Urinary stones can also develop. In extreme cases, renal tubular acidosis develops. Although medullary sponge kidney is congenital, it is not considered a hereditary kidney disease. To be distinguished from the disease are thus:
- The cystic medullary kidney diseases type I and II.
- The nephronophthisis, which are largely genetic.
For symptomatic medullary sponge kidney, the prevalence is reported to be 1:5000 to 1:20000. For asymptomatic medullary sponge kidney, the prevalence is 1:200.
Causes
Marrow sponge kidney disease usually occurs spontaneously. The original cause of the cystic changes is as yet unknown. No specific gene or chromosomal mutations have been associated with the disease. The transmission of the disease appears to be unpredictable. Because of the unpredictability, scientists believe that instead of a genetic basis, a complication in pregnancy is the more likely cause of the disease. A combination of genetic and environmental factors is also being considered. If such a combination is present, autosomal dominant inheritance is suspected for the genetic factors. Even if the susceptibility is hereditary in the sense of a genetic disposition, in this case the disease breaks out exclusively when the affected person comes into contact with the environmental factors.
Symptoms, complaints, and signs
Congenitally, in medullary sponge kidney, cystic enlargements are prominent in one or both kidneys. The entire renal medulla need not be affected by the cysts. Localized changes also occur. Cystic dilatation occurs primarily in the terminal collecting tubes of the renal medulla. Often, cysts also form in the tips of the papillae. The cysts contain calcium oxalate concretions. Although the kidneys of affected individuals retain their physiologic shape, they have a spongy appearance. In most cases, they are also enlarged. The cysts create obstructions that alter the parenchyma. Renal insufficiency does not usually occur. Medullary sponge kidney usually remains asymptomatic for a long time. In fact, about half of those affected remain asymptomatic for the rest of their lives. If symptoms occur at all, they are usually urinary and renal stones, recurrent renal colic, urinary tract infections or hematuria.
Diagnosis and course of the disease
Medullary sponge kidney is diagnosed by radiographic imaging. Pyelography may also be used to confirm the diagnosis. In this procedure, the papillary cavities of the kidneys fill first rather than the renal calices. Although the changes are congenital, diagnosis is usually late. In most cases, a diagnosis is not expected until young adulthood and then usually corresponds to an incidental finding. In many cases, the diagnosis is also not made until the fifth decade of life or even after death. The prognosis is relatively favorable. For example, a reduced life expectancy does not apply to medullary sponge kidney. Although kidney and urinary calcium stones can cause severe pain and thus reduce the quality of life, they can just as easily remain silent. Thus, the extent of suffering in the setting of medullary sponge kidney depends on the individual case.
Complications
Medullary sponge kidney causes cysts to form in and around the kidneys. These enlarge as a result and there is no self-healing. Sometimes, in the worst case, renal insufficiency can occur, which without treatment can also lead to the death of the patient.The affected person is then dependent on a donor kidney or dialysis in order to continue to survive. However, the medullary sponge kidney does not necessarily lead to complications or complaints in every case, so that many patients live their entire lives with the medullary sponge kidney without any restrictions or complaints. However, the formation of kidney stones or urinary calculi can increase. Further infections of the kidneys or urinary tract are also possible. The symptoms of medullary sponge kidney can be relatively well limited by increased fluid intake and various therapies. Complications usually do not occur. However, it is not uncommon for patients to be dependent on taking medication. With successful treatment, the patient’s life expectancy is not reduced and no further complications occur.
When should you see a doctor?
With medullary sponge kidney, most patients do not experience any symptoms or irregularities. This results in some cases not being diagnosed during life. Every person should participate in the regularly offered control and routine examinations even if they are free of symptoms. These take place in the first years of life and are offered to adults from the age of 35. The need to consult a doctor also arises as soon as the person concerned notices irregularities or complaints in the area of the kidneys. A doctor should be consulted in the event of altered kidney activity or a diffuse feeling. If there are problems with urination, blood in the urine, abnormalities in fluid intake or if ulcers can be felt in the kidney area, a doctor should be consulted. Swelling or a feeling of pressure in the upper body are indications of existing cysts, which should be clarified by a doctor. A persistent urge to urinate immediately after going to the toilet, repeated infections of the urinary tract or the formation of urinary and kidney stones indicate the presence of a medullary sponge kidney. If colic occurs, a physician must be consulted as soon as possible. Because there is a risk of organ failure, emergency medical services should be alerted immediately in the event of spasms and severe pain in the kidneys.
Treatment and therapy
Causative treatment is not yet available for medullary sponge kidney disease. Thus, therapy is exclusively symptomatic. Both drug therapies and surgery can take place as symptomatic treatment. Especially in cases of stone disease in the urinary tract or kidneys, stone disintegration is performed. For smaller stones, the disintegration is done by shock waves. Without any surgery or anesthesia, shock wave devices transmit shocks to the tissue water, which shatter the concretions of calcium. The patient excretes the shattered stones in the urine. Larger concretions cannot be removed in this way. Even with a large number of stones, surgical removal is the treatment of choice. To prevent stone formation or to reduce the risk of recurrence after disintegration, patients of medullary sponge kidney should drink as much water as possible. Drinking 2.5 liters per day is considered a minimum. However, stone formation can also be prevented by drug treatments. To combat hypercalciuria and as a prophylaxis for nephrolithiasis, for example, patients are given thiazides, which also reduce the risk of urinary and kidney stones. Urinary tract infections are usually countered with antibiotic therapy.
Outlook and prognosis
The prognosis of medullary sponge kidney is based on the individual manifestation of the disease. Nevertheless, spontaneous healing is not to be expected. Cysts form on the kidney that require medical attention. Otherwise, there is a risk of the disease spreading and thus an increase in health impairments. In the case of a very unfavorable course of the disease and an intensive manifestation of the genetic disease, the affected person may also die prematurely. The functional activity of the kidney is limited due to the tissue neoplasms. If no timely medical treatment takes place, irreversible damage to the organ may occur. In addition, a failure of the organ activity is possible. In these cases, a life-threatening disorder is present. The affected person is threatened with premature death.If medical care is initiated at the first irregularities in tissue formation, symptoms can often be completely cured. A disintegration of the cysts or stones is initiated. Subsequently, the foreign bodies are transported away by the organism and excreted. In addition, surgical interventions can be performed, which also pursue the removal of the foreign bodies. With this treatment method, the risk of complications is increased. Nevertheless, it often represents the only prospect of recovery. In the further course of life, new formation of the foreign bodies can occur at any time.
Prevention
So far, medullary sponge kidney cannot be prevented, as the causes of the disease have not been conclusively clarified. Nonetheless, risk for discomfort can be reduced, for example, by ensuring that those affected consume sufficient fluids.
Aftercare
Because the disease as well as the treatment of medullary sponge kidney are relatively complex, the aftercare applies to trying to find a good way to deal with the situation. This can lead to psychological upsets, which should sometimes be clarified by a psychologist. Therapy or contact with others affected can help to better accept the disease. This can increase well-being, regardless of the fact that treatment continues. Medullary sponge kidney can lead to various complications and discomfort in the patient if it is not treated. Affected individuals should see their treating physician on a regular basis and strictly adhere to instructions for their own sake. This also includes the diet, which should relieve the kidneys during regeneration. In this respect, aftercare is aimed at adjusting to the unfamiliar situation and promoting a healthy lifestyle. The further course of the disease depends very much on its severity, so that a general prediction is usually not possible. In some cases, the life expectancy of the patient is also limited.
What you can do yourself
If symptoms of kidney disease appear, a doctor should be consulted first. Medullary sponge kidney can be treated symptomatically by those affected, but this requires a comprehensive assessment by a physician. Accompanying drug therapy, which serves to reduce pain, a strict diet must be followed. A lot of fluids should be consumed (at least three liters daily), especially before bedtime and after meals. The daily diet should consist mainly of sparing food. Depending on the severity of the medullary sponge kidney, foods such as vegetables, fruits and low-salt foods are recommended. Meat and sausage should be avoided as far as possible. Coffee and alcohol should also be avoided, as they represent an additional burden for the kidneys. In general, attention must be paid to an intact intestinal flora. In consultation with the doctor, a purification or fasting cure can be carried out to strengthen the health of the intestines and kidneys. General measures such as sports and the avoidance of stress have a positive effect on the entire body and thus also on the diseased kidney. If the complaints increase despite all measures, it is best to talk again with the responsible doctor.
