Uremic pruritus is a chronic itch in dialysis patients. The exact mechanism of its development is not yet known. Curative therapy is possible only through renal transplantation.
What is uremic pruritus?
Dialysis patients very often experience chronic pruritus, which is also called uremic pruritus. The Latin term is pruritus uraemicus. It is believed that approximately 50 to 90 percent of all dialysis patients are affected by pruritus uraemicus. This is not a disease in its own right, but a symptom. The itching is difficult to control and leads to sleep disturbances and psychological impairment. It has been observed that, in percentage terms, hemodialysis patients suffer from pruritus more frequently than peritoneal dialysis patients. Nevertheless, both procedures can lead to uremic pruritus. Hemodialysis takes place outside the body. In this procedure, blood is drained from the body, cleansed through membranes, and then returned to the body. Peritoneal dialysis takes place inside the body. Here, the peritoneum acts as the filter membrane. In this procedure, a dialysis solution is filled into the abdomen, where it remains for several hours, absorbing urinary substances from the blood via the biological membrane (peritoneum). After a few hours, this used solution is replaced with fresh dialysis solution. Dialysis patients suffer from various skin diseases in addition to uremic pruritus in almost 100 percent of cases. These skin diseases can also lead to excruciating pruritus. However, uremic pruritus must be distinguished from other forms of itching. It has been noted that this particular form of pruritus occurs only in patients requiring dialysis.
Causes
The mechanism of origin of uremic pruritus has not been fully elucidated. There are some attempted explanations, but they have not yet been verified. In renal failure, the skin often dries out. Many patients also suffer from anemia. Serum levels of magnesium and aluminum are often elevated. Parathyroid hormone may also be elevated. All of these factors cause itching. Finally, itching may also be triggered by concomitant diseases of renal insufficiency. These conditions include diabetes mellitus, hypothyroidism, or hepatitis. In some cases, drug intolerances may also be responsible. An increased release of histamine is also discussed as the cause of the itch. It is known, for example, that the concentration of mast cells in the skin is increased in renal insufficiency. Mast cells have a function for the immune system by releasing histamine. Thus, histamine irritates the nerve endings, causing the perception of itching. Furthermore, in chronic renal failure, substance P is also elevated. This stimulates the opioid receptors, which can also be perceived as itching. However, it is observed that this distressing pruritus usually develops during or after dialysis. However, it may also occur between dialyses.
Symptoms, complaints, and signs
Uremic pruritus is not a disease in its own right, but occurs only in the setting of stage 4 and 5 renal insufficiency requiring dialysis. Renal insufficiencies in stages 1 to 3 are still largely asymptomatic. In addition to excruciating, persistent itching, patients also suffer from the other typical symptoms of stage 4 and 5 renal insufficiency, including pain in the kidney area, brown discoloration of the urine, kidney stones or even inflammation of the renal pelvis. Furthermore, nausea, vomiting, reduced mental performance, loss of appetite, water retention, shortness of breath and, above all, skin changes occur. The skin changes appear in the form of scratch marks, open wounds or scars and are the result of scratching during the excruciating itching.
Diagnosis and course of the disease
The itch can be diagnosed as uremic pruritus if it occurs during, after, or even between dialysis treatments. It usually lasts only a few minutes and occurs regularly. The diagnosis of “uremic pruritus” can be made if it occurs as often as three times within two weeks. Physical examination reveals scratch marks.
Complications
Uremic pruritus is primarily associated with severe discomfort for those affected.The possible complications are similar to those of stage four and five renal failure. This can lead to the development of kidney stones or even inflammation of the renal pelvis. In addition, severe gastrointestinal complaints, water retention and shortness of breath occur. In the advanced stages, sufferers also suffer from noticeable skin changes due to constant scratching as a result of the agonizing itching. Open wounds, scratch marks and later also scars are typical. Depending on the course of the underlying disease, uremic pruritus may cause further complications or proceed without symptoms for the affected person. As a rule, no major problems occur during treatment. However, the urea-containing creams may cause skin irritation and occasionally increase itching. Radiation treatment carries the risk of bone disease and changes in tissue structures, which in rare cases can develop into cancer. Painkillers and anti-inflammatory drugs cause side effects and interactions in some patients, for example stomach pain or sensory disturbances. Allergy sufferers are at risk of anaphylactic shock.
When should you see a doctor?
In any case, medical treatment must be given for this disease. It is a very unpleasant complication of dialysis, which in many cases can be limited. The affected person should therefore see a doctor at the first signs and symptoms of the disease, so that there is no further worsening of the symptoms or other complications. Early diagnosis has a positive effect on the further course of the disease. A doctor should be contacted if the patient suffers from very severe itching during dialysis. Likewise, shortness of breath or severe loss of appetite may also be indicative of this disease. It is not uncommon for those affected to also suffer from vomiting or severe nausea. If these symptoms occur over a long period of time and do not disappear on their own, a doctor must be contacted. In this case, the physician responsible for dialysis should be contacted. However, a complete cure can only be achieved by transplanting a kidney.
Treatment and therapy
Curative treatment of uremic pruritus is possible only by renal transplantation. In cases of renal failure requiring dialysis, there are no other curative options. However, some symptomatic treatment options exist that promise relief of pruritus. Thus, topical, physical, surgical and systemic treatments are available. Topical therapy involves the use of creams containing urea to keep the skin moisturized. Furthermore, mild soaps must be applied. Physical therapy, in turn, represents phototherapy with UV-B radiation. Here, irradiation alleviates the agonizing itching. However, the mechanism of action of irradiation has not yet been elucidated. If uremic pruritus is caused by parathyroid hyperfunction, surgical removal of the parathyroid corpuscles promises improvement. Finally, systemic treatments with various drugs can be performed. However, the chances of success vary. In many cases, treatment results are also unsatisfactory. Gamma-linolenic acid has some efficacy because it inhibits the formation of lymphocytes and the synthesis of lymphokines. This prevents inflammatory reactions.
Prevention
Because uremic pruritus is the result of acute or chronic renal failure, its prevention requires attention to the prevention of renal disease. Kidney damage can be caused by hypertension or diabetes, among other things. Therefore, prophylaxis of renal failure and uremic pruritus includes strict weight control, reduction of obesity, plenty of exercise, restriction of salt consumption, balanced diet, and abstention from smoking and alcohol. The diet should be low in calories and fat. At the same time, eating plenty of fruits and vegetables is recommended.
Aftercare
In uremic pruritus, the focus of follow-up examinations and aftercare treatments is generally the symptomatic treatment of the itch. In this regard, follow-up may be limited to relieving or suppressing the itch.Medically, uremic pruritus itself cannot be cured. A corresponding therapeutic treatment concept is lacking. According to the rules, uremic pruritus is only a symptom of renal dysfunction (e.g. renal insufficiency). The pruritus disappears only abruptly with the healing of the underlying disease. Only a kidney transplant can help here. Until then, uremic pruritus can only be treated effectively with a combination of several drugs. The task of follow-up care is to continue the medication started clinically in the affected person and to adapt it to the symptoms of the disease. For this purpose, the patient must be seen regularly as an outpatient. In addition, the patient must learn to adapt his or her living conditions to the disease during aftercare. Itching can also be alleviated by numerous self-help measures. First of all, the trigger factors (triggers of the itching) must be eliminated in the daily life of the affected person. Light clothing (preferably made of cotton) should be worn. When bathing or showering, the water temperature should not exceed 35 degrees Celsius. To prevent the skin from drying out, it is advisable to set up humidifiers in rooms. In addition, personal hygiene should not be overdone (that is, not too hot, not too often and not too long).
This is what you can do yourself
Uremic pruritus requires medical treatment. The condition is treated surgically or conservatively, which should already result in a significant improvement of the individual symptoms. Medical treatment can be supported by various self-help measures. First of all, strict compliance with the doctor’s instructions is important. Above all, the intake of medication, as is necessary for systemic treatment, must be carried out exactly as prescribed. Otherwise, serious complications may occur. Exercise is also recommended. Gentle physical activity supports recovery just as effectively as rest and sparing. The exercise plan is best worked out with a physical therapist. The diet, which must be particularly gentle in advanced kidney disease, also requires detailed analysis by an expert. Patients must drink plenty of fluids and eat a low-fat and low-sugar diet to avoid putting additional strain on the kidneys. The patient should keep a diary of complaints and note any unusual symptoms. In addition, any side effects of the prescribed antihistamines must be written down and reported to the physician. The self-help measures mentioned should be discussed with the physician. The physician can name other measures to help the recovery process.
