Cystic kidneys is a collective term for certain hereditary kidney diseases. In these, numerous fluid-filled cavities (cysts) develop in both kidneys. These grow over time, enlarging the kidneys and at the same time displacing the normal kidney tissue. This leads to a considerable reduction in kidney function and even chronic kidney failure.
Find out more about the symptoms, diagnosis and treatment of this kidney disease here and find selected specialists for cystic kidneys.
Doctors refer to cystic kidneys as polycystic kidney disease (PKD). They distinguish between two main forms:
As the cysts gradually enlarge, ADPKD does not cause any symptoms for a long time. The first symptoms appear in adulthood between the ages of 20 and 40. In many cases, high blood pressure (hypertension) leads the way. Those affected often first notice pain in the flanks, groin, back or also in the abdominal and stomach area.
In many cases, the cysts bleed and the urine turns reddish (haematuria). The cysts are also an ideal breeding ground for bacteria, which is why repeated urinary tract infections occur, particularly in women.
If the cysts disrupt the urine flow, components of the urine crystallize and kidney stones form. Many sufferers also experience symptoms such as tiredness and fatigue.
Cramps in the legs and an enlarged abdomen are also observed. As the disease progresses, it also leads to breathing problems, which can be life-threatening.
The symptoms of ARPKD are similar. However, they occur earlier, in newborns and children.
Healthy kidney and cystic kidney in comparison @ designua /AdobeStock
Cystic kidneys are caused by a change in the genetic material (genes). Around two thirds of those affected have the disease from birth. Very rarely, cystic kidneys develop because the genes mutate spontaneously after fertilization.
In ADPDK, one of the two PKD genes - PKD1 and PKD 2 - is affected by a mutation. The two genes regulate the formation of the membrane proteins polycysteine-1 and polycysteine-2.
These proteins play an important role in the formation of the kidney structure. If these proteins are defective due to mutations, many cysts develop in both kidneys.
A mutation in the PDK1 gene leads to severe progression and kidney failure in 85 to 90 percent of cases.
In ARPKD, another gene is responsible for the disease, PKHD1 (polycystic kidney and hepatic disease 1). This is involved in the formation of the protein fibrocystin. If there is a mutation in the gene, cysts form even before birth. The disease therefore progresses more quickly.
In the dominant-autosomal inheritance of ADPKD, only one parent carries the disease.
In the autosomal recessive inheritance of ARPKD, the gene on the maternal and paternal chromosome must be mutated.
Therefore, the probability of developing ADPKD is 50 percent (the dominant gene prevails). In ARPKD, it is 25 percent (the recessive genes only prevail in the pair).
In all cases, excessive epithelium forms in the collecting duct (fine tube for urine drainage), resulting in cysts.
The doctor diagnoses cystic kidneys based on the patient's medical history and imaging.
When taking the medical history, he focuses on the family history, as 70 percent of those affected have relatives with a similar disease.
During the physical examination, he palpates the enlarged kidneys and measures the blood pressure.
If the family history is positive, the enlarged kidneys can be palpated and/or the blood pressure is elevated, the doctor will have a urinalysis carried out. The urinalysis is used to check the kidney values. However, these do not have to be abnormal.
Finally, the doctor confirms the diagnosis with the help of an ultrasound scan (upper abdominal sonogram). This shows the enlarged kidneys and any cysts.
If the ultrasound image is not clear, he will also carry out a computer tomography scan. This allows the doctor to determine not only the kidney enlargement, but also the cysts and any bleeding.
In newborns, the detection of a single cyst is sufficient to confirm the diagnosis if there is a family history of known cases.
Cystic kidneys must be treated, otherwise kidney function will deteriorate. The treatment measures are aimed at alleviating the symptoms and slowing down the progression of the disease.
It is important to treat high blood pressure, as this causes additional damage to the kidneys and accelerates the progression of the disease. The doctor prescribes antihypertensive drugs such as ACE inhibitors or angiotensin receptor blockers for this purpose. Existing urinary tract infections are also treated with antibiotics.
If the kidneys are no longer able to fulfill their function (terminal renal insufficiency), dialysis (blood washing) is required. The doctor will also consider a kidney transplant in these cases.
Dialysis for cystic kidneys @ Lumos sp /AdobeStock
As the disease often also affects other organ structures, various specialists are involved in the treatment :
Despite treatment, cystic kidneys show a progressive course that leads to the need for dialysis 8 to 13 years after diagnosis.
Half of ARPKD patients require dialysis from the age of 50. The other half reach the age of 70 without needing dialysis.
The earlier the symptoms appear, the faster the disease progresses.
The average life expectancy of ARPKD patients is 10 years. 50 percent of affected children die as newborns.
Cystic kidneys are a serious kidney disease. As they are hereditary, doctors cannot treat them causally. They are therefore limited to symptomatic therapy. It progresses gradually and eventually leads to kidney failure and the need for dialysis.
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