Cystic Kidneys or Polycystic Kidney Disease - Information and Specialists

Doctors refer to cystic kidneys as polycystic kidney disease (PKD). They distinguish between two main forms:

• Autosomal dominant polycystic kidney disease (ADPKD): This form is the most common type of polycystic kidney disease and affects adults.
• Autosomal-recessive polycystic kidney disease (ARPKD): This form is much rarer, affects children, and is associated with a low life expectancy.

Both forms are autosomal inherited disorders.

Since the cysts grow gradually, 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) is a key indicator. The first symptom people often notice is pain in the flanks, groin, back, or even in the abdominal and stomach areas.

In many cases, the cysts bleed, leading to blood in the urine. Additionally, the cysts provide an ideal breeding ground for bacteria, which is why women in particular experience recurrent urinary tract infections.

If the cysts obstruct urine flow, components of the urine crystallize, leading to the formation of kidney stones. In addition, many patients suffer from symptoms such as fatigue and exhaustion.

Those affected also experience leg cramps and an enlarged abdominal circumference. In later stages, the disease additionally leads to breathing problems that can be life-threatening.

The symptoms of ARPKD are similar. However, they appear earlier, in infancy and childhood.

Comparison of a healthy kidney and a kidney with cysts @ designua /AdobeStock

The cause of polycystic kidney disease lies in a genetic mutation. About two-thirds of those affected have had the condition since birth. Very rarely, polycystic kidney disease develops because the genes spontaneously mutate after fertilization.

In ADPDK, one of the two PKD genes—PKD1 or PKD2—is affected by a mutation. These two genes regulate the production of the membrane proteins polycystin-1 and polycystin-2.

These proteins play an important role in the development of kidney structure. If these proteins are defective due to mutations, numerous cysts develop in both kidneys.

A mutation in the PKD1 gene leads to a severe course of the disease and kidney failure in 85 to 90 percent of cases.

In ARPKD, a different gene is responsible for the disease: PKHD1 (polycystic kidney and hepatic disease 1). This gene is involved in the production of the protein fibrocystin. If there is a mutation in this gene, cysts begin to form even before birth. As a result, the disease progresses more rapidly.

In the autosomal dominant inheritance pattern of ADPKD, only one parent is a carrier of the disease.

In the case of autosomal recessive inheritance of ARPKD, the gene must be mutated on both the maternal and paternal chromosomes.

Therefore, the probability of developing ADPKD is 50 percent (the dominant gene prevails). For ARPKD, it is 25 percent (the recessive genes prevail only when both are present).

In all cases, excessive epithelial tissue forms in the collecting duct (a thin tube that drains urine), leading to the formation of cysts.

The doctor diagnoses polycystic kidney disease based on the medical history and imaging.

During the medical history, the doctor focuses on family history, as 70 percent of those affected have relatives with a similar condition.

 During the physical examination, the doctor palpates the enlarged kidneys and measures blood pressure.

If there is a positive family history, the enlarged kidneys are palpable, and/or blood pressure is elevated, the doctor orders a urinalysis. The urinalysis is used to check kidney function. However, the results do not necessarily have to be abnormal.

The doctor finally confirms the diagnosis using an ultrasound scan (upper abdominal sonogram). During this scan, the doctor can see the enlarged kidneys as well as any cysts present. 

If the ultrasound image is inconclusive, the doctor will also perform a computed tomography (CT) scan. This allows the doctor to detect not only the enlarged kidneys but also any cysts and possible hemorrhages. 

In newborns, the detection of a single cyst is sufficient for confirmation if there is a family history of the condition.

You must seek treatment for polycystic kidney disease, as kidney function will otherwise deteriorate. Treatment measures aim to alleviate symptoms and slow the progression of the disease.

It is important to treat high blood pressure, as it causes additional damage to the kidneys and accelerates the progression of the disease. To this end, the doctor prescribes blood pressure-lowering medications such as ACE inhibitors or angiotensin receptor blockers. The doctor also treats any urinary tract infections with antibiotics.

If the kidneys are no longer able to function (end-stage renal failure), dialysis or a kidney transplant is necessary.

Since the disease often affects other organ systems as well, various specialists are involved in the treatment:

• Cysts often develop in the liver (30 to 50 percent of cases) or pancreas (10 percent). Gastroenterologists or hepatologists are responsible for managing these cases.
• In addition, heart problems such as heart valve disorders (25 to 30 percent of those affected) often occur, which are managed by a cardiac surgeon.
• A kidney specialist (nephrologist) coordinates the interdisciplinary team. This specialist also conducts regular follow-up examinations using ultrasound and kidney function tests.

Dialysis for Polycystic Kidney Disease @ Lumos sp /AdobeStock

Despite treatment, the disease follows a progressive course, leading to the need for dialysis 8 to 13 years after diagnosis. 

ARPKD presents with severe symptoms as early as childhood. Half of those with ARPKD require dialysis by age 50. The other half reach age 70 without needing dialysis (blood filtration).

The general rule is: The earlier the symptoms appear, the faster the disease progresses.

The average life expectancy for ARPKD patients is 10 years. Fifty percent of affected children die during the neonatal period.

Polycystic kidney disease is a serious kidney disorder. Since it is hereditary, doctors cannot treat the underlying cause. They therefore limit treatment to managing symptoms. The disease progresses gradually and ultimately leads to kidney failure and the need for dialysis.