Cystic Kidney Diseases - Types, Causes, Symptoms, Diagnosis, and Treatment

What Is Cystic Disease of the Kidneys?

Cystic kidney disease is not a single condition but a group of disorders that result in the formation of cysts on the kidney surface. The kidneys are vital and principal organs of the urogenital system. They filter the blood, form urine, and maintain fluid and electrolyte levels in the body. If the cysts develop on the surface of the kidneys, they become enlarged and fail to function over time. Cysts are round and fluid-filled cavities or sacs that may or may not be lined by an epithelium. They are of various sizes and form anywhere in the body. Normally, the cysts are benign (non-cancerous) but cause severe complications if they turn malignant (cancerous). The most common cystic kidney disease is autosomal dominant polycystic kidney disease and affects adults mainly. Sometimes, kidney cysts are present since birth, but the condition goes unnoticed because the patient is asymptomatic.

What Are the Major Types of Cystic Kidney Disease?

Cystic kidney disease might be a result of defective genes (mutations) passed on from the parents to their children or acquired during their lifetime. The genetic cystic kidney diseases have been described in the table below:

The acquired cystic kidney diseases have been described in the table below:

What Are the Causes of Cystic Kidney Diseases?

There are several causes of cystic kidney disease. They might be caused due to systemic conditions, mutations, and developmental disorders. The individual causes of each cystic kidney disease have been described below:

1. Developmental Problems - Multicystic dysplastic kidney is an example of a condition where cysts form on the kidney surface if they fail to develop correctly. The cysts might also develop when the flow of urine from the kidneys is obstructed. As the child grows, the surface of the kidneys is covered by cysts resembling a ‘bunch of grapes.’

2. Hereditary Causes - There are multiple cystic kidney diseases that are caused due to the transfer of defective genes from the parents to their children. The diseases have been described below:

   • Polycystic Kidney Disease - There are two types of polycystic kidney disease based on the pattern of inheritance: autosomal dominant and autosomal recessive. In autosomal dominant polycystic kidney disease (ADPKD), if one parent has the defective gene, there is a 50 percent chance that the child will get the disorder. In autosomal recessive polycystic kidney disease (ARPKD), if both parents have defective genes, it is a 25 percent chance that the child will get the disorder.

   • Glomerulocystic Kidney Disease (GCKD) - It is a rare disease transmitted from parents to their children. The exact genes that cause the disease have not been identified.

   • Nephronophthisis - It is a genetic condition mainly caused by a defect in the nephronophthisis genes (NPHP1 to NPHP5).

   • Medullary Cystic Kidney Disease - It is caused by a defect in the medullary cystic kidney disease type 1 and 2 (MCKD1 and MCKD2) genes.

3. Acquired Cystic Kidney Disease - The exact cause of this disease is unknown. However, two theories support the occurrence of cystic kidney disease. One theory states that cysts form due to the obstruction of kidney tubules. According to the second theory, the accumulation of chemicals and growth factors gives rise to cysts.

What Are Some of the Symptoms of Cystic Kidney Disease?

There are different types of cystic kidney diseases, but they present with common symptoms. The symptoms of cystic kidney disease are listed below:

1. Pain and burning sensation while urinating.

2. The patient experiences pain in the lower back and abdominal region.

3. Hematuria (blood in the urine) is one of the most common findings.

4. The cysts might rupture and bleed.

5. Hypertension or high blood pressure is usually seen due to kidney failure.

6. The kidneys become enlarged due to the presence of cysts.

7. The risk of kidney infections and stones increases.

8. The patient experiences frequent headaches.

What Methods Are Used to Diagnose Cystic Kidney Disease?

The diagnosis of cystic kidney disease is based on medical history, physical examination, laboratory tests, and imaging tests. The methods used to diagnose cystic kidney disease have been mentioned below:

• Medical History - The medical history provides an insight into the general health of the patient, the symptoms of the disease, like abdominal pain, bleeding due to cyst rupture, and family history. Family history helps to rule out genetic cystic diseases.

• Physical Examination - The doctor checks for the physical signs of cystic kidney disease and measures blood pressure. It is because blood pressure is usually high in cystic kidney disease.

• Laboratory Tests - The below-mentioned laboratory tests are usually recommended to diagnose cystic kidney disease:

  • Blood Tests - The doctor might order the patient to undergo a blood test to check the levels of minerals and electrolytes in the blood. If the kidneys are inefficient in working due to the presence of cysts, the levels of sodium and potassium are usually high.

  • Urine Tests - The patient needs to collect the urine in a container or a sterile bag. The urine sample is examined in the laboratory under a microscope. It helps to detect the contents of urine. For example, if the white blood cells are present in the urine and show decreased osmolality, autosomal recessive polycystic kidney disease can be suspected.

  • Genetic Testing - The genes of the person are examined because diseases like polycystic kidney disease, glomerulocystic kidney disease, medullary cystic kidney disease, and nephronophthisis are caused due to defective genes.

• Imaging Tests - The following diagnostic tests are done:

  • Ultrasound - It is a diagnostic test that helps to obtain images of the internal organs of the body without exposing the patient to X-rays. The doctor moves the transducer over the abdomen, and the images are obtained on the computer screen. The ultrasound helps to check the size and shape of the kidneys after the cysts have formed.

  • Intravenous Pyelogram - In this procedure, a dye is injected into the body through the veins. X-rays are obtained at different angulations as the dye flows through the urinary tract. In medullary sponge disease, the cysts appear like a “bouquet of flowers” in the intravenous pyelogram test. A non-functioning or deformed kidney is usually seen in medullary cystic kidney disease when the dye gets deposited on the kidney surface.

  • Computerized Tomography (CT) Scans - This procedure provides three-dimensional (3D) images of the internal organs of the urogenital system. The patient is laid on a table that slips into a device where the X-rays are taken. These images help to detect the cysts on the kidney surface that have turned malignant.

  • Magnetic Resonance Imaging (MRI) - As the name suggests, this technique uses a combination of magnetic fields and radio waves to produce the images. It helps to check the condition of the kidneys and if the cysts have turned malignant.

How Is Cystic Kidney Disease Managed?

If the kidney cysts are small in size and the patient does not present with any symptoms, no treatment is required to be done. However, the following treatment options are recommended for treating kidney cysts:

1. Drug Therapy - A drug known as Tolvaptan is recommended for patients suffering from autosomal dominant polycystic kidney disease. It helps to reduce the growth of cysts, but the drug should be taken only after consultation with the doctor. It is because it causes serious injury to the liver.

2. Management of Hypertension - Hypertension or high blood pressure in cystic kidney disease can be managed by medications like Captopril, Enalapril, Fosinopril, Losartan, and Candesartan. Blood pressure can also be managed by reducing the consumption of salty and spicy food items. A low-fat and high-protein diet helps to keep the blood pressure normal.

3. Management of Pain - The patient usually experiences pain in the lower back region due to cysts. However, the routine drug Acetaminophen is of no use in pain that arises due to cysts. To manage pain, the doctor injects a fluid known as a sclerosing agent. It helps to reduce the cyst size and manage pain.

4. Surgical Procedures - Surgical intervention is required when the kidneys fail to work. Aspiration or resection can be done to remove the cysts from the kidneys. The procedures have been described below:

   • Aspiration - The cyst is located with the help of ultrasound, and a needle is inserted. The fluid is withdrawn from the cyst and discarded or sent for laboratory examination. As the fluid has been withdrawn, the cyst ruptures and reduces in size.

   • Resection - It is a procedure in which the cyst is removed surgically. The doctor makes small incisions near the abdomen. A telescope-like instrument known as the laparoscope is inserted to visualize the cyst and remove it.

5. Management of Hematuria - Hematuria or blood in the urine is a sign of urinary tract infection. It might also occur due to the rupture of cysts. The patient needs to drink plenty of water to increase urine concentration and prevent the formation of clots in the urinary tract.

6. Kidney Transplant - A healthy kidney (donor's kidney) is transferred to the body to replace the infected one. The donor could be a friend or a family member.

What Are the Complications of Cystic Kidney Disease?

The following complications occur if the kidney cysts are left untreated for long:

1. The kidneys increase in size due to the presence of cysts. As a result, they fail to function, and the fluid and electrolyte levels of the body are disturbed.

2. The risk of liver and pancreatic cysts increases in polycystic kidney disease. If the liver and pancreas are affected by cysts, it becomes difficult for the body to carry out important functions.

3. Hypertension or high blood pressure is the most common complication of polycystic kidney disease; If the blood flows under pressure, the risk of heart and kidney disease increases.

4. Infants and young children fail to grow and develop properly if the kidneys are damaged due to cysts.

Conclusion:

Cystic kidney disease is a condition in which multiple fluid-filled sacs, known as cysts, form on the kidney surface. There are several causes of cyst formation. They might arise due to defective genes passed on from the parents to their children or a child being born with cysts. The symptoms are usually common, like abdominal pain, headache, and difficulty in passing urine. Small cysts heal on their own and do not require any treatment. However, surgical intervention is required when the cysts interfere with the functioning of the kidneys. Timely diagnosis and treatment are the two keys to saving the kidneys from getting damaged. Dialysis and kidney transplant procedures are a boon for patients suffering from kidney failure.