Polycystic Kidney Disease (PKD) is simply the presence of a cyst in the kidney or the formation of kidney cysts. It could occur as either Autosomal Dominant Polycystic Kidney Disease (ADPKD) or Autosomal Recessive Polycystic Kidney Disease (ARPKD). Around 1 in 500 to 1,000 people are affected by ADPKD, while ARPKD affects around 1 in 20,000 to 40,000 people.
ADPKD requires that only one parent have the disease to be passed unto the children. Where a parent has ADPKD, each child has a 50% chance of getting the disease. However, both parents must have recessive genes to pass ARPKD on this disease. Each child has a 25% chance of getting the disease, where both parents carry a gene for this disorder.
What is Polycystic Kidney Disease (PKD)?
Polycystic kidney disease (PKD) is a type of kidney disorder that causes multiple benign cysts to develop in the inner lining of a person’s kidneys which causes the kidneys to be enlarged and lose function over time. PKD is usually inherited, except for a few cases where they may arise from gene mutation of the patient.
Types of Polycystic Kidney Disease
There are two types of polycystic kidney disease. They include:
Here, the patient inherits the dysfunctional gene from either or both parents suffering from PKD. ADPKD does not often show up until people are in their mid-adult ages (usually around 30-40 years). There are however cases when symptoms begin to show up during childhood, but such cases are rare.
- Autosomal Dominant Polycystic Kidney Disease (ADPKD)
In this condition, the patient inherits the disease from one or both parents who is a carrier and has a recessive PKD gene but shows no symptoms. Symptoms of ARPKD begin to show from the birth or childhood of a person. The cysts are often present before birth and can detect with the aid of sound on the fetus.
Risk Factors and Possible Complications
Though kidney cysts formed from Polycystic Kidney Disease are non-cancerous, they often cause a decrease or loss of function of the kidney. They can also lead to the development of cysts in the liver and other parts of the body. PKD can also lead to cases of hypertension and kidney failure.
If not detected on time and managed, PKD can lead to further complications like polycystic liver diseases, high blood pressure, and kidney failures.
PKD often causes increased high blood pressure, which if left untreated, can lead to further damage to the kidneys and/or result in heart disease and strokes.
A polycystic kidney can cause uremia, a condition where deterioration in the kidney’s function interferes with its ability to keep wastes, thus resulting in the accumulation of toxins. Uremia could further lead to end-stage kidney (renal) disease where kidney dialysis or a transplant would be required to prolong the life of the patient.
The side or back pains felt due to PKD are sometimes also associated with other complications like urinary tract infection, a kidney stone, or a malignancy.
PKD can lead to a polycystic liver where multiple cysts develop in the liver like that of the kidney. Though statistical evidence has shown that this presents an equal likelihood in males and females, the cysts often grow larger in females due to female hormones and multiple pregnancies.
- Autosomal Recessive Polycystic Kidney Disease (ARPKD)
PKD patients are at higher risk of having a higher risk of aneurysms, a condition that causes bulging and rupturing of blood veins in the brain. This condition appears to occur more in people with an aneurysm in their lineage.
Polycystic kidney disease can sometimes lead to a life-threatening disorder called preeclampsia in pregnant women. However, many women with PKD’s would go through pregnancies successfully. Preeclampsia appears to mostly threaten women who have declined kidney functions or high blood pressure before pregnancy.
- Development of an aneurysm in the brain
Polycystic kidney disease can lead to mitral valve prolapse, a condition where the heart valve stops closing properly, which allows blood to leak backward. This occurs in 1 in 4 adults with PKD.
PKD can cause the wall of the colon to weaken and while pouches or sacs may also erupt.
Diagnosis of PKD
Many people live with polycystic kidney disease for many years without knowing it. However, signs and symptoms of polycystic kidney disease can signal when to see a doctor. People who have a first-degree relative — parent, sibling, or child — with polycystic kidney disease, could be dormant or recessive carriers and thus need to see their doctor for screening for the disorder.
An examination of patients with ADPKD may reveal:
- Heart valve abnormalities
Tests conducted on the patient could include:
- Palpable, bilateral flank masses
- Nodular hepatomegaly
Radiologic imagery conducted may include:
- Urine culture
- Uric acid determination
- Serum chemistry profile
- CBC count
- Intact PTH assay
Treatment of PKD
There is no known cure for a polycystic kidney, however, patients can manage the disease and live better lives, especially when detected on time.
The following modified lifestyles can help the patient manage PKD
- Ultrasonography; used for screening family members of the patient. The imagery reveals possible masses such as liver cysts, pancreatic cysts.
- CT scanning; used for checking kidney stones, suspected tumors
- MRI; used for monitoring kidney size after treatment, as an indication of disease progression.
- MRA; best for sighting intracranial aneurysms
Administering medication and treatment for:
- Taking medications as prescribed by the doctor.
- Reducing intake of high-salt diets; increasing the intake of whole grains.
- Eating plenty of fruits, vegetables
- Maintaining a healthy weight as recommended by the doctor.
- Limiting the intake of alcohol.
- Quitting smoking.
- Exercising at least 30 minutes daily. Moderate exercises like strolling are recommended.
Surgical interventions are required when polycystic kidney disease. The following can be done to help the patient.
- Reducing abdominal pain
- Controlling blood pressure
- Treating cyst infections
- Treating UTIs
- Controlling renal failure related abnormalities
- Treating hematuria
- Preventing cardiac valve infection, if any
- Reducing kidney function decline, if rapid
End-stage kidney diseases advanced from PKD may require:
- Surgical drainage: This is done when the cysts in the kidneys are not responding to antibiotics. It often goes in line with an ultrasonographically guided puncture.
- Fiberoptic-guided or open surgery: This is used to drain the outer walls of cysts to wipe off its symptoms.
- Nephrectomy: This involves the removal of all parts of the kidney in patients with severe kidney issues and is usually the last option for pain control in patients whose cysts are inaccessible.
- Partial hepatectomy: Where the liver has been affected, this involves the removal of a portion of the liver to enable it optimally perform its functions.
- Liver transplantation: When portal hypertension erupts due to polycystic liver or hepatomegaly the patient would require a liver transplant
Symptoms of PKD
Common symptoms of polycystic kidney disease include:
- Increase in size of the abdomen due to enlarged kidneys
- Blood in urine
- Back or side pain
- High blood pressure
- Fullness in the abdomen
- Urinary tract or kidney infections
- Kidney stones
- Kidney failure
Causes of Polycystic Kidney Disease
Polycystic kidney disease is caused by inherited mutated PKD1 and PKD2 genes. These genes are responsible for encoding the proteins polycystin-1 and polycystin-2, respectively, whose jobs are to regulate cells in the kidneys and liver, contribute to the formation of tubular structures, and influence growth and fluid secretion function. However, when any of these genes are mutated, it results in the formation of fluid-filled sacs within the kidney, and subsequently affect other organs such as the liver.
Who can get PKD?
Polycystic kidney disease is a genetic disease passed down through family traits. It can affect anyone of any gender, race, ethnicity, and nationality, as far as the gene is present in the genetic strand of the individual.
What is the difference between ADPKD and ARPKD?
Autosomal Dominant Polycystic Kidney Disease (ADPKD) and Autosomal Recessive Polycystic Kidney Disease (ARPKD) are types of PKD, but their difference is the way they are genetically transmitted.
ADPKD is inherited by the patient from one or both parents who are a dominant carrier, whereas ARPKD is inherited from one or both parents who are a recessive carrier.
When do the symptoms of ADPKD begin?
ADPKD is often called the “adult PKD” because symptoms are not noticed until you become an adult. Only in rare cases do signs begin to show from childhood. Because of the cysts, the kidneys enlarge almost like that of a football and weigh about 30 pounds.
When do the symptoms of ARPKD begin?
Unlike ADPKD, symptoms of ARPKD start from birth and can even be detected in a fetus. This type is chronic and leads to a child managing its symptoms for life and an estimated 33% of the time, a child may need dialysis of a kidney transplant at the age of 10. The kidneys are enlarged from birth causing underdeveloped lines and chronic liver damage. The child gets to live with high blood pressure and has a poor growth system.
Are the kidney cysts in PKD cancerous?
No, they are not cancerous. The cyst that forms in the kidney as a result of PKD is benign, which leads to the decrease and loss of function of the kidneys.