Definition

Polycystic kidney disease is a hereditary condition characterized by the formation of multiple fluid-filled cysts in the kidneys, leading to their enlargement. This can impair kidney function and eventually result in kidney failure. Polycystic kidney disease is the fourth leading cause of kidney failure and can also affect other organs, such as the liver, pancreas, and spleen, leading to various complications.

In adults, polycystic kidney disease is the most common genetic cause of kidney failure, with a significant percentage of patients requiring dialysis or kidney replacement therapy by the age of 60. While cysts may be detected in children or during pregnancy, clinical symptoms typically manifest between the ages of 30 and 40.

The incidence rate of polycystic kidney disease varies, with approximately 4-7 million people affected worldwide. This condition accounts for a significant proportion of patients undergoing kidney replacement therapy. Interestingly, the prevalence of end-stage kidney disease due to polycystic kidneys is lower in the African American population compared to the white population. Symptoms tend to worsen with age, and while kidney failure in children due to polycystic kidneys is rare, the disease may have a slightly more severe course in males compared to females.

Causes

Polycystic kidney disease (PKD) is predominantly hereditary, although rare cases may result from other severe kidney disorders. There are three main types of PKD:

• Autosomal Dominant PKD (ADPKD), also known as adult PKD, is the most common form, accounting for approximately 90% of cases. It is inherited in an autosomal dominant manner, meaning that if one parent has the disease, there is a 50% chance of passing it on to their child. Symptoms typically develop in adulthood, usually between the ages of 30 and 40, although onset may occur earlier or later.
• Autosomal Recessive PKD (ARPKD) is much rarer and occurs when both parents carry the disease gene. If both parents are carriers, their child has a 25% chance of inheriting the disease. Individuals with only one gene from one parent typically do not experience symptoms.
• Acquired Polycystic Kidney Disease (APKD) is not hereditary and typically develops in adulthood. It may occur as a complication of other kidney conditions, particularly in individuals who have experienced kidney failure or are undergoing dialysis therapy. APKD is less common than the inherited forms of PKD and tends to develop later in life.

Risk factor

The primary risk factor for symptomatic polycystic kidney disease (PKD) is genetics, particularly having a family history of the condition. If a parent has PKD, there is a 50% chance of passing the disease on to their child. Additionally, individuals of white ethnicity have a higher risk of developing symptomatic PKD compared to other ethnic groups, although the precise reasons for this disparity are not fully understood.

Symptoms

Many individuals with polycystic kidney disease may not exhibit symptoms related to kidney function for years. Cysts typically grow to around 0.5 inches or larger before patients begin to notice any symptoms. 

Some early symptoms that patients with polycystic kidney disease may experience include:

• Abdominal pain or tenderness
• High blood pressure
• Blood in the urine
• Increased frequency of urination
• Pain in the back or sides
• Urinary tract infections
• Kidney stones
• Back pain or heaviness
• Easily bruised skin
• Pale skin color
• Fatigue
• Joint pain
• Abnormalities in the nails

In the pediatric population with polycystic kidney disease, several symptoms that may be found include high blood pressure, urinary tract infections, and increased frequency of urination. Recognizing these symptoms in children is crucial because they can resemble symptoms of other diseases. It is important to seek medical attention if a child experiences several such symptoms.

Diagnosis

To diagnose polycystic kidney disease, a doctor will typically begin with a medical interview and examination to assess the patient's symptoms. If there is suspicion of polycystic kidney disease, diagnostic tests can be performed. In cases of polycystic kidney disease, the doctor may find tenderness upon palpation in the area of the lower back or abdomen.

Diagnostic tests, such as a complete blood count to assess for anemia or signs of infection and a comprehensive urinalysis to determine the presence of blood, bacteria, or protein in the urine, are commonly conducted.

Imaging studies, including ultrasound (USG) to assess for kidney cysts, CT scan to evaluate even the smallest cysts in the kidneys, MRI scan to assess kidney structure and cysts, and intravenous pyelogram to visualize the blood vessels around the kidneys, can be performed to aid in the diagnosis of polycystic kidney disease.

Management

The goal of therapy for polycystic kidney disease is to control symptoms and prevent potential complications. Controlling high blood pressure is a crucial part of management. Treatments may include medications for high blood pressure, adopting a low-sodium diet, using diuretics to remove excess fluid from the body, and in some cases, surgery to remove cysts and alleviate symptoms.

Complications

Complications that may arise from polycystic kidney disease include:

• End-stage kidney disease
• Hypertension
• Polycystic liver disease (inherited liver cysts within the family)
• Brain aneurysms (problems with the blood vessel walls in the brain)
• Kidney stones
• Infections

Prevention

There isn't a specific prevention method to avoid polycystic kidney disease, but preventing kidney failure is crucial. Early diagnosis enables timely treatment, which can help prevent severe complications. Here are some steps to prevent kidney failure:

• Lifestyle changes:
  • Engage in regular exercise for at least 30 minutes to reduce stress, control weight, and maintain stable blood pressure
  • Aim for weight loss if necessary
  • Ensure adequate sleep of 7-8 hours per night
  • Manage stress effectively
  • Quit smoking to protect kidney health
• Dietary modifications:  Adjust your diet to control blood pressure and protect kidney function. Consider consulting a nutritionist, especially if you have kidney disease like polycystic kidney disease.
• Blood pressure medication: If lifestyle changes aren't sufficient to control blood pressure, your doctor may prescribe medications to help stabilize it.

When to see a doctor?

If your symptoms worsen, such as increased abdominal pain when breathing, it's advisable to seek further consultation with a doctor. The doctor will conduct a medical interview physical examination, and may perform additional diagnostic tests to establish a precise diagnosis and plan appropriate treatment according to your needs.

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