OVERVIEW

What is Polycystic Kidney Disease?

Polycystic kidney disease (PKD) is a congenital kidney abnormality and a genetic disorder characterized by progressive dilation of multiple tubular segments or glomerular sacs in both kidneys, forming numerous fluid-filled cystic lesions (i.e., cysts).

A normal kidney is a solid organ (similar to a pig's kidney) with a smooth surface, whereas a polycystic kidney may resemble a cluster of grapes. In severe cases, the entire kidney is covered with cysts, leading to an enlarged kidney size but a reduction in functional kidney tissue.

Is Polycystic Kidney Disease a Malignant Tumor?

No, polycystic kidney disease is not a malignant tumor; it is a congenital malformation of the urinary system.

Is Polycystic Kidney Disease Hereditary?

Yes, polycystic kidney disease is a genetic kidney disorder. Based on inheritance patterns, it is divided into two main types^[1]:

• Autosomal Dominant Polycystic Kidney Disease (ADPKD): If one parent has this type of PKD, each child has a 50% chance of inheriting the disease.
• Autosomal Recessive Polycystic Kidney Disease (ARPKD): Both parents carry the mutated gene without showing symptoms, and their offspring have a 25% chance of developing the disease.

Which Kidney is More Commonly Affected by Polycystic Kidney Disease?

Polycystic kidney disease typically occurs bilaterally (in both kidneys)^[2].

Is Polycystic Kidney Disease Common?

PKD is relatively common clinically, with autosomal dominant polycystic kidney disease (ADPKD) being the predominant form. Since ADPKD often manifests in adulthood, it is also called adult-onset polycystic kidney disease, with an incidence rate of approximately 1/1,000 to 1/400.

Autosomal recessive polycystic kidney disease (ARPKD), also known as infantile polycystic kidney disease, usually presents in the neonatal or infant period. It is rarer, with an incidence of about 1/40,000 to 1/20,000. About 25%–30% of affected newborns die in the neonatal period, and among those who survive, the 15-year survival rate is 50%–80%^[1].

SYMPTOMS

What are the manifestations of polycystic kidney disease?

Early-stage polycystic kidney disease usually has no symptoms, but as cysts grow larger and more numerous in the kidneys, progressive kidney failure may occur.

If left uncontrolled, polycystic kidney disease can cause the kidneys to enlarge to more than five times their normal size within a few years, leading to loss of kidney function^[2].

Other possible kidney-related manifestations include: hypertension, urinary tract infections, impaired urine concentration, hematuria, kidney stones, and acute or chronic lower back or abdominal pain; protein excretion is usually not a prominent feature^[2,3].

All complications are directly related to the extent of kidney cyst involvement, which can be assessed by measuring total kidney volume.

• Hypertension: Elevated blood pressure (above 140/90 mmHg) may occur early, accompanied by symptoms such as dizziness and fatigue.
• Hematuria: Patients may experience visible hematuria at some point in the disease course, often before kidney function loss, and it may be the primary complaint. Triggers such as urinary tract infections or strenuous activity are often identified, and episodes may recur. In polycystic kidney disease, gross hematuria suggests faster disease progression.
• Impaired urine concentration: Most patients have mild impairment in urine concentration, commonly reporting increased thirst, polyuria, nocturia, and frequent urination. Reduced urine-concentrating ability is one of the earliest signs of polycystic kidney disease, initially mild but worsening with age and declining kidney function.
• Kidney stones: Kidney stones occur in up to 25% of patients. Unlike idiopathic stone formers (where calcium oxalate predominates), more than half of stones in polycystic kidney disease are composed of uric acid, with the remainder mostly calcium oxalate.
• Back and abdominal pain: These are common issues in polycystic kidney disease and may stem from intrarenal or extrarenal causes. Acute kidney-related pain may result from infection (cyst or parenchyma), kidney stones, or cyst hemorrhage. Pain may also arise from liver cysts. Chronic kidney pain is more common in advanced disease with enlarged kidneys, often described as dull and persistent, likely due to capsular stretching or renal pedicle traction. Pain is typically localized to the lower back or flank, may be continuous or intermittent, and ranges from mild (dull, distending) to severe (knife-like, stabbing). Sudden severe pain or worsening pain may indicate cyst rupture, urinary obstruction, or infection.

At what age do symptoms of adult-onset polycystic kidney disease typically appear?

Symptoms usually develop after 30–40 years of age, though some individuals remain asymptomatic throughout life^[2].

What other conditions may complicate polycystic kidney disease?

Polycystic kidney disease is a common genetic disorder that may also involve polycystic liver disease, mitral valve prolapse, intracranial aneurysms, pancreatic cysts, and colonic diverticula.

CAUSES

What are the causes of polycystic kidney disease?

The disease is closely related to heredity and may be caused by genetic inheritance or spontaneous gene mutations. Mutations in either the PKD1 or PKD2 gene are responsible for most cases of polycystic kidney disease^[1].

DIAGNOSIS

What tests are needed to confirm the diagnosis of polycystic kidney disease?

The diagnosis of polycystic kidney disease is generally not difficult. Common auxiliary examinations include urinary tract color Doppler ultrasound, abdominal plain film (X-ray), intravenous urography (IVU), urinary tract CT, urinalysis, and renal function tests.

What are the functions, advantages, and disadvantages of polycystic kidney disease tests?

• Abdominal plain film (X-ray): When kidney volume increases significantly, enlarged kidney shadows with irregular shapes can be observed. However, this test has limited diagnostic value and is rarely used clinically today.
• Intravenous urography (IVU): This test involves injecting a contrast agent intravenously, which is excreted by the kidneys, revealing the morphology of the renal pelvis and calyces. It has certain diagnostic features for polycystic kidney disease, showing multiple renal cysts and their compression on the renal pelvis. However, due to the irritative effects of contrast agents on tissues, better alternatives are now available.
• Urinary tract color Doppler ultrasound: This test is highly characteristic for diagnosing the disease, being simple, convenient, non-invasive, and cost-effective. It is often used for initial screening, presenting as multiple fluid-filled hypoechoic areas.
• Urinary tract CT scan: This test is convenient and non-invasive, typically showing smooth, uniform round or oval lesions^[3]. It can also determine cyst size, location, and shape, aiding surgical planning.
• Urinalysis: Detects the presence of hematuria (red blood cells in urine, which are absent in healthy individuals).
• Renal function tests: Assess overall kidney function and guide treatment decisions.

Is polycystic kidney disease the same as multiple renal cysts?

No^[3].

Polycystic kidney disease is hereditary, usually bilateral, and often accompanied by liver cysts and renal insufficiency. In contrast, multiple renal cysts can result from various conditions such as trauma, inflammation, or tumors, are typically unilateral, and usually do not impair renal function or exhibit hereditary patterns.

TREATMENT

How is polycystic kidney disease treated?

Treatment varies depending on the stage of the disease:

• Early stage: Symptomatic and supportive treatment is often used, including blood pressure control, infection prevention, adequate rest, avoiding fatigue, and a high-quality low-protein diet.
• Middle stage: Renal cyst decompression surgery, especially for patients with rapid disease progression, significant discomfort, declining kidney function, or progressively increasing blood pressure. However, polycystic liver disease cannot be treated simultaneously^[2,3].
• Late stage: Dialysis and kidney transplantation. Since the cyst walls can still synthesize erythropoietin, anemia is generally uncommon. Hemodialysis can be maintained for a longer period, but there is a high risk of thrombosis blocking fistulas^[2,3].

Can polycystic kidney disease be completely cured?

No, but treatment can slow disease progression and reduce complications.

Is surgery meaningful for late-stage polycystic kidney disease?

For patients with late-stage polycystic kidney disease, renal cyst decompression surgery is generally not beneficial and may further impair kidney function.

What factors influence the prognosis of polycystic kidney disease?

The prognosis is related to gender, age of onset, kidney size, presence of hypertension, visible hematuria, and whether polycystic liver disease is also present.

What are the common causes of death in untreated late-stage adult polycystic kidney disease?

Common causes include uremia, complications of hypertension, and cerebral hemorrhage.

DIET & LIFESTYLE

What should patients with polycystic kidney disease pay attention to in terms of diet and lifestyle?

Polycystic kidney disease is a chronic progressive condition. Paying attention to diet and lifestyle habits can help slow disease progression.

In daily life, adequate rest and avoiding overexertion are recommended. If there are no symptoms such as back pain caused by polycystic kidney disease, normal activities can be maintained without strict restrictions. However, if the kidneys are significantly enlarged or individual cysts are large, it is important to protect the abdomen and lower back to prevent trauma that could lead to cyst rupture.

In terms of diet, poor dietary habits may worsen kidney damage. Therefore, the following recommendations are advised:

• High-quality, low-protein diet: Protein is essential but should be consumed in moderation to reduce kidney burden. Animal-based proteins (e.g., eggs, lean meat, fish) are preferred, while soy products (e.g., tofu) and nuts (e.g., peanuts) should be limited^[2].
• Low-salt diet: Especially for those with high blood pressure, salt intake should be strictly controlled.
• Low-phosphorus, high-calcium diet: Increase consumption of fresh fruits and vegetables.
• Low-purine diet: Reduce intake of organ meats.
• Quit smoking and alcohol: Alcohol raises blood pressure, worsening the condition, while nicotine in tobacco constricts blood vessels, impairing kidney blood supply and causing further damage.

Does polycystic kidney disease require regular follow-up examinations?

Yes.

Since polycystic kidney disease is a chronic progressive condition, regular follow-ups are necessary. Key examinations include urinary tract ultrasound, CT scans, urinalysis, kidney function tests, blood tests, electrolyte checks, abdominal ultrasound, and echocardiography to monitor kidney and other organ conditions^[3].

Does polycystic kidney disease affect fertility?

Polycystic kidney disease does not involve complications in reproductive organs and generally does not affect fertility.

PREVENTION

Can Polycystic Kidney Disease Be Prevented?

Since it is related to genetics, there is currently no effective prevention method. If there is a family history of polycystic kidney disease, it is recommended that children undergo regular kidney check-ups for early detection and treatment.