Polycystic Kidney Disease (PKD)

Polycystic kidney disease (PKD) is a kidney disorder in which numerous fluid-filled sacs, called cysts, develop within the kidneys. These cysts are not cancerous, but they can range from the size of a pinhead to the size of a grapefruit and, over time, multiply and enlarge to the point where they interfere with normal kidney structure and function.

PKD is one of the most common inherited kidney conditions, and one of the leading genetic causes of kidney failure worldwide. While the kidneys are affected most severely, PKD is truly a whole-body condition — cysts can also form in the liver and pancreas, and the underlying gene changes are linked to problems affecting the blood vessels in the brain, the heart valves, and the walls of the colon. Because of this, PKD is best understood and managed not simply as a kidney problem, but as a lifelong condition that calls for coordinated, whole-person care.

Types of PKD

PKD is not a single condition but a family of related genetic disorders. The two main forms differ in how they are inherited, when they typically appear, and how severely they affect the body.

Autosomal Dominant PKD (ADPKD): The most common form, accounting for the great majority of PKD cases. A child of a parent with ADPKD has a 50% chance of inheriting the condition. Symptoms usually appear in adulthood, most often between the ages of 30 and 50, although cysts can be present from birth and occasionally cause symptoms in childhood.
Autosomal Recessive PKD (ARPKD): A much rarer and generally more severe form, caused by changes in the PKHD1 gene. Both parents must carry a copy of the altered gene for a child to be affected, giving a 25% chance of the condition in each pregnancy where both parents are carriers.

What Causes Polycystic Kidney Disease

PKD is a genetic condition caused by changes (mutations) in specific genes that are responsible for the normal structure and function of kidney tubule cells. These mutations disrupt the way cells in the kidney tubules grow and divide, causing fluid-filled cysts to form and gradually enlarge, which distorts and compresses healthy kidney tissue.

ADPKD (PKD1 and PKD2 genes): The PKD1 and PKD2 genes are responsible for the great majority of ADPKD cases. PKD1 mutations tend to lead to earlier onset and faster progression to kidney failure than PKD2 mutations.
ARPKD (PKHD1 gene): Almost all cases of ARPKD are caused by mutations in the PKHD1 gene, which affects a protein important for the normal development of kidney and bile duct tissue.
New mutations: A small proportion of people with ADPKD have no family history of the condition. These cases arise from a new (de novo) genetic mutation and can then be passed on to the next generation in the usual dominant pattern.
Not a lifestyle disease: Because PKD is fundamentally a genetic condition, it cannot be caused or triggered by diet, lifestyle or environmental exposures — though, as discussed below, lifestyle factors can meaningfully influence how quickly the disease progresses once it is present.

Symptoms of Polycystic Kidney Disease

Symptoms depend on the type of PKD and, for ADPKD, often develop slowly and may not be noticed until cysts have grown significantly or complications occur.

Symptoms of ADPKD (usually appearing in adulthood)

Pain or a dull ache in the back, sides or abdomen, as enlarging kidneys stretch surrounding tissue
High blood pressure — often one of the earliest signs, sometimes appearing years before kidney function declines
Blood in the urine (haematuria), which may come and go
Frequent urinary tract infections or kidney infections
Kidney stones
A feeling of fullness or an enlarged abdomen due to enlarged kidneys or liver
Headaches, which may occasionally signal high blood pressure or, rarely, a brain aneurysm
Reduced kidney function, detected on blood tests, as the condition progresses

Symptoms of ARPKD (usually appearing before or shortly after birth)

Enlarged, firm kidneys detected on prenatal ultrasound
Low levels of amniotic fluid during pregnancy, which can affect lung development
Breathing difficulties in the newborn period due to underdeveloped lungs
A swollen abdomen and low birth weight
High blood pressure, sometimes appearing in infancy or early childhood
Signs of liver involvement, such as an enlarged liver or, in later childhood, evidence of liver scarring (fibrosis)

Risk Factors for PKD

PKD is a genetic condition, so the primary risk factor is family history. However, several additional factors influence how severe the disease becomes and how quickly it progresses:

Family history: Having a parent with ADPKD gives a 50% chance of inheriting the condition; having two parents who both carry an ARPKD gene change gives a 25% chance per pregnancy.
Specific gene involved: PKD1 mutations are generally associated with larger kidneys, earlier onset of symptoms and faster progression to kidney failure than PKD2 mutations.
Sex: Men with ADPKD, and women who have not gone through pregnancy, tend to experience somewhat faster loss of kidney function on average, although the difference narrows after menopause.
Uncontrolled high blood pressure: Persistently high blood pressure accelerates cyst growth and kidney function decline, making blood pressure control one of the most important modifiable factors in PKD.
Total kidney volume: Larger kidney and cyst volume at diagnosis, measured by imaging, is one of the strongest predictors of how quickly the disease will progress.
Frequent urinary complications: Recurrent urinary tract infections, kidney stones, and episodes of visible blood in the urine have all been linked with a somewhat faster decline in kidney function over time.

Possible complications of Polycystic Kidney Disease (PKD)

If left unmanaged, PKD can lead to a range of complications affecting the kidneys and other organs:

Chronic kidney disease that progressively worsens and may lead to kidney (end-stage renal) failure requiring dialysis or transplantation
High blood pressure, which can in turn accelerate kidney damage and increase cardiovascular risk
Kidney stones and recurrent urinary tract or kidney infections
Cysts in the liver, which are common in ADPKD and, though usually not affecting liver function, can occasionally cause discomfort or complications
Cysts in the pancreas and, less commonly, other organs
Intracranial (brain) aneurysms — a bulge in a blood vessel in the brain, which occurs more frequently in people with ADPKD, particularly those with a family history of aneurysm, and can be serious if it ruptures
Heart valve abnormalities, such as mitral valve prolapse
Diverticula (small pouches) in the wall of the colon
High blood pressure during pregnancy (pre-eclampsia), which occurs more frequently in women with ADPKD
In ARPKD, complications can be life-threatening in the newborn period due to underdeveloped lungs, and later childhood complications may include liver scarring and portal hypertension

How PKD Is Diagnosed

Diagnosis usually combines a detailed family history with imaging of the kidneys, and increasingly, genetic testing — particularly when family history is unclear or a definitive diagnosis is needed for family planning.

Family & Clinical History: A detailed discussion of symptoms, blood pressure history and family history of kidney disease, aneurysms or early kidney failure, which often points strongly toward the diagnosis before any test is done.
Imaging (Ultrasound, CT or MRI): The primary method of diagnosis. Ultrasound is typically used first as it is quick, safe and radiation-free; CT and MRI provide more detailed images and are used to measure total kidney and cyst volume, which helps guide treatment decisions and monitor progression over time.
Genetic Testing: Identifies mutations in the PKD1, PKD2 or PKHD1 genes. Particularly useful when imaging findings are inconclusive, when a young or asymptomatic relative wishes to know their status, when family planning or living kidney donation is being considered, or to confirm diagnosis in atypical cases.
Blood & Urine Tests: Kidney function tests (such as creatinine and estimated glomerular filtration rate, or eGFR), urinalysis to check for blood or protein, and screening for related conditions help assess how well the kidneys are working and monitor change over time.
Prenatal Ultrasound: ARPKD is often first identified during routine pregnancy ultrasound scans, which may show enlarged kidneys or reduced amniotic fluid.
Disease Classification: For ADPKD, total kidney volume adjusted for height and age (the Mayo Imaging Classification) is commonly used to estimate the likely rate of future disease progression and to help determine who may benefit most from specific treatments.

Living Well With PKD: Practical Steps

Alongside any medical treatment, everyday lifestyle measures can help protect kidney function, manage symptoms and reduce the risk of complications:

Control blood pressure: Keep blood pressure in the target range recommended by your doctor through regular home monitoring, medication adherence and dietary changes.
Moderate sodium intake: A diet lower in sodium can help manage blood pressure and, in some studies, has been associated with slower cyst growth. This is best discussed with a doctor or dietitian.
Stay well hydrated: Unless advised otherwise by your nephrologist (for example, in later-stage kidney disease), drinking sufficient water throughout the day may help suppress the hormone vasopressin, which is thought to drive cyst growth.
Protect your kidneys from added strain: Avoid regular use of NSAIDs (such as ibuprofen) and be cautious with any new medication, supplement or contrast dye, as these can place additional strain on the kidneys.
Maintain a healthy weight: A healthy body weight supports better blood pressure control and overall cardiovascular health, both of which benefit kidney health.
Avoid smoking and limit alcohol and caffeine: Smoking accelerates the decline of kidney function and increases cardiovascular risk; limiting alcohol and caffeine may also help manage blood pressure and symptoms.
Choose kidney-safe exercise: As enlarged kidneys and liver are more vulnerable to injury, contact sports and activities with a high risk of abdominal trauma are generally best avoided — low-impact exercise such as walking, swimming or cycling is encouraged and supports overall health.
Keep up with regular monitoring: Regular follow-up with a nephrologist, including periodic imaging and blood tests, allows treatment to be adjusted as the condition changes and complications to be caught early.
Look after your emotional wellbeing: A chronic, hereditary condition can bring emotional and family-planning concerns; genetic counselling, patient support groups and open conversations with family members can provide valuable support alongside medical care.