About ADPKD

What is ADPKD?

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by the growth of numerous fluid-filled cysts in both kidneys. Over time, these cysts gradually enlarge and multiply, causing progressive damage to kidney structure and function. In some patients, the disease eventually progresses to end-stage renal disease (ESRD), requiring dialysis or kidney transplantation.

ADPKD is the most common inherited kidney disease, with a worldwide prevalence of approximately 1 in 1,000 to 1 in 400. It follows an "autosomal dominant" inheritance pattern, meaning each child of an affected parent has a 50% chance of inheriting the condition.

Genetics

ADPKD is primarily caused by mutations in two genes:

• PKD1 gene (approximately 85% of cases): located on chromosome 16, it encodes polycystin-1. This form is typically more severe, with earlier onset.
• PKD2 gene (approximately 15% of cases): located on chromosome 4, it encodes polycystin-2. This form is usually milder, with slower progression.

Both proteins participate in the function of primary cilia on kidney tubule cells. Cilia act as cellular "antennae" that sense urine flow and chemical signals. Mutations disrupt ciliary function, leading to dysregulation of intracellular calcium signaling and the cAMP pathway, which ultimately promotes abnormal cell proliferation and cyst fluid secretion.

Disease Progression

ADPKD is a chronically progressive disease. In early adulthood, kidney volume may already be increasing, yet kidney function (measured by eGFR) often remains normal for many years. As cysts continue to enlarge and multiply, total kidney volume (TKV) steadily increases. Most patients develop hypertension and gradually declining kidney function between the ages of 30 and 50.

Total kidney volume (TKV) and its rate of growth are important prognostic indicators. Regular imaging to monitor TKV changes helps assess the speed of disease progression. eGFR may stay within the normal range early in the disease and only begin to decline noticeably once substantial kidney tissue has been displaced by cysts.

Common Symptoms

Symptoms of ADPKD vary widely between individuals, even within the same family. Common manifestations include:

• Hypertension — often one of the earliest signs, caused by activation of the renin-angiotensin system within cystic kidneys.
• Flank or abdominal pain — due to enlarged kidneys, cyst hemorrhage, or cyst infection.
• Hematuria — visible or microscopic blood in the urine, often from cyst rupture or kidney stones.
• Urinary tract infections — including cyst infections, which may be difficult to treat.
• Kidney stones — more common in ADPKD than in the general population.

Extrarenal Manifestations

ADPKD is a systemic disease. In addition to kidney cysts, it can affect other organs:

• Polycystic liver disease (PLD) — the most common extrarenal manifestation; liver cysts increase with age and are more frequent in women.
• Intracranial aneurysms — occur in approximately 8–10% of ADPKD patients; rupture can cause life-threatening subarachnoid hemorrhage.
• Cardiac valve abnormalities — including mitral valve prolapse and aortic regurgitation, often mild and asymptomatic.
• Other manifestations — abdominal wall hernias, diverticular disease, and pancreatic cysts may also occur.

Prognosis

The course of ADPKD is highly variable, influenced by gene type (PKD1 vs PKD2), specific mutation, and modifiable factors. Many patients progress to end-stage renal disease (ESRD) between the ages of 50 and 70, requiring dialysis or kidney transplantation. However, disease severity and timing differ significantly even among family members carrying the same mutation.

Although there is currently no cure for ADPKD, recent therapeutic advances have meaningfully improved outcomes:

• Blood pressure control with ACE inhibitors or ARBs can slow the decline of kidney function.
• Tolvaptan is the first approved drug targeting the underlying pathophysiology of ADPKD; it can slow cyst growth and the rate of kidney function decline.
• Healthy lifestyle management (low-sodium diet, adequate hydration, moderate exercise) has a positive effect on slowing progression.
• Clinical trials for several novel therapeutic targets are ongoing.

Early diagnosis, regular follow-up, and proactive management can help many patients maintain a good quality of life for a long time.

What You Can Do

While ADPKD cannot yet be cured, there is much you can do to protect your kidney function and overall health:

• Control your blood pressure — keep it within the target range recommended by your nephrologist; ACE inhibitors or ARBs are commonly used.
• Monitor regularly — attend scheduled check-ups including blood tests (eGFR, creatinine), urine tests, and kidney imaging (ultrasound or MRI) to track TKV.
• Maintain a healthy lifestyle — eat a low-sodium diet, stay well-hydrated, exercise moderately, avoid smoking, and limit caffeine and alcohol.
• Work with your nephrologist — discuss treatment options such as tolvaptan, manage comorbidities, and plan ahead for possible kidney replacement therapy.