Polycystic Kidney Disease (PKD)
Polycystic kidney disease causes fluid-filled sacs called cysts to grow in the kidneys. The cysts can become large and cause scarring, which eventually harms the organs’ function. This disease is caused by a gene mutation, usually passed down by a parent.
While symptoms often first appear in young adulthood, polycystic kidney disease, or PKD, usually progresses slowly and variably in different patients. About half of patients with PKD will eventually have kidney failure, and will need kidney dialysis or a transplant.
“It usually takes more than five decades for individuals to progress to that degree of kidney injury,” says Stefan Somlo, MD, chief of nephrology at Yale Medicine.
What are the symptoms of polycystic kidney disease?
People with polycystic kidney disease may develop high blood pressure as a first symptom. This can occur even before cysts are visible in the kidneys. Other early symptoms may include flank pain along the sides of the lower back.
“It can either be very acute or a more chronic aching,” says Dr. Somlo. Some patients report a feeling of fullness in the same area and may have blood in their urine.
Recurring urinary tract infections (UTIs) in young men may also suggest polycystic kidney disease. People with polycystic kidney disease are also more prone to kidney stones.
In addition, polycystic kidney disease is associated with the development of cysts in the bile ducts of the liver. “While the liver function remains intact, in some patients the liver can grow to such a degree that it creates discomfort,” Dr. Somlo says.
Some people with a PKD mutation may also have increased risk of aneurysms in the brain.
How is polycystic kidney disease diagnosed?
Polycystic kidney disease is typically diagnosed using imaging studies, such as ultrasound, which will show the cysts in the kidneys. A genetic test, performed on a blood sample, can detect the gene mutations that cause the disease.
What can cause polycystic kidney disease?
Polycystic kidney disease is almost always caused by mutations in one of two genes, called PKD1 and PKD2. These are different genes, situated on different chromosomes, but they are believed to work together.
These mutations can occur randomly in any newborn, so they affect populations across the world at similar rates. But once a mutation occurs in an individual, it can be inherited by his or her offspring. “An affected parent has a one in two chance of passing it on to each of his or her children,” says Dr. Somlo.
Many patients at risk for inherited kidney disease know of their predisposition, usually because their parent or sibling has already been diagnosed with it. These patients may start seeing a doctor for monitoring before symptoms develop. But a small subset will be the first in their family to have the mutation, which doctors call a “de novo” mutation. Their disease is typically discovered when they start to have symptoms.
What are the treatment options for polycystic kidney disease?
There are now no ways to correct the mutations that cause polycystic kidney disease, so physicians focus on addressing their consequences.
“These include hypertension (high blood pressure), which needs to be managed aggressively,” says Dr. Somlo.
Pain from the cysts can be managed with pain relievers. Physicians usually start with options such as acetaminophen or nonsteroidal anti-inflammatories (NSAIDs) but may prescribe other types if necessary. Cysts can also be drained via a needle through the skin.
If the kidneys begin to fail—which only occurs in some patients—the patient should be cared for by a nephrologist.
“Some patients will progress to end-stage kidney disease,” Dr. Somlo says. “At this point, the kidneys do not provide adequate function, and these patients will require either dialysis or transplantation.”
What makes Yale Medicine’s approach to treating polycystic kidney disease unique?
The Yale Medicine Chronic Kidney Disease Program offers patients the opportunity to receive care from nephrologists, liver disease experts, aneurysm experts and geneticists who can explain the nuances of inherited disorders to patients and skillfully manage the illness.
Yale Medicine offers opportunities for patients with polycystic kidney disease to take part in clinical trials to better explain the disease and to evaluate new treatment approaches. The experts at Yale Medicine also continue to study the mechanisms underlying the cyst formation.
“We hope these studies will lead to the development of therapies,” Dr. Somlo says. “We focus on research that we can translate into the care of our patients.”