What Is Polycystic Kidney Disease? Causes, Types, Symptoms, and Treatments
Whether you've been recently diagnosed with polycystic kidney disease (PKD), or have lived with it for years, there's no doubt that this condition can be overwhelming. The good news is, with early diagnosis and treatment, much of the damage associated with it can be prevented.
Here's what you should know to live your best life with PKD.
What is polycystic kidney disease—and what causes it?
Polycystic kidney disease is a form of chronic kidney disease. "It's actually a genetic disorder that causes kidney cells to mutate and change into cysts," explains Uday Nori, MD, a kidney specialist at the Ohio State University Wexner Medical Center in Columbus, Ohio. "As these cysts grow bigger and bigger, they compress the healthy tissues that surround them. This slowly damages your kidneys, lowering kidney function and ultimately leading to kidney failure."
With PKD, people develop multiple fluid-filled cysts in their kidneys, which can cause other problems, too, like high blood pressure and cysts in your liver, pancreas, spleen, ovaries, and bowels, says the National Kidney Foundation (NKF). Polycystic kidney disease may affect the brain, and lead to an aneurysm, or burst blood vessel that could turn into a life-threatening stroke. It can also cause a heart murmur, since it can make your heart valves floppy, the NKF points out.
About 600,000 people in the US have PKD. It's the fourth leading cause of kidney failure, responsible for around 5% of all cases, says the NKF.
"It's an equal opportunity disease that affects men and women of all different races and ethnicities," Dr. Nori adds.
What are the types of polycystic kidney disease?
Polycystic kidney disease is genetic, says the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). This means it's passed to you from either your mother or father through genes.
There are two main types of PKD:
Autosomal dominant polycystic kidney disease (ADPKD)
About 90% of polycystic kidney disease cases are ADPKD, and this form affects anywhere from 1 in every 400 to 1 in 1,000 people worldwide, says NIDDK. It's passed to you from either your mom or dad by something called dominant inheritance. That means you need only one copy of the abnormal gene to cause the disease. Every child of a parent with that gene has a 50% chance of getting ADPKD, says the NKF.
Autosomal recessive PKD (ARPKD)
This type of PKD is passed from parent to child by recessive inheritance. That means both parents need to carry the abnormal gene, and both need to pass it on to their child. (Unlike ADPKD, that means every child of these parents has a 25% chance to get ARPKD). Since it's recessive, it's much rarer: it only affects about one in 20,000 people worldwide, notes NIDDK. But it's much more severe: "unfortunately, most babies diagnosed with it don't live into adulthood," says Dr. Nori.
What are the symptoms of polycystic kidney disease?
The symptoms of autosomal dominant polycystic kidney disease don't show up until adulthood—usually between the ages of 30 and 40, says the NKF.
"Patients don't usually notice signs until the cysts are at least a half inch in size," explains Richard Glassock, MD, professor emeritus at the David Geffen School of Medicine at UCLA and past president of the NKF and the American Society of Nephrology.
According to the NKF, symptoms include:
- High blood pressure. This is the most common sign, although you might not know you have it unless you're screened for it, since it's often symptomless.
- Heart flutters. About 25 percent of people with polycystic kidney disease have a "floppy" valve, which can cause a fluttering or pounding feeling in your chest. These symptoms go away on their own, but may come back periodically.
- Back or side pain.
- Frequent headaches
- Blood in your urine
- Frequent bladder or kidney infections
- Loss of appetite
Autosomal recessive polycystic kidney disease is often now diagnosed prenatally. According to NIDDK, signs on a fetal ultrasound include:
- Enlarged kidneys. This puts pressure on your baby's lungs, making it harder for them to breathe.
- Growth failure. During your pregnancy, ultrasounds may reveal your baby is growing smaller than normal because of decreased lung and kidney function.
- Low amniotic fluid. Since your baby has decreased kidney function, they produce low levels of amniotic fluid which can cause breathing problems in the womb.
NIDDK says signs of recessive polycystic kidney disease in infancy include:
- Trouble breathing. Babies with severe ARPKD may die hours or days after birth due to poorly developed lungs.
- Kidney failure.
- Liver scarring. This can usually be seen even at birth, but gets worse over time.
- High blood pressure.
How is polycystic kidney disease diagnosed?
If you have a family history of either type of polycystic kidney disease, it's important to get tested for it. "Many people don't want to, since there's no cure for it, but the sooner you know, you can take steps to try to prevent the disease from progressing," says Dr. Nori.
Your doctor can refer you to a geneticist, a physician who specializes in genetic diseases that are passed down through families. They'll check your blood and/or your saliva for the gene mutations that cause polycystic kidney disease. If you do have the gene mutation, you'll need to be followed closely by a kidney specialist. They may periodically do tests like ultrasound or CT scans to check for cysts in your kidneys. Once they develop, they can do magnetic resonance imaging (MRI), a test that uses radio waves to provide detailed images of the cysts, their size, and how fast they're growing.
"Unfortunately, there's no way to prevent polycystic kidney disease," says Dr. Glassock. "But if a patient knows they have it, there's a lot they can do to keep it under control."
What is the treatment for polycystic kidney disease?
There's no cure for polycystic kidney disease. But there are things you can do to slow its progression. They include:
Get your blood pressure under control. The higher your blood pressure, the higher your likelihood of developing kidney failure, explains Dr. Nori. Two types of blood pressure medications, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), can lower blood pressure in most people with PKD, while also helping to improve kidney function, per NIDDK.
Watch your diet. You'll need to follow a kidney-friendly diet, which means you'll want to hold the salt shaker, load up on fruits and veggies, and drink plenty of water, says Erin Rossi, RD, a nutritionist who specializes in kidney disease at the Cleveland Clinic. While you may have heard that people with kidney disease need to limit the amount of protein they eat, you'll still need some protein: usually around 0.8 grams per kilogram of body weight (so if you're 150 pounds, you'll need around 55 grams of protein each day). Focus on higher quality animal proteins that are easy for your kidneys to break down, like meat, poultry, fish and eggs, advises Rossi.
Tolvaptan. This drug, which was approved by the US Food and Drug Administration in 2018, is a type of drug called a vasopressin receptor antagonist and has been shown to slow the decline in kidney function and reduce pain symptoms in people with ADPKD, says the Polycystic Kidney Disease Foundation. Side effects include peeing a lot, especially at night, and feeling thirsty. You'll also need to be monitored closely by your doctor, since the drug can rarely affect liver function (and the effects are reversible once it's stopped).
Dialysis or kidney transplant. If you have end-stage kidney disease, then you'll require one of these options, says Dr. Glassock. The best form of dialysis for people with PKD is hemodialysis, where a dialysis machine is used to clean your blood. (In fact, people with PKD who have hemodialysis survive longer than people with other types of end-stage kidney disease.) A kidney transplant may also be an option; it's something you'll want to discuss with your doctor, says the PKD Foundation.
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