Kidneys - polycystic kidney disease (PKD)

What is polycystic kidney disease?#

Polycystic kidney disease (PKD) is a group of chronic kidney conditions in which many cysts (fluid-filled sacs) grow in the kidneys. It is the most common inherited kidney disease and a common cause of chronic kidney disease.

If you have PKD, both kidneys are affected, although one may develop cysts earlier than the other. The cysts gradually grow, making the kidneys larger and reducing the amount of healthy kidney tissue. This makes it harder for the kidneys to work properly and can eventually lead to reduced kidney function and kidney failure. PKD affects males and females in equal numbers, and the cysts can appear at any age, depending on the type.

Simple cysts are different#

It is not unusual for people to develop simple kidney cysts as they get older – around 50% of people over the age of 50 have them. These cysts are not inherited and do not usually need treatment. This article focuses on PKD, the inherited type of cyst disease.

How PKD is inherited#

PKD is an inherited disease, which means it is passed from parents to their children. However, not everyone with PKD has a known family history.

Autosomal dominant PKD (ADPKD) is the most common inherited form. A parent with ADPKD has a 50% chance of passing the altered gene (PKD1 or PKD2), and the condition, to each of their children. If a person does not inherit the gene, their children cannot inherit it either, because the condition never ‘skips’ a generation.

Occasionally a person develops the condition with no family history. This may be due to a different inheritance pattern or a new genetic change. As with inherited PKD, that person then has a 50% chance of passing the altered gene and the disease to each of their children. Autosomal dominant PKD can lead to kidney failure.

Autosomal recessive PKD is a much less common inherited form. Signs begin in the early months of life, or even before birth, which is why it is sometimes called ‘infantile PKD’. Children born with it often develop kidney failure within a few years of birth and may have liver problems as they grow into adulthood.

Symptoms#

Autosomal dominant PKD often causes no symptoms in the early stages. The cysts usually start growing during the teenage years, and as they replace healthy tissue the outline of the kidneys can look irregular or ‘moth-eaten’. Symptoms usually develop between the ages of 30 and 40, but can begin earlier, and may include:

• high blood pressure (which may appear before the cysts do)
• pain in the back or sides
• headaches
• an enlarged and painful abdomen
• blood in the urine (hematuria)
• urinary tract infections
• kidney stones
• cysts in the liver, intestine, brain and pancreas
• abnormal heart valves
• abdominal wall hernias
• reduced kidney function or kidney failure

Autosomal recessive PKD tends to cause severe signs in affected babies, which usually leads to a prompt diagnosis. These can include:

• reduced amniotic fluid surrounding the baby in the womb
• an unusual face shape due to the lack of amniotic fluid (Potter’s facies)
• an enlarged abdomen due to enlarged kidneys, liver or spleen
• heart defects
• underdeveloped lungs
• kidney failure at birth or in the first few weeks of life

Diagnosis#

In most cases of autosomal dominant PKD there are no signs for many years, and physical check-ups or blood and urine tests do not always identify the disease. It is often picked up during investigations for other problems, such as urinary tract infections, or only once the kidneys begin to fail. Tests used to diagnose PKD may include:

• physical examination – can detect signs such as high blood pressure or enlarged kidneys
• blood tests – to assess kidney function
• urine tests – blood or protein (or both) may be found
• ultrasound – a simple, non-invasive test that can identify even quite small cysts
• genetic testing – not a routine test, but may be used for family testing; special blood tests can detect the abnormal genetic material

Genetic counseling#

If you or a family member has been diagnosed with PKD, or if PKD runs in your family, it can help to speak with a genetic counselor. These are health professionals qualified in both counseling and genetics. As well as offering emotional support, they can help you understand what PKD is, what causes it, how it is inherited, and what a diagnosis means for your health, lifestyle and future plans.

Genetic counselors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs. They can explain the genetic testing options available to you and other family members. You may choose to see one if you are planning a family, to learn your risk of passing the condition to a child, or to arrange prenatal tests.

Treatment#

There is currently no cure for PKD, but early detection and treatment can reduce or prevent some of its complications. Treatment depends on the cause and may include:

• High blood pressure – controlling blood pressure is very important; antihypertensive medication may be prescribed.
• Pain – may be due to kidney stones, bleeding, or back and kidney pain and headaches. Cysts can sometimes be drained to relieve severe back and leg pain.
• Blood in the urine – fluids, pain-relieving medication, antibiotics and bed rest may be recommended.
• Urinary tract infections – talk to your doctor about treatment with antibiotics if you get repeated or severe infections (symptoms can include frequent or painful urination and fever). An untreated infection can spread to the kidneys.
• Kidney failure – treated with dialysis, a procedure that removes waste products and extra water by filtering the blood through a special membrane.
• Kidney transplant – another option; PKD does not redevelop in the transplanted kidney.

Your doctor or healthcare professional will discuss the best choices for managing your condition.

Self-care#

Be guided by your doctor. Self-care suggestions for PKD generally include:

• changing your diet, which may help manage some symptoms – this can include reducing salt, protein, cholesterol (fats) and caffeine, but only after discussion with your doctor or dietitian, as recommendations depend on your test results
• taking part in regular, moderate physical activity
• maintaining an appropriate weight for your height
• not smoking
• avoiding non-steroidal anti-inflammatory drugs (NSAIDs) unless advised by your doctor, as they can worsen kidney function
• considering avoiding contact sports – a strong blow to the belly could injure enlarged kidneys, spleen or other organs

Key points#

• PKD is the most common inherited kidney disease and a common cause of chronic kidney disease.
• Simple kidney cysts that develop with age are different – they are not inherited and usually need no treatment.
• Autosomal dominant PKD is the most common inherited form, and a parent with it has a 50% chance of passing it to each child.
• There may be no symptoms in the early stages, and the disease is often found during tests for other problems.
• There is no cure, but early detection, treatment and self-care can reduce or prevent some complications.

Where to get help#