Polycystic kidney disease

What is it?

In polycystic kidney disease, many small sacs filled with fluid (cysts) form in the kidneys. A fault in a gene, most often PKD1 or PKD2, upsets how kidney cells grow. You are born with it, but it usually causes no problems until the cysts are big enough to affect the kidneys, most often between 30 and 40.

It is the most common inherited kidney condition, though still relatively uncommon: it is estimated that up to 1 in every 1,000 to 2,500 people in the UK has it. If one parent has the faulty gene, each child has a 1 in 2 chance of getting it. In about 1 in 10 people the gene fault is new, and they can pass it on. A rarer form, autosomal recessive PKD, needs a faulty gene from both parents and usually starts in childhood.

The first signs

When signs appear, they can include:

• pain in the tummy;
• high blood pressure;
• blood in the pee, which you may not be able to see;
• upper urinary tract infections, which can be serious;
• kidney stones.

How doctors find out

Your family doctor asks about your symptoms and family, checks your blood pressure and urine, and does a blood test to see how well your kidneys filter. A painless ultrasound scan looks for cysts in the kidneys and other organs such as the liver; sometimes a CT or MRI scan is needed. Genetic blood tests are used only in special cases. Very small cysts can be missed in young people, so a scan may need repeating later. Testing children or relatives without signs has pros and cons. If brain aneurysms run in your family, an MRI scan of the brain is recommended.

Current treatment

Blood pressure medicines (ACE inhibitors or ARBs) and less salt; tolvaptan to slow cyst growth in some adults whose kidney disease is getting worse quickly; dialysis or a transplant if the kidneys fail.

Will it get worse?

It differs a lot between people. Kidney function may slowly get worse over time. Some people reach kidney failure soon after finding out, while others keep fairly good kidneys all their life; on average about half of people need treatment for kidney failure by age 60. High blood pressure raises the risk of heart attack and stroke, and a bulging blood vessel in the brain (aneurysm) can bleed.

Medicines: what helps, and what to watch for

High blood pressure is usually treated with medicines, most often ACE inhibitors or ARBs. Tolvaptan is a tablet taken twice a day that slows cyst growth and helps keep the kidneys working for longer; it can only be used in adults who have chronic kidney disease (stage 2 or 3) at the start of treatment and signs that the kidney disease is getting worse quickly. Antibiotics treat urine infections, though infections in the cysts are harder to cure, and painkillers can ease the pain.

Good to know:

• paracetamol is the first choice for pain; painkillers such as ibuprofen (NSAIDs) are usually avoided, because they can harm the kidneys and work against blood pressure medicines;
• tolvaptan often makes you thirsty and need to pee more, also at night;
• tolvaptan has caused liver damage in some people, so at first you are monitored often through hospital clinics;

Dialysis or a transplant, for some people

Large kidney stones can be broken up with shock waves or removed with a thin tube, and large cysts can sometimes be drained. When the kidneys fail, dialysis (a machine does some of their work) or a kidney transplant are the main options. You only need one kidney to survive, so a living person can donate a kidney; close relatives usually make the best match. Some people choose care focused on comfort instead.

Is there a cure?

No, there is currently no cure. The cysts cannot be prevented, but treatment can slow their growth and manage the problems they cause.

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Sources

Written in plain words by Frontlight from these pages:

1. NHS: Autosomal dominant polycystic kidney disease (ADPKD)
2. NHS: ADPKD – Treatment
3. NHS: ADPKD – Diagnosis