Autosomal dominant polycystic kidney disease
Autosomal dominant polycystic kidney disease
Autosomal dominant polycystic kidney disease (ADPKD) is an inherited condition that causes small, fluid-filled sacs called cysts to develop in the kidneys.
Although children are born with the condition, ADPKD does not usually cause any noticeable problems until the cysts grow large enough to affect the kidneys' functions.
In most cases, this doesn't occur until 30-60 years of age.
When ADPKD reaches this stage, it can cause a wide range of problems, including:
tummy (abdominal) pain
high blood pressure (hypertension)
blood in the urine (haematuria) – which may not always be noticeable to the naked eye
potentially serious upper urinary tract infections (UTIs)
Eventually, kidney function gets worse and worse, until so much is lost that kidney failure develops.
What causes ADPKD?
ADPKD is caused by a genetic fault that disrupts normal development of the kidneys and causes cysts to grow.
Faults in one of two different genes are known to cause ADPKD. These are:
PKD1 – which accounts for 85% of cases
PKD2 – which accounts for 15% of cases
Both these types have the same symptoms, but they tend to be more severe in PKD1.
A baby has a 50% chance of developing ADPKD if one of its parents has the faulty PKD1 or PKD2 gene.
However, there is a different, rarer type of kidney disease calledautosomal recessive polycystic kidney disease (ARPKD), which can only be inherited if both parents carry the faulty gene. In ARPKD, problems usually start in childhood.
Who is affected
ADPKD is the most common inherited condition to affect the kidneys, although it is still relatively uncommon.
Only around one or two in every 1,000 people are born with ADPKD, which means there are currently around 60,000 people in the UK with the condition.
How ADPKD is treated
There is currently no cure for ADPKD, but various treatments are available to manage problems caused by the condition.
Most problems – such as high blood pressure, pain and UTIs – can be treated with medication, although you may need to have an operation to remove any large kidney stones that develop.
If the condition reaches a point where the kidneys are not able to function properly, there are two main treatment options:
dialysis – where a machine is used to replicate kidney functions
kidney transplant – where a healthy kidney is removed from a living or recently deceased donor and implanted into someone with kidney failure
The outlook for ADPKD is highly variable. Some people experience kidney failure soon after the condition is diagnosed, whereas others may live the rest of their life with their kidneys working relatively well.
On average, around half of people with ADPKD require treatment for kidney failure by the time they are 60.
As well as kidney failure, ADPKD can also cause a number of other potentially serious problems, such as heart attacks and strokes caused by high blood pressure, or bleeding on the brain (subarachnoid haemorrhage) caused by a bulge in the wall of a blood vessel in your brain (brain aneurysm).
ADPKD causes multiple cysts to develop in the kidneys
The kidneys are two bean-shaped organs that are located on either side of the back of the body, just underneath the ribcage.
The main role of the kidneys is to filter out waste products from the blood and pass them out of the body as urine.
The kidneys also play an important role in:
helping to maintain blood pressure at a healthy level
keeping salt and water in balance
making hormones needed for the production of blood and bone
Symptoms of autosomal dominant polycystic kidney disease
The symptoms of autosomal dominant polycystic kidney disease (ADPKD) are caused by the growth of fluid-filled sacs (cysts) in the kidneys.
Although the condition is present from birth, ADPKD may not cause any obvious problems until the cysts have reached a size where they significantly affect how well your kidneys work. In most cases, this doesn't happen until 30-60 years of age.
The growth of these cysts can eventually cause your kidneys to increase in size. In some cases, the kidneys of older adults with ADPKD can be three or four times larger than those of adults who don't have the condition.
What problems can ADPKD cause?
The growth of cysts in your kidneys can cause a wide range of problems, including:
pain in your tummy (abdomen), side or lower back
blood in your urine (haematuria)
high blood pressure (hypertension)
recurrent urinary tract infections (UTIs)
eventually, loss of kidney function – known as chronic kidney disease (CKD)
These problems are described in more detail below.
Pain in the abdomen, side or lower back is often the first noticeable symptom of ADPKD. This can be severe, but is usually short-lived – lasting from a few minutes to several days.
Common causes of pain associated with ADPKD include:
a cyst becoming larger
bleeding into one or more cysts
a kidney stone getting stuck in your kidney
a kidney or other part of your urinary system, such as your bladder, becoming infected – these are known as UTIs
Blood in your urine
Blood in your urine can be another common initial symptom of ADPKD. Although this can often be a frightening symptom, it is not usually a serious concern because most cases will resolve within a week without the need for treatment.
However, it is still important to see your GP if you notice blood in your urine so another cause, such as a growth in the bladder, can be looked for and excluded.
High blood pressure
High blood pressure is considered by many experts to be the first effect of ADPKD, and it can affect some children with the condition.
However, high blood pressure does not usually cause any obvious symptoms and is only usually detected during routine testing.
Symptoms only occur when it reaches a very high level, which is rare. In such circumstances, symptoms can include:
a persistent headache
blurred (double) vision
shortness of breath
If there are any symptoms to suggest that it may be uncontrolled, you should see your GP urgently.
Having ADPKD puts you at increased risk of developing kidney stones.
Smaller kidney stones may pass out of your kidneys without causing any symptoms, but larger stones can get blocked in your kidney or ureter (the tube that connects your kidney to your bladder) and cause problems such as:
intense pain in the back or side of your abdomen, or occasionally in your groin – the pain may last for minutes or hours, with pain-free intervals in between
feeling restless and unable to lie still
needing to urinate more often than normal
blood in your urine
You should contact your GP if you think you have a kidney stone, so they can try to find out what is causing your symptoms.
Urinary tract infections (UTIs)
UTIs are broadly classified into one of two groups – lower UTIs and upper UTIs.
A lower UTI is an infection that develops in your bladder or urethra (the tube that carries urine out of the body). An upper UTI is an infection that develops in your kidneys or your ureters (the tubes that link your kidneys to your bladder).
ADPKD does not increase your risk of developing lower UTIs such as bladder infections (cystitis), but can mean that any lower UTIs you do develop could spread to the kidneys and become potentially serious upper UTIs.
The symptoms of a lower UTI can include:
a need to urinate more frequently, either during the day or night, or both
pain or discomfort when passing urine
an urgent need to urinate (holding in your urine becomes more difficult)
unpleasant smelling urine
The symptoms of an upper UTI can include:
a high temperature (fever) of 38C (100.4F) or above
You should visit your GP if you have ADPKD and you think you may have a UTI, because it may need treatment to stop the infection spreading into the cysts in your kidneys.
Chronic kidney disease (CKD)
Most people with ADPKD will eventually lose a significant amount of kidney function. Loss of kidney function caused by kidney damage is known as chronic kidney disease (CKD).
CKD does not usually cause symptoms until it has reached an advanced stage, known as CKD stage 4 (when 75% of kidney function has been lost).
The most advanced stage of CKD (stage 5) is called kidney failure or end-stage renal disease. This is when dialysis is essential to keep the person alive. Symptoms of kidney failure include:
poor appetite and weight loss
swollen ankles, feet or hands
shortness of breath
an increased need to urinate, particularly at night
in men, erectile dysfunction
in women, absent periods (amenorrhoea)
Kidney failure rarely happens suddenly, and treatment options should have been discussed and a treatment plan chosen before this stage has been reached.
Causes of autosomal dominant polycystic kidney disease
Most cases of autosomal dominant polycystic kidney disease (ADPKD) are caused by a mutation in the genetic building blocks (DNA) of either the PKD1 or PKD2 genes.
In ADPKD, the faulty PKD1 and PKD2 genes causes some of the cells in the kidneys to reproduce abnormally, which causes cysts to form.
In most cases of ADPKD, the faulty gene is passed to a child by one of the parents. A child of a parent with ADPKD has a 50% chance of inheriting the faulty gene.
In around one in four cases of ADPKD, a person develops the condition without having a known family history of the condition.
This could be because the condition was never diagnosed in a relative, or a relative with the condition may have died before their symptoms were recognised.
In around 1 in 20 of ADPKD cases, the mutation develops for the first time in the affected person. It is not known what causes this to happen.
The affected person can then pass the faulty gene on to their children in the same way as someone who inherited it from one of their parents (see above).
Diagnosing autosomal dominant polycystic kidney disease
Autosomal dominant polycystic kidney disease (ADPKD) tends to be diagnosed in adults aged over 30 because symptoms don't usually develop until this stage.
When making a diagnosis, your GP will ask about your symptoms and your family’s medical history. If your kidneys are enlarged, your GP may be able to feel them in your tummy (abdomen).
Your GP may also arrange for some of the tests described below to be carried out.
Urine and blood tests
Your GP will measure your blood pressure to see if it is higher than normal. They may also carry out other tests, such as:
urine tests – to check for blood or protein in your urine
blood tests– to allow an estimate of the rate that your kidneys are filtering your blood to be made
GFR blood test
An effective way of assessing how well your kidneys are working is to calculate your glomerular filtration rate (GFR). GFR is a measurement of how many millilitres (ml) of blood your kidneys can filter out waste products in a minute. A healthy pair of kidneys should be able to filter more than 90ml per minute.
It is difficult to measure GFR directly, so it is estimated using a formula. The result is called the estimated GFR or eGFR. Calculating your eGFR involves taking a blood sample and measuring the levels of a waste product called creatinine, taking into account age, gender and ethnic group.
If your creatinine levels are higher than normal, it suggests your kidneys may not be filtering the blood as effectively as they should be. A low eGFR rate (15-29ml per minute) would suggest your kidneys are failing. At an eGFR of less than 10ml per minute, renal replacement treatment with dialysis or kidney transplantation is needed.
Your doctor will also arrange for you to have an ultrasound scan to look for cysts in your kidneys or other organs, such as your liver.
This is a painless procedure that involves passing a probe across the skin over your kidneys. The probe emits high-frequency sound waves that are used to create an image of the inside of your body.
In some cases, your doctor may arrange a computerised tomography (CT) scan or a magnetic resonance imaging (MRI) scan for you. These show the kidney in more detail.
If you have a family history of brain aneurysms, you will be advised to have a MRI scan. A brain aneurysm is a bulge in one of the blood vessels in the brain that is caused by a weakness in the blood vessel wall.
Screening people known to be at risk of developing ADPKD due to a family history of the condition is a controversial issue in the medical community.
Some argue that screening achieves little, as there is currently no treatment to stop ADPKD developing.
Telling a person that they have ADPKD and are likely to develop kidney failure later in life could also cause a lot of stress and anxiety.
Other experts argue that although you can't prevent ADPKD, you can treat the high blood pressure (hypertension) associated with the condition, which may reduce the person's risk of developingcardiovascular disease. If the diagnosis is known, complications will not come as a surprise and can be treated promptly and appropriately.
If you are considering being screened for ADPKD, or are considering having your children screened for the condition, discuss the advantages and disadvantages of screening with your GP, partner and family.
How screening is performed
There are two methods used to confirm a diagnosis of ADPKD. These are:
using an ultrasound, CT or MRI scan to check for any kidney abnormalities
in special circumstances, using genetic blood tests to determine whether you have inherited one of the genetic faults known to cause ADPKD in your family – however, these genetic tests are very expensive and can be difficult to interpret, so are not routinely performed
However, it's important to be aware that neither test is entirely accurate and they may not always detect ADPKD, even if you do have the condition..
Treating autosomal dominant polycystic kidney disease
Although there are some potentially useful medications that can reduce the growth rate of cysts, there is currently no treatment that can cure autosomal dominant polycystic kidney disease (ADPKD) or stop cysts forming in the kidneys.
However, treatment is available to help manage the various problems the condition can cause, such as high blood pressure (hypertension), pain and kidney stones.
If you are diagnosed with ADPKD, you will usually see a kidney specialist, who can help draw up a suitable treatment plan.
This plan will also include what you would want to do if your kidneys stopped working sufficiently (known as kidney failure).
Some of the main treatments are described below.
High blood pressure
High blood pressure in people with ADPKD is usually treated with medication. The two medications most widely used are angiotensin-converting enzyme (ACE) inhibitors and angiotensin-2 receptor blockers (ARBs).
There are also some lifestyle changes you can make to help reduce your blood pressure, such as cutting your salt intake to less than 6g (0.2oz) a day. 6g of salt is about one teaspoonful.
In many cases of ADPKD, any pain you experience can be relieved by treating the underlying cause, such as kidney stones or a urinary tract infection (UTI).
If you need to take a painkiller, paracetamol is the best medication to try first. If your pain is particularly severe, you may be prescribed a stronger painkiller, such as codeine or tramadol.
Your doctor will usually recommend avoiding a non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen, because they could disrupt kidney function and interfere with medications prescribed to control your blood pressure. However, a short course of NSAIDs may sometimes be safe for people with well controlled blood pressure and relatively normal kidney function.
If you have long-term (chronic) pain, you may be prescribed antidepressants or anticonvulsant medications (which are normally used to treat epilepsy), as these can also relieve some types of pain.
Occasionally, draining large cysts can be performed to relieve the pain caused by the increased pressure.
Small kidney stones pass out of your body when you urinate. If needed, you may be given a strong painkiller and medication to stop you feeling sick or vomiting. Making sure you drink plenty of water, which will increase the flow of urine, can also help by flushing the stone into the bladder.
If a kidney stone is too big to be passed naturally, you may need to have treatment to remove it. Possible treatment options include:
using energy waves to break the stone into smaller pieces – this is known as extracorporeal shock wave lithotripsy (ESWL)
passing a thin telescopic instrument called a ureteroscope up your urethra (the tube that carries urine out of body) to remove or break up the stone
Urinary tract infections (UTIs)
UTIs can often be treated with a course of antibiotic tablets lasting 7-14 days.
Drink plenty of fluids while you are waiting for the antibiotics to take effect, as this will help relieve symptoms of a high temperature. Paracetamol can be used to relieve pain.
It's important to see your doctor as soon as possible if you developsymptoms of a UTI, as it could spread to the cysts in your kidneys if left untreated.
Infection in the cysts is harder to cure, because it can be difficult for the antibiotics to penetrate them. If the infection persists despite antibiotic treatment, the infected cysts may need to be drained during surgery or with a needle inserted through your skin.
In severe, persistent or frequently recurring cases, having surgery to remove one or both of your kidneys – followed by dialysis or a kidney transplant (see below) – may be recommended.
You will have blood tests at varying intervals to check your kidney function. You should discuss with your doctors how you would like to be treated if your condition reaches a stage where your kidneys stop working altogether (kidney failure).
The two main treatment options for kidney failure are:
dialysis – where a machine replicates some of your kidneys' functions
kidney transplant – where a kidney is removed from a donor and implanted into a patient
A kidney donor can be somebody who is recently deceased or, as is increasingly common, someone who is still alive and wants to donate one of their healthy kidneys.
A person only needs one kidney to survive. Therefore, unlike other types of organ donation, a living person can donate a kidney. Close relatives usually make the best match, so you may want to ask your relatives if they would consider having themselves tested to see if they are a suitable donor.
A few people with kidney failure decide against having either dialysis or kidney transplants, preferring simple treatment of their symptoms. They may, for example, choose this option if it is unlikely that dialysis will significantly prolong their life or improve its quality. If this choice is made, supportive treatment to help control symptoms is provided to make the end of life as comfortable as possible.
Complications of autosomal dominant polycystic kidney disease
Autosomal dominant polycystic kidney disease (ADPKD) can sometimes lead to potentially serious complications in other parts of the body besides the kidneys.
Some of the main complications associated with ADPKD are described below.
Many people with ADPKD develop cysts in other organs, in addition to their kidneys. One of the most common organs also affected by ADPKD is the liver.
These cysts do not usually disrupt normal liver functions, but they can sometimes become infected and/or cause symptoms such as:
swelling and bloating of your tummy (abdomen)
in rare cases, jaundice (yellowing of the eyes and skin from liver damage)
In most cases, the symptoms will pass without the need for treatment. In rare cases, when a larger cyst causes severe and/or persistent pain, surgery may be required to drain the cyst.
In very rare cases, the liver becomes so massively swollen that it stops working properly. It may be necessary to surgically remove some of the liver or perform a complete liver transplant.
As a result of high blood pressure, people with ADPKD also have an increased risk of developing cardiovascular disease (CVD).
CVD is a general term to refer to conditions that affect the heart and blood vessels, and includes:
coronary heart disease – where the supply of blood to the heart becomes restricted
stroke – when the blood supply to part of the brain is blocked, damaging it irreversibly
heart attack – when the supply of blood to the heart is suddenly blocked, causing irreversible damage to the heart muscle
If you are at risk of CVD, you may be prescribed low-dose aspirin to help stop your blood clotting, and a medication called a statin to reduce your cholesterol levels.
Making healthy lifestyle changes can also help reduce your risk of CVD, such as stopping smoking, reducing your alcohol intake, exercising regularly and eating a healthy diet.
An aneurysm is a bulge in a blood vessel caused by a weakness in the blood vessel wall. As the blood passes through the weakened part of the vessel, the blood pressure causes it to bulge outwards like a balloon.
Brain aneurysms are more common in people with ADPKD than those in the general population, probably due to the high blood pressure affecting the weakened blood vessel walls.
A brain aneurysm does not usually cause any noticeable symptoms unless it bursts (ruptures). The ruptured aneurysm then causes bleeding over the surface of the brain. This is known as a subarachnoid haemorrhage.
Symptoms of a subarachnoid haemorrhage can include:
a sudden agonising headache – which is often described as being similar to a sudden hit on the head, resulting in a blinding pain unlike anything experienced before
feeling and being sick
sensitivity to light (photophobia)
blurred or double vision
stroke-like symptoms – such as slurred speech and weakness on one side of the body
loss of consciousness or convulsions (uncontrollable shaking)
A subarachnoid haemorrhage is a medical emergency that requires immediate treatment to prevent serious complications, brain damage and death. Call 999 immediately and ask for an ambulance if you think that you or someone you know is having a subarachnoid haemorrhage.
It is estimated that around 10% of people with ADPKD will develop a brain aneurysm, but most won’t have any symptoms and will never cause a problem. Those people who also have a family history of subarachnoid haemorrhages are at greater risk.
If you have ADPKD and have a family history of subarachnoid haemorrhages, you will usually be offered a magnetic resonance imaging (MRI) scan to check for aneurysms in your brain. If no aneurysm, or only small ones, are found you will be offered further scans at intervals of one to five years to check for the development of new ones or an increase in the size of an existing one.
If an aneurysm of a particular size is detected and your doctor thinks there is a risk it could rupture in the future, they may recommend having an operation or procedure to prevent this.