Autosomal dominant polycystic kidney disease (ADPKD) tends to be diagnosed in adults over 30 years of age because symptoms don't usually start before then.
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 whether it's 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 – so that the rate your kidneys are filtering your blood can be estimated
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 measure of how many millilitres (ml) of blood your kidneys are able to filter out waste products from in a minute. A healthy pair of kidneys should be able to filter more than 90ml of blood per minute.
Your GP will also arrange for you to have an ultrasound scan to look for cysts in your kidneys or other organs, such as your liver.
An ultrasound scan is a painless procedure where a small probe is passed 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, you may need to have a computerised tomography (CT) scan or magnetic resonance imaging (MRI) scan. These will show your kidneys in more detail.
An MRI scan will be recommended if you have a family history of brain aneurysms. A brain aneurysm is a bulge in one of the blood vessels in the brain that's caused by a weakness in the blood vessel wall.
Read more about diagnosing brain aneurysms.
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 because there's 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 them stress and anxiety.
Others argue that although you can't prevent ADPKD, screening can help identify cysts, and it's possible to treat the high blood pressure (hypertension) associated with ADPKD, which may reduce the person's risk of developing cardiovascular disease. If the diagnosis is known, complications won't come as a surprise and can be treated promptly and appropriately.
There's also now a treatment called tolvaptan that can slow the growth of cysts and may be beneficial in some cases.
If you're considering being screened for ADPKD, or having your children screened, you should discuss the advantages and disadvantages of screening with your GP, partner and family. You may also want to ask for a referral to see a kidney specialist.
How screening is carried out
Two methods can be used to confirm a diagnosis of ADPKD. They are:
- using an ultrasound, CT or MRI scan to check for 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, as these genetic tests are expensive and can be difficult to interpret, they're not routinely carried out at present
It's important to be aware that neither test is entirely accurate and may not always detect ADPKD, even if you have the condition.
Imaging tests may miss very small cysts in younger people and will need to be repeated later in life. Genetic testing is more sensitive and accurate in diagnosing ADPKD but may be negative in 10% of people with ADPKD.