• At least one in every 1000 people has ADPKD
• Because ADPKD has a ‘dominant’ inheritance pattern, there is a 50% chance that an affected parent will pass on ADPKD to each child born.
• Kidneys can enlarge 3-4 times their normal size.
• Nearly 2/3 adults and 1/3 children with ADPKD will develop high blood pressure or hypertension.
• Around 1 in 12 people with ADPKD will develop small brain aneurysms (these tend to occur in those with a family history of strokes).
• No specific dietary or other lifestyle measures have been shown to prevent cysts from developing in those with ADPKD, however a healthy lifestyle will help protect your kidney function, keep your blood pressure healthy and reduce your risk of heart attacks and strokes.
• Those with ADPKD should aim to keep their daily salt intake to no more than 5/6g (1 teaspoon) and preferably less. Often foods with “low salt” on the label mean that it has been replaced by Potassium, which can be equally as harmful.
• If you have ADPKD there is a 50% chance your baby will also inherit the ADPKD gene and develop ADPKD sometime during their life.
• Around 10% of people with ADPKD also have cysts in their pancreas.
• Approximately 50% of people with ADPKD develop kidney failure before the age of 60.
Someone reports a family history of ADPKD
Signs and symptoms that commonly occur in ADPKD appear
A test is done for another reason such as UTIs or kidney stones and cysts are found in the kidneys
While no cure currently exists for PKD, there is one pharmaceutical treatment known as Tolvaptan (JINARC®), approved in Australia and available on the Pharmaceutical Benefits Scheme (PBS) for eligible patients with ADPKD.
Tolvaptan (JINARC®) is a new treatment available in Australia for adults with ADPKD (autosomal dominant polycystic kidney disease) that can help slow the progression of ADPKD. Clinical trials have shown tolvaptan can slow the rate at which your kidneys become enlarged by cysts and can help to slow the rate at which your kidney function declines.
However, in adults with ADPKD, research has discovered that vasopressin also partly contributes to the growth of kidney cysts, by making them accumulate fluid.
Tolvaptan is a specific drug that is taken twice daily as a tablet. It blocks the effect of vasopressin in the body. In ADPKD it has been shown to slow cyst growth and reduce the decline in kidney function.
To qualify for tolvaptan (JINARC®), a person with ADPKD must:
– be older than 18 years old (not pregnant or breast-feeding) and
– have reduced kidney function (i.e. Stage 2 or Stage 3 chronic kidney disease (CKD) defined as an eGFR between 30-89 ml/min/1.73 m2) and
– have evidence that the kidney function (or eGFR) is declining (This is defined as a decline in eGFR of either 5ml/min/1.73 m2in 1 year or 2.5ml/min/1.73 m2per year over 5 years) and
– Measure liver function tests on a blood test before starting the drug (see below for reasons)
It is important to note that eGFR can fluctuate slightly from day-to-day and there can also be other reasons why someone’s eGFR is declining. Your nephrologist (kidney specialist) will be able to discuss this in more detail with you and advise you if tolvaptan is suitable for you.
In the TEMPO trial, tolvaptan also slowed the growth of kidney cysts (as measured by total kidney volume in MRI scans), but follow-up studies showed that the benefit might only occur in the first 1-2 years of taking the medication. The effect of tolvaptan on the growth of kidney cysts was not investigated in the REPRISE trial.
About 5% (one in twenty) of patients on tolvaptan develop abnormalities in the blood tests to assess liver function. These are typically mild and reversible when tolvaptan is stopped, but 1 in every thousand patients can develop more serious liver injury. For this reason, patients treated with tolvaptan must have their liver function tested every month for the first 18 months after starting the medication and then every 3 months while continuing on it.
Three people in hundred treated with tolvaptan may also experience mild gout due an elevation in blood levels of uric acid.
It is important to note a significant proportion of people cannot tolerate tolvaptan due to side effects.
However, we don’t know this for sure, and especially what amount of water is needed, and this is why a clinical trial in Australia (the PREVENT-ADPKD study) is evaluating this. Some individuals drinking excessive amounts of water or other liquids can develop low blood sodium, which can be dangerous. If you are thinking of drinking large volumes of liquid this should only be done after discussion with a doctor and with ongoing supervision.
The information provided here is an overview of Tolvaptan/JINARC® and does not contain all the available information nor does it take the place of talking to your doctor or pharmacist. All medicines have risks and benefits and your doctor will weigh the risks of you taking this medicine against the benefits they expect it will have for you.