“Ask Dr. HKSH” - Polycystic Kidney Disease (PKD)

Dr. LAI Kar Neng

Specialist in Nephrology

Q1.  What is polycystic kidney disease (PKD)?

Polycystic kidney disease (PKD) is a serious genetic kidney disorder. Each kidney contains about 800,000 glomeruli, and when glomeruli or renal tubules are blocked, cysts will form. PKD is characterised by multiple cysts, potentially in hundreds or thousands, that resemble a bunch of grapes. As a genetic condition with autosomal dominant inheritance, it often presents with a family history. PKD is a severe condition due to its high risk of causing kidney failure.

Q2. If neither parent has PKD, will the child be PKD-free?

PKD is primarily a genetic disorder. While 90% of patients have a family history, 10% arise due to gene mutations without a family history. There are two types of hereditary PKD. The first type affects the young to elderly people, while the second type mostly impacts those in their 60s or 70s. The second type has a lower risk of causing kidney failure, but the first is more common, and is often associated with higher risks of hypertension and kidney failure.

Q3. I have just been diagnosed with PKD. Will my PKD definitely be passed on to my children?

PKD is primarily a hereditary condition with a 50% inheritance rate, which means a 50% chance of being passed from a parent to the child. If a patient is diagnosed with PKD, doctors will carry out detailed examinations for the children. The cysts associated with PKD are often detectable on ultrasound after age 20. Therefore, children of PKD patients may have to undergo urine tests for protein and blood plus blood pressure monitoring before age 20. Once a child reaches 18 or older, an ultrasound scan will be arranged.

"Polycystic" refers to having more than 100 cysts, rather than just five or six. If an ultrasound shows no evidence of numerous cysts, we can confirm that the child concerned has not inherited the gene. It is also important to note that the gene for PKD can be tested. During pregnancy, early genetic testing can determine if the foetus carries the gene. It helps one make informed decisions about the pregnancy. This test can be conducted early to make sure the foetus is normal.

Q4. What are the symptoms of PKD?

Common symptoms of PKD include high blood pressure and impaired kidney function, while lower back pain occurs when the cysts become bigger and bigger. About 25% of patients may experience urinary tract infections or kidney stones, and there is a very small chance of developing cancer. Currently, most diagnoses of PKD are based on family history, and doctors will recommend that all family members undergo ultrasound and kidney function tests. While some patients may be asymptomatic at diagnosis, they can start treatment early.

Q5. What is the treatment of PKD?

The primary treatment for PKD is effective control of blood pressure. Over the past decade, new medications have been developed to inhibit the growth of cysts associated with PKD. Clinical studies have shown that these drugs can significantly slow down kidney decline. Ideally, treatment should commence before it comes to stage three or four, though these PKD medications are often expensive. If one fails to control the blood pressure, it should be addressed first. If blood pressure continues to rise, these specific medications should be considered.