How is polycystic kidney disease (PKD) diagnosed?

Ultrasound is the most reliable, inexpensive, and noninvasive way to diagnose polycystic kidney disease (PKD). If someone at risk for PKD is older than 40 years and has normal ultrasound results for their kidneys, he or she probably does not have PKD. Occasionally, a computed tomography (CT) scan and magnetic resonance imaging (MRI) may detect smaller cysts that cannot be found by an ultrasound. MRI is used to measure and monitor volume and growth of kidneys and cysts.

Sometimes genetic tests might be done. This is a blood test that checks for genes that cause the disease. Genetic testing is not recommended for everyone. The test is costly, and it doesn't detect PKD in 15% of people. However, genetic testing can be useful when:
  • Imaging test results aren't clear
  • If an individual wants to donate a kidney, but there is a family history of PKD
  • A person is younger than 30 years old, with a family history of PKD, and is planning to start a family
Anjay Rastogi, MD
Several different imaging tests can be used to diagnose polycystic kidney disease (PKD). It can be diagnosed using ultrasound, which is not expensive or invasive, and there's no radiation involved. Computed tomography (CT) and magnetic resonance imaging (MRI) scans are much more sensitive. MRIs are a bit better in certain respects.

Doctors look at kidney size, along with kidney volume. Kidney size should be about 9 to 12 centimeters if you're an adult. In people with PKD, kidneys can grow up to 18, 19, 20, or even 25 centimeters in size.

Doctors look at the cysts, the contour of the kidneys and the size of the kidneys. They are all important. You can have relatively normal-sized kidneys but still have multiple cysts. There's more and more evidence that kidney size or the volume of the kidneys is a predictor of PKD outcomes. A lot of times, blood tests results remain normal to the very end, and the kidneys keep on until they collapse. When doctors do a full evaluation for kidney disease in PKD, they consider blood test results, kidney size and the number of cysts that the person has.

Genetic testing is not done routinely; however, doctors do use it when the diagnosis is not clear, especially if there is a chance that members of your family may want to be a kidney donor in the event a transplant is needed. If you had an ultrasound and a CT or MRI scan and doctors didn't find a cyst but there's still doubt, they may send you for genetic testing.

Polycystic kidney disease (PKD) is diagnosed by kidney imaging techniques. Ultrasound, computerized tomography (CT), or magnetic resonance imaging (MRI) can be used to visualize the number and size of the cysts growing in the kidneys. The imaging information, along with the person's age, kidney function, and family history of PKD, are used to confirm a diagnosis of PKD. Genetic testing can also be used to detect PKD caused by certain abnormal genes, and can provide an earlier diagnosis compared to diagnosis through imaging.

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