Polycystic kidney disease (PKD) killed John Greene’s grandfather at 50 and his father at 74. When Greene was diagnosed in his 40s, he ignored it at first. But after attending his father’s funeral and watching his own symptoms progress, he sought help at the Yale Inherited Kidney Disease Program.
“I came out of the first meeting feeling so good, because there just seemed to be promise,” says Greene, who asked that his real name not be used because he still has to tell his children they have a 50 percent chance of having PKD. “I’m afraid to feel too optimistic, but my creatinine has stayed the same over the last 20 months.” Creatinine is a byproduct of muscle metabolism that is used as a marker of kidney function.
Promise of a new era
Each year, Yale Medical Group nephrologists care for hundreds of patients with PKD, which can be caused by defects in one of two genes, PKD1 and PKD2. The first defect causes a common form the disease that affects one in 500 people usually diagnosed between ages 30 to 40, when they develop such symptoms as flank or back pain, or blood in the urine.
Radiologists use diagnostic ultrasound to look for cysts that can be as small as the head of a pin or as big as a grapefruit. The cysts can add pounds to the kidney’s weight, and can eventually replace the organ’s normal structure, weakening function and leading to organ failure.
Rex L. Mahnensmith, MD, clinical director of the Inherited Kidney Disease Program, and nephrologist Neera Dahl, MD, work with Stefan Somlo, MD, chief of Yale nephrology and a recipient of the Lillian Jean Kaplan International Prize for Advancement in the Understanding of Polycystic Kidney Disease, the most prestigious award for research in the field.
The three nephrologists feel they are on the edge of a new era as novel drugs entering clinical trials at Yale and other academic centers may allow them to slow the course of PKD, saving patients from kidney failure that requires treatment with either dialysis and/or kidney transplantation.
Managing the symptoms
“What we’ve known forever about PKD is that if we treat a patient’s blood pressure, we can make a big difference in the progression of the disease,” says Dahl. “If the (patient) develops a kidney stone, we can treat the kidney stone. But we haven’t been able to prevent or slow the actual disease in which the cysts continue to get bigger.”
For many patients, care still comes down to managing these symptoms, along with such others as back pain and even brain aneurysms. “One advantage we have at Yale Medical Group is that we can connect people with the various specialists they need to see,” Dahl says. She referred a patient with large PKD-related liver cysts to transplant surgeon Sukru Emre, MD, who performed a partial liver resection. The program also includes pediatric nephrology, neurosurgery, urology and genetic counseling.
Last year, Yale Medical Group nephrologists found they had a unique advantage in their ability to monitor the disease after radiologist Gary Israel, MD, adapted volumetric magnetic resonance imaging (MRI), a test previously used to assess liver volume, to measure kidney volume in PKD patients.
Making lifestyle changes
There are no large-scale studies on PKD and lifestyle, but the doctors find many patients benefit from making changes. “Rex (Mahnensmith) had all of these things that I could do that might slow down the progression of the disease,” says Greene. He now drinks three to four liters of water a day to ward off potential kidney damage, and takes fish oil for its anti-inflammatory effects.
In addition, Greene has joined a clinical trial to test a drug called Tolvaptan, which has been found to slow cyst growth in animal models. “It’s all really encouraging,” says Greene. “Hopefully, by the time my kids get to the point where they have to think about this – if they have to think about it – there will be something they can do.”