Renal (Kidney) Disease, Brigham and Women’s Hospital
Instructor in Medicine, Harvard Medical School
Polycystic kidney disease is one of the most common inherited disorders in man. And it is the most common genetic diseases of the kidneys. We believe that about one in 500 individuals has polycystic kidney disease. In the United States, this affects about 200,000 to 600,000 people. Polycystic kidney disease is a disease that takes many, many years to develop. And many individuals don't even know that they have it unless they have a strong family history and they know about the family trait from their parents.
Cysts are the disease. There is a lot of normally functioning kidney tissue between those cysts. But as these cysts grow and expand, there is a lot of pressure that is exerted on the normal functional kidney tissue. Ultimately, the burden of cysts becomes so severe that there is not much residual functioning kidney tissue left. This happens at a late stage in the evolution of this disease.
There are two major genes that can cause polycystic kidney disease, PKD1, PKD2. PKD1 is responsible for about 85% of all polycystic kidney disease cases; PKD2, about 15%. We see, on average, the patient with the mutation in the PKD2 gene has a slower progression
Typically, we see severe limitations in kidney function at about age 55 in people with PKD1 gene mutations. Whereas those with PKD2 mutations probably lose most of their kidney function around the age of 70. Patients with polycystic kidney disease will invariably lose kidney function throughout their life at a steady pace and will later have an accelerated phase of kidney function loss. Typically, the only rescue therapy for kidney function loss is the initiation of dialysis or kidney transplantation.
Symptoms and Diagnosis of Polycystic Kidney Disease
The vast majority of patients with polycystic kidney disease experience some symptoms in their third and fourth decade of life and it invariably results in the total loss of kidney function, typically between the ages of 50 and 70, dependent on its individual form.
Typical symptoms of polycystic kidney disease are fullness and flank pain because kidneys with a large burden of cysts tend to take up a lot of space. That pushes on other organs in the abdominal cavity. Early satiety can be one of these symptoms; flank pain, occasionally; blood in the urine or, as we call it, hematuria; kidney colics; crampy pain; development of kidney stone disease; and rupture of cyst, bleeding into a cyst, or infection of cysts that have their own nature and their own acute presentation.
Since polycystic kidney disease is a genetic disease to the vast majority of patients that we see, the diagnosis is not a surprise because they have a family history of the disorder. Nevertheless, we see patients in whom we make the incidental diagnosis of polycystic kidney disease or who come for one of the manifesting symptoms, blood in the urine, flank pain, hypertension. And we typically find the presence of kidney cysts upon imaging.
Management of Polycystic Kidney Disease
We provide subspecialty counseling for patients with newly diagnosed polycystic kidney disease. Even if they have a primary care physician or a kidney specialist who is able to manage most of their problems, there are many questions that arise about genetic counseling, family implications, and long-term follow-up, maybe inclusion into therapeutic studies that we can help with here.
Up to date there are no causative treatments for polycystic kidney disease and many patients invariably run into the necessity for renal replacement therapy at some stage of their life. This can be dialysis or transplantation. We hope that future therapies will allow us to focus on the cyst progression. So, for example, that we can halt the progression of cyst growth to a degree that it will not affect people and not drive them into the necessity for kidney replacement therapy and dialysis.
Polycystic Kidney Disease Research
Our goal is to help people with PKD through many different routes. Our basic research here at the Brigham and Women's Hospital will help future generations of PKD when we learn and understand the exact cell biological and biochemical aspects of the disease. For our present patients with PKD, we are most invested in providing the best possible state-of-the art clinical follow-up, the best possible genetic counseling, and the possibility of inclusion into therapeutic trials with new drugs that may come on the market in the near future.