Most patients wished their nephrologist knew a little more about PKD … especially when they are first diagnosed. To help provide nephrologists a solid understanding of the basics of the disease, Dr. Theodore Steinman has put together a short primer, "Top Ten Things Every Nephrologist Should Know about PKD," patients can take to their nephrologist.
Dr. Steinman is a Clinical Professor of Medicine at Beth Israel Deaconess Medical Center and Harvard Medical School as well as a current member of the PKD Foundation Board of Trustees and a past Chair of the PKD Foundation’s Scientific Advisory Committee. Click here for a PDF document you can print and take with you to the doctor or read below ...
When interacting with your nephrologist it is important that the physician discuss issues that you and family members face with autosomal dominant polycystic kidney disease (ADPKD). Autosomal recessive PKD issues will not be addressed in this article. Your nephrologist needs to listen to you and address your concerns. The issues below are not necessarily in order of importance, but reflect an overall approach to the understanding and treatment of PKD.
1. Genetics of PKD (Incidence is 1:500 – 1000 live births)
Inherited: Each offspring of an affected parent has a 50% chance of inheriting the disease.
Spontaneous mutation: It is estimated that the incident of spontaneous mutation is 4-7% of the PKD population, but an exact number is difficult to estimate. The only way one can truly be classified as a spontaneous mutations is if both natural parents have negative ultrasounds for kidney cyst formation.
2. How do I tell if I have PKD I or PKD II ?
It is estimated that approximately 70% of the PKD population have Type I and 30% have Type II disease. There is no difference in physical appearance between those with PKD I vs those with PKD II. However, those with Type II disease have a more benign course with a smaller number of cysts, less severe hypertension and a slower time course to ESRD by approximately 15-20 years as compared to those with Type I PKD. If a family member with PKD developed ESRD before age 55, then it is likely the patient has Type I PKD. With the onset of ESRD at greater than age 70 in an affected family member, then Type II is invariably the diagnosis in the patient. Genetic blood testing, not covered by insurance, can provide the exact answer.
3. What is the natural course history of PKD (Type I and Type II) and can it be changed?
The natural course history of the two types is covered above. Results from the HALT PKD Study and the Tolvaptan Study may provide treatment options for the PKD population. The exact role of blood pressure control will be determined by the HALT PKD Study. As a general rule, blood pressure should be at least normalized in patients with hypertension who have PKD.
The role of diet remains to be determined in patients with PKD. However, we do know from the MDRD Study, that dietary protein restriction does not prevent a decline in kidney function when baseline function is < 50% of normal. If dietary protein restriction has any impact, it is in those whose kidney function is normal or near normal when the diet is instituted.
With regards to anemia management, it is recommended that the hemoglobin be maintained at the 10-12 gm/dL range. Correction of severe anemia can have a positive impact on progressive heart enlargement (a consequence of chronic kidney disease of many causes).
4. Complications of PKD – how to diagnose and manage:
Cerebral aneurysm: Screening should only be done in those patients with PKD who have a family history of a cerebral aneurysm or a stroke. Otherwise, the incidence of aneurysms is not much greater than the general population and brain magnetic resonance angiogram (MRA) is not indicated.
Heart enlargement: Enlargement of the left side of the heart (left ventricular hypertrophy) is known to occur as a consequence of chronic kidney disease and is made worse by high blood pressure. Therefore, tight control of the blood pressure and control of anemia helps reduce the severity of this heart problem.
Kidney stones: As many as 20-30% of patients with PKD have kidney stones and approximately 50% are composed of uric acid. A large fluid intake of at least two and one half quarts per day is recommended as treatment for those with kidney stones of any cause.
Hematuria: Rupture of a kidney cyst is one of the most common causes for blood in the urine. Kidney stones can also cause bleeding. With both circumstances pain is a common accompaniment. Occasionally an infected cyst that bleeds can also cause blood in the urine
5. How to manage pain in the patient with PKD:
Understanding the cause of the pain is the most important step in deciding treatment. It is important to determine if the pain is directly related to the cyst or mechanical back pain caused by the change in posture caused by cyst enlargement.
6. How do I discuss with my children and loved ones about the inheritance of PKD?
There is no clearcut answer to the question if and when children should be tested. However, the Genetic Information Non-Discrimination Act of 2008 (GINA) is a federal law that prohibits discrimination in health coverage and employment based on genetic information. This law generally prohibits health insurers or administrators from requesting or requiring genetic information on an individual or the individual’s family members. Decisions regarding coverage or rates cannot be based on genetic information. The law prohibits most employers from using genetic information for hiring, firing or promotion decisions and for any decisions regarding terms of employment. GINA’s health coverage non-discrimination protections do not extend to life insurance, disability insurance or long-term care insurance.
7. Transplantation and PKD
How to decide between a living donor and a deceased donor transplant. This is a decision that you need to discuss with the transplant team at your institution.
Short and long term success with a transplant for a patient with PKD: PKD patients do as well as any other patient with ESRD and sometimes even fare better with regard to long-term outcomes. All the statistics will be provided by your transplant team.
Do I need one or both kidneys removed prior to transplantation:
Generally kidneys do not need to be removed. However, if there is massive polycystic kidney disease that prevents placement of a kidney transplant for pure mechanical reasons, then removal of one or both kidneys may be needed. Also, if kidney cysts are repeatedly infected, then nephrectomy may be needed.
8. Polycystic liver disease – what influences the expression of this disease in one person versus another:
Cystic liver disease is more common in females who have had multiple pregnancies, generally three or more. However, it can also occur in males, but with less frequency. While kidney function is affected by cystic disease, liver function is almost never impacted in patients with polycystic liver disease. However, very enlarged livers can produce severe abdominal pain, discomfort, loss of appetite and difficulty breathing (large liver cysts press against the diaphragm).
Does polycystic liver disease occur only in patients with kidney failure:
Cysts in the liver generally occur in patients with severe polycystic kidney disease. However, a certain number of patients have massive liver enlargement, disproportionate to kidney involvement.
9. What is a healthy lifestyle in PKD?
This is the same as a healthy lifestyle in any individual. In particular, no smoking is critical. Weight control and a healthy diet are strongly recommended. Exercise should be part of one’s daily routine.
10. Current research initiatives:
Will it effect me or my children? In the last several years there have been more clinical research projects than at any time in history. All of these research initiatives are still underway and there is no clear-cut answer as to the results from the many studies that are being done. Your nephrologist should be able to keep you up to date when the results are reported from these research studies.