What are the other Names for this Condition? (Also known as/Synonyms)
- ADPKD (Autosomal Dominant Polycystic Kidney Disease)
- PKD (Polycystic Kidney Disease)
- Polycystic Renal Disease
What is Polycystic Kidney Disease? (Definition/Background Information)
- Polycystic Kidney Disease (PKD) is a genetic disorder that results in the growth of numerous cysts (fluid-filled sacs) in both the kidneys, causing them to be enlarged. The enlarged kidneys eventually lead to kidney failure. Cysts may also develop in other organs too, most commonly in the liver
- There are two types of PKD:
- Autosomal Dominant Polycystic Kidney Disease (ADPKD)
- Autosomal Recessive Polycystic Kidney Disease (ARPKD)
- Mutations (alteration in the genes) in PKD1, PKD2, and PKHD1 genes cause ADPKD and ARPKD
- The major risk factor for the condition is having a parent with the disorder. Thus, a family history of Polycystic Kidney Disease increases one’s risk
- This kidney disorder presents with signs and symptoms that include abdominal pain, abdominal mass, blood in the urine, and high blood pressure
- There is no cure for the condition and PKD cannot be prevented. The treatment is directed towards managing the symptoms of the disease
- The prognosis of Autosomal Recessive Polycystic Kidney Disease is not good. Children may die in the neonatal period. However, if they survive infancy, then often a renal transplantation is required at an early age. About half of the individuals with Autosomal Dominant Polycystic Kidney Disease develop kidney failure by the age of 60 years
Who gets Polycystic Kidney Disease? (Age and Sex Distribution)
- Autosomal Dominant Polycystic Kidney Disease is the most common type of PKD (incidence of 1 in 500-1000); the symptoms usually develop between the ages of 30 and 40 years
- Autosomal Recessive Polycystic Kidney Disease is a rare type of PKD (incidence of 1 in 20,000-40,000); the symptoms typically develop soon after birth
- Polycystic Kidney Disease affects both male and female sex
What are the Risk Factors for Polycystic Kidney Disease? (Predisposing Factors)
Having a parent with this genetic disorder is the key risk factor for Polycystic Kidney Disease. Thus, a positive family history of PKD increases one’s risk.
- If one parent has Autosomal Dominant PKD, then there is a 50% chance that their child will inherit the condition
- If both parents have the gene for Autosomal Recessive PKD, then there is a 25% chance that their child will inherit the condition. In autosomal recessive form, If only one parent carries the gene, then the child will not develop Polycystic Kidney Disease
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Polycystic Kidney Disease? (Etiology)
- Polycystic Kidney Disease is an inherited genetic disorder. The inheritance pattern may be either autosomal dominant or autosomal recessive pattern
- Genetic mutations in genes PKD1 and PKD2 cause Autosomal Dominant Polycystic Kidney Disease (ADPKD type 1 and ADPKD type 2 respectively), and genetic mutations in gene PKHD1 cause Autosomal Recessive Polycystic Kidney Disease (ARPKD)
- The mutated PKD1, PKD2 and PKHD1 genes cause the production of polycystin-1 and polycystin-2 proteins, which causes the production of multiple cysts in the kidneys and other organs of the body
- ADPKD is caused by a faulty gene that is inherited from one parent, and ARPKD is caused by two faulty genes inherited from both the parents. In the autosomal recessive form, parents have no symptoms, but they still carry a recessive gene for the renal condition
- A very small percentage of Polycystic Kidney Disease cases occur randomly and the cause is not genetic; these are called acquired PKDs
Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly functioning gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.
Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children, born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).
What are the Signs and Symptoms of Polycystic Kidney Disease?
The signs and symptoms of Autosomal Dominant Polycystic Kidney Disease:
- Pain in the back or on the sides (between the ribs and hips), which is the most common symptom
- Abdominal pain (due to liver and pancreatic cysts)
- Headache that is caused by the rupture of blood vessels inside the brain
- High blood pressure
- Blood in the urine
- Urinary tract infection
- Formation of kidney stones
- Polycystic Kidney Diseases account for 5% of all kidney failure cases. The signs and symptoms of kidney failure include:
- Swollen face, ankles, feet, or hands (due to water retention)
- Shortness of breath
The signs and symptoms of Autosomal Recessive Polycystic Kidney Disease are mostly observed in children and they include:
- High blood pressure
- Urinary tract infections
- Frequent urination
- Reduced kidney function: A normal kidney function is essential for early physical development. Children with autosomal recessive forms of PKD have decreased kidney function and are usually smaller than average in size; less-than-average height and weight, when compared to other children of same age group
How is Polycystic Kidney Disease Diagnosed?
The diagnosis of Polycystic Kidney Disease may involve:
- Complete evaluation of medical history along-with thorough physical exam. A physical examination may show:
- Mass on the side of the abdomen
- Enlarged liver
- Heart murmurs (due to heart valve abnormalities)
- High blood pressure
In addition to a medical history and physical exam, the following tests may be performed:
- Blood tests
- Urine analysis
- Abdominal ultrasound: An imaging tool in which sound waves are passed through the body to create images of the kidneys
- An abdominal computed tomography (CT) scan, especially when combined with dye infusion, is one of the most sensitive tests to diagnose the disorder
- Genetic testing: If several members of the family are affected by Polycystic Kidney Disease, then genetic testing may be undertaken to determine the risk
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Polycystic Kidney Disease?
The complications of Polycystic Kidney Disease may include:
- Abnormal heart valves
- Aneurysms (bulging of the blood vessel walls due to weakening of the vessel) in the brain. This can lead to rupture and bleeding inside the brain
- Diverticulosis - the presence of small sacs in the large intestine
- Formation of liver cysts
- Abdominal wall hernias: A hernia occurs through the weakened abdominal area, whenever there is increased pressure or strain on it, like while coughing or weightlifting
- End-stage renal disease: Kidney failure occurs eventually in about 50% of the affected individuals
- Increased risk of heart attack and stroke, due to high blood pressure
How is Polycystic Kidney Disease Treated?
The treatment is focused on decreasing the progression of Polycystic Kidney Disease to kidney failure and treating the associated features of the disease such as kidney infections, kidney stones, abdominal pain, blood in urine, and high blood pressure.
- A low-salt and protein-restricted diet is recommended in case of high blood pressure or kidney failure
- Individuals with PKD should avoid contact sports, because it can result in a direct injury to the enlarged kidney and cause a rupture
- Medications, such as angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are used to control blood pressure
- In case of an infected cyst or urinary tract infections, antibiotics, such as ciprofloxacin, trimethoprim-sulfamethoxazole, clindamycin, and chloramphenicol may be administered
- Abdominal pain from enlarged kidneys: It may be treated either by using painkillers or through surgical decompression of the cyst
- Blood in the urine (hematuria) is usually due to cyst rupture or kidney stones, but it is usually self-limiting. A high intake of water and painkillers (if needed) may be recommended
- End-stage renal disease: Patients with Autosomal Dominant Polycystic Kidney Disease who progress to end-stage renal disease either require a dialysis (a machine is used to remove waste products from the body) or a kidney transplantation
How can Polycystic Kidney Disease be Prevented?
- Currently, there are no specific methods or guidelines to prevent the Polycystic Kidney Disease, since it is a genetic condition
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
What is the Prognosis of Polycystic Kidney Disease? (Outcomes/Resolutions)
- The outcome in cases of Autosomal Dominant Polycystic Kidney Disease (ADPKD) can be highly variable. Some individuals experience kidney failure soon after the condition is diagnosed, while others may lead the rest of their lives with their kidney's working relatively well
- About 50% of the individuals with autosomal dominant form of PKD develop kidney failure by the age of 60 years
- Those with ADPKD type 1 tend to develop kidney failure at an earlier age, at around 50 years; while those with ADPKD type 2, develop kidney failure at a later age, at around 70 years
- The prognosis of Autosomal Recessive Polycystic Kidney Disease (ARPKD) is typically poor. Many newborns die during the initial periods. If they survive the neonatal phase, then most often a kidney transplantation (due to renal failure) is required at an early age itself (by or before age 10)
- Polycystic Kidney Disease is generally worse in men, African Americans, and patients with sickle-cell disease
Additional and Relevant Useful Information for Polycystic Kidney Disease:
- There are many online groups available for individuals diagnosed with Polycystic Kidney Disease that provide supportive care, encouragement, and bring a measure of relief to the affected individuals and their families
- Kidney transplantation is a procedure to surgically remove a damaged or diseased kidney and replace it with a healthy kidney, from a compatible donor
The following article link will help you understand kidney transplantation: