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Introduction   

Polycystic kidney disease (PKD) is a chronic medical condition diagnosed in children and adults. There are two types, autosomal dominant and autosomal recessive. It is important for nurses to understand the signs and symptoms of PKD, treatment, and potential complications. This course aims to equip learners with knowledge related to PKD by reviewing the definition, epidemiology, and pathophysiology of the disease. Signs and symptoms, treatment, and complications will also be discussed. Lastly, this course will review patient and family education.

Polycystic Kidney Disease: The Basics 

This section addresses the definition of polycystic kidney disease, normal kidney functioning, and tests for diagnosis. 

Definition 

Polycystic kidney disease is a type of chronic kidney disease (CKD) that is inherited. It occurs when cysts filled with fluid form in the kidneys. As more cysts begin to form and grow, kidney function begins to decrease over time and can eventually lead to kidney failure. There are two types of PKD – autosomal dominant (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) [8]. Autosomal dominant PKD is the more common of the two and is the most common genetic cause of kidney failure worldwide [5]. This type of PKD is typically diagnosed in adulthood, while the autosomal recessive type is diagnosed shortly after birth or in the womb [8]. 

Normal Kidney Function 

In general, kidneys work by filtering the blood and removing any waste and excess water to make urine. The kidneys also help with balancing the body’s fluid and electrolytes, such as sodium, calcium, potassium, and phosphorus. Additionally, kidneys play a vital role in blood pressure control and red blood cell production [9]. 

Located in the kidneys are millions of tiny filtering units that filter the blood, called nephrons. Each nephron contains a glomerulus (which acts as a blood filter) and a tubule, which collects urine after the glomerulus has filtered it. The tubule removes excess products or waste that the body no longer needs and returns any needed substances back into the bloodstream [9]. 

Blood flows from the renal artery, enters the nephron, and then is first filtered through the glomerulus. The glomerulus filters out small molecules, like water and minerals. The larger molecules are not filtered and stay in the bloodstream, like protein and blood cells [9]. 

After the smaller molecules are filtered through the glomerulus, they enter the renal tubule. The tubules remove any excess molecules that the body does not need. The molecules the body needs are reabsorbed through the tiny blood vessels that run alongside the renal tubule. These tiny blood vessels converge and leave the kidney through the renal vein. Any excess waste left in the tubules becomes urine [9]. 

Diagnostic Tests 

To check a person’s kidney function, a glomerular filtration rate (GFR) blood test is typically completed. A normal GFR is 60 or higher. Anything below 60 can indicate kidney disease and anything 15 or lower indicates kidney failure. Other blood tests can be completed, like a protein urine test and microalbumin creatinine ratio test. Protein and albumin in the urine can be some of the first signs of kidney disease. Also, a person’s blood urea nitrogen (BUN) levels may be high in kidney disease, as this measures the kidneys’ waste products in the bloodstream [6].

Epidemiology/Statistical Evidence 

In the United States (U.S.), around 500,000 people are affected by PKD [8]. Autosomal dominant polycystic kidney disease is a genetic disorder, affecting about one in 1000 live births [12]. Autosomal recessive polycystic kidney disease occurs in about one in 20,000 people [8]. A research study published in 2021 found that the prevalence of Americans diagnosed with autosomal dominant PKD was 42.6 per 100,000 people between the years 2022 and 2018 [1]. 

A three-year research study conducted in the U.S. from 2013 to 2015 found that females were almost twice as likely to be diagnosed with autosomal dominant PKD in early adulthood. The research study reviewed data from Truven Health Market Scan Claims and the National Ambulatory Medical Care Survey. Females may have been more likely to be diagnosed in early adulthood due to the use of ultrasound during child-bearing years. The study also found that males were more likely to be diagnosed at the age of 65 years or older and a diagnosis of the autosomal dominant type occurred for males after it developed into chronic kidney disease [14]. On the other hand, autosomal recessive PKD appears to affect both males and females equally [3].  

Another research study conducted from 2022 through 2018 in the U.S. found that the incidence of autosomal dominant PKD was 42.6 per 100,000 people. This same study discovered that the prevalence of this type of PKD was increased in Blacks at 73.0 per 100,000 and non-Hispanic whites at 63.2 per 100,000 people. Asian and Hispanic people had a lower risk compared to the prior at 48.9 and 39.9 per 100,000 people, respectively [1]. Regarding autosomal recessive PKD, there is not an increased risk regarding certain genders or racial groups [11].

Pathophysiology of Polycystic Kidney Disease 

As mentioned, PKD is an inheritable medical condition. It can be either autosomal dominant or autosomal recessive. Autosomal dominant PKD is caused by a genetic mutation on either the PKD1 gene on chromosome 16 or the PKD2 gene on chromosome 4. PKD1 codes for protein polycystin 1, while PKD2 codes for polycystin 2 [12]. The PKD1 expression is more common and is around 85% of cases, while PKD2 expression accounts for the remaining 15% of autosomal dominant PKD cases [11]. Polycystin 1 regulates renal tubular epithelial cellular adhesion and polycystin 2 aids with ion channel functioning. Any mutations in these genes and proteins can alter the renal tubule cells and fluid secretions, slowing tubular flow. This causes cysts to eventually form due to renal tubular dilation and slowed glomerular filtration. Vasopressin stimulates cell growth, which can lead to an increased number and size of cysts forming [2]. 

Alternatively, autosomal recessive PKD is caused by a genetic mutation on the PKHD1 gene on chromosome 6p12. This mutation causes epithelial cells lining the renal tubules to proliferate abnormally. Thus, leading to loss of normal physiological function, increased fluid secretion, and cyst formation [11]. 

Clinical Presentation 

Diagnosis of autosomal dominant PKD versus autosomal recessive PKD can look different since the dominant type is typically diagnosed in adulthood, while the recessive type is diagnosed inside the womb or shortly after birth. Thus, nurses must recognize and understand the potential signs and symptoms of both types.  

Signs and Symptoms of Autosomal Dominant PKD  

Signs of autosomal dominant PKD typically include: 

• Hypertension 

• Hematuria 

• Flank Pain 

• Urinary Tract Infections 

People with this type of PKD also tend to have hepatic cysts and abdominal masses since the mutations in the PKD1 gene affect other body organs as well. Patients may also have renal failure, kidney stones, or renal cancer. Hypertension is typically the earliest clinical presentation of this type of PKD [5].  

Signs and Symptoms of Autosomal Recessive PKD  

Since autosomal recessive PKD is typically discovered via ultrasound during the pregnancy period, patients with this type are often diagnosed in the womb.  

Signs of autosomal recessive PKD typically include: 

• Hypertension 

• Impaired renal function 

Patients may also have hepatic fibrosis that can lead to portal hypertension [11]. There are three varying severities and presentations of autosomal recessive PKD, which include: 

• Perinatal: little amniotic fluid and incomplete development of the lungs; most common and most severe 

• Neonatal and Infantile: minimal hepatic fibrosis, which is moderately severe 

• Juvenile: hepatic fibrosis and portal hypertension; less severe [11] 

Complications 

Both types of PKD can lead to a variety of complications, including kidney failure. As mentioned, some common complications of the dominant type are ruptured cysts, kidney stones, and urinary tract infections. Extrarenal complications are liver cysts, and a more serious complication is a ruptured intracranial aneurysm [5]. People with the dominant type are three to five times more likely to develop an intracranial aneurysm than the general population [4]. 

People with the recessive type may have growth failure and breathing problems, especially during the neonatal period. As both types of PKD can lead to kidney failure, patients may eventually need either hemodialysis or peritoneal dialysis. Some people need liver and kidney transplants, depending on the extent of organ failure [7].  

Polycystic Kidney Disease: Management 

This section discusses the diagnostic tests, treatment options, and nursing interventions in the care of patients with both types of polycystic kidney disease. 

Autosomal Dominant PKD 

Autosomal dominant PKD is diagnosed via renal ultrasound or computerized tomography (CT). Children or people with a strong family history of PKD may have genetic testing or renal ultrasounds completed even if they are asymptomatic [5]. The healthcare provider can diagnose a patient based on criteria, or the number of cysts found via ultrasound or CT results. Patients with the PKD1 are diagnosed via age group and number of cysts: 

• 15 to 29 years old: two or more cysts present on kidneys 

• 30 to 59 years old: two or more cysts present in each kidney 

• 60 years or older: two or more cysts present in each kidney [10]  

Criteria for diagnosing this type of PKD with the PKD2 gene mutation are less accurate. The healthcare provider will classify the severity of the patient’s kidney disease based on the Mayo classification system, lab values, and total kidney volume. If the patient has not been seen by a nephrologist, then the nurse can expect a referral for further treatment and evaluation [5].   

The patient will likely be on a variety of medications for treatment, including blood pressure medications, statins (for cholesterol), and others. The nurse should expect the patient to be on either an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB). ACE inhibitors are preferred over ARBSs. The patient’s blood pressure goal is less than 120 to 125/80 mm Hg if their GFR is reduced. However, if their GFR is normal, then their blood pressure goal is less than 110/75 mm Hg. If the patient’s blood pressure is not controlled initially by ACE inhibitors, then they may also be prescribed beta-blockers, calcium channel blockers, or thiazide diuretics [5].   

Another common medication the healthcare provider may prescribe is tolvaptan. Tolvaptan works by blocking vasopressin receptor signals and thus lowers the likelihood of cyst formation. The nurse should expect baseline and repeat liver function panels to be completed every four weeks to three months since tolvaptan can potentially cause liver failure [5]. Additionally, statins are prescribed – as dyslipidemia is common in patients with CKD – and can help slow progression [13]. Other potential medications for treatment are mammalian target of rapamycin (mTOR) inhibitors and somatostatin and somatostatin analogs, but these have not been clinically proven to be effective [5]. 

The nurse should encourage dietary modifications, such as limiting sodium intake to 2 grams per day and increasing water intake to at least three liters per day. Drinking three liters of water helps to suppress the antidiuretic hormone, vasopressin, which can lead to cyst formation [5]. 

Autosomal dominant PKD can lead to other kidney complications that require intervention. If the patient experiences flank pain, the nurse should notify the healthcare provider immediately. Flank pain can indicate an infection, stone, tumor, or other underlying renal complication is present. Renal cysts can rupture. The nurse encourages fluids and may administer intravenous (IV) fluids and pain medications, if necessary. If the patient has a urinary tract infection, the nurse administers IV or oral antibiotics, such as trimethoprim-sulfamethoxazole or fluoroquinolone. Kidney stones are often treated with potassium citrate. Sometimes, patients will need a nephrectomy or those with end-stage renal disease will need a kidney transplant, hemodialysis, or peritoneal dialysis [5]. 

Autosomal Recessive PKD 

Autosomal recessive PKD is typically diagnosed via ultrasound during the perinatal or neonatal period and warrants genetic testing. In the ultrasound, it will be difficult to tell the difference between the cortex and medulla of the kidneys. The neonate’s lungs will be underdeveloped and shortly after birth, they usually develop dilated intrahepatic biliary ducts. Autosomal recessive PKD oftentimes leads to neonatal mortality. However, some patients with this type will survive their first week after birth and will have kidney cysts along with liver enlargement and fibrosis, and spleen enlargement [11]. 

Treatment of autosomal recessive PKD is similar to that of the dominant type and depends on the severity of the patient’s symptoms. The nurse will monitor the patient’s respiratory status as some patients need ventilatory support. The nurse will also administer blood pressure medications as ordered, such as ACE inhibitors, to control the patient’s blood pressure. Most neonates also have growth failure, so the nurse will monitor the patient’s weight and growth. Additionally, the nurse will offer nutritional support and administer therapies, like iron or human growth hormone. The nurse will draw labs, such as renal and liver function panels, and notify the healthcare provider of any abnormal results [7]. Some patients require kidney and/or liver transplants depending on the extent of their condition. Ongoing treatments and medications are similar to those of the dominant type [11].

Patient and Family Education 

Nurses should educate patients and family members whenever possible about polycystic kidney disease and prevention strategies. The nurse and healthcare provider should advise patients about necessary dietary modifications, such as eating a low-sodium diet (under 2 grams per day) and increasing their water intake to three liters per day. Depending on the severity of kidney disease, patients may also need to start a low phosphorus, low potassium, and low protein diet [7].   

Education must also focus on smoking cessation and limiting alcohol consumption, as these can worsen the progression of PKD. Additionally, patients should be instructed on the importance of taking their medications, usage, and potential side effects. Instructions about avoiding use of non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen, should be reviewed. Potential complications of PKD should also be discussed with patients and their family members [5].

Conclusion

Both autosomal dominant and autosomal recessive polycystic kidney disease are types of chronic kidney disease and can lead to serious health complications. Therefore, nurses and healthcare providers must recognize the signs and symptoms and understand treatment for each. Managing the patient’s blood pressure, monitoring disease progression, and identifying and treating complications are key. Since PKD is a complicated disease, nurses and healthcare providers should educate patients and family members on the disease, dietary modifications, and medications.

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