The kidneys participate in urinary elimination by filtering wastes and balancing fluids, electrolytes, acids, and bases. Any problem that disrupts kidney function limits the ability to meet that need and has the potential to impair general homeostasis (Fig. 70-1). The kidneys work together with many other organ systems. Thus kidney disorders affect systemic health and can lead to life-threatening outcomes. Kidney disorders are classified as congenital, obstructive, infectious, glomerular, and degenerative. Kidney tumors and kidney trauma are also described in this chapter. Acute kidney injury and chronic kidney disease are discussed in Chapter 71.

FIG. 70-1 Unbalanced body water, electrolytes, and waste products as a result of kidney problems that prevent adjustments in urinary elimination.

Congenital Disorders

Polycystic Kidney Disease

Pathophysiology

Polycystic kidney disease (PKD) is an inherited disorder in which fluid-filled cysts develop in the nephrons. In the dominant form, only a few nephrons have cysts until the person reaches his or her 30s. In the recessive form of the disease, nearly 100% of nephrons have cysts from birth. Cysts develop anywhere in the nephron as a result of abnormal kidney cell division.

Over time, small cysts become much larger (up to a few centimeters in diameter) and more widely distributed. The growing cysts damage the glomerular and tubular membranes. As the cysts fill with fluid and enlarge, the nephron and kidney function become less effective.

The kidney tissue is eventually replaced by nonfunctioning cysts, which look like clusters of grapes (Fig. 70-2). The kidneys become very large. Each cystic kidney may enlarge to two or three times its normal size, becoming as large as a football, and may weigh 10 pounds or more each. Other abdominal organs are displaced, and the patient has pain. The fluid-filled cysts are also at increased risk for infection, rupture, and bleeding, which increase pain.

FIG. 70-2 External surface **(A)** and internal surface **(B)** of a polycystic kidney.

Most patients with PKD have high blood pressure. The cause of hypertension is related to kidney ischemia from the enlarging cysts. As the vessels are compressed and blood flow to the kidneys decreases, the renin-angiotensin system is activated, raising blood pressure. Control of hypertension is a top priority because proper treatment can disrupt the process that leads to further kidney damage.

Cysts may occur also in other tissues, such as the liver and blood vessels. They may reduce liver function. In addition, the incidence of cerebral aneurysms (outpouching and thinning of an artery wall) is higher in patients with PKD. These aneurysms may rupture, causing bleeding and sudden death. For reasons as yet unknown, kidney stones occur in 8% to 36% of the patients with PKD. Heart valve problems (e.g., mitral valve prolapse), left ventricular hypertrophy, and colonic diverticula also are common in patients with PKD.

Etiology and Genetic Risk

PKD has several forms and can be inherited as either an autosomal dominant trait or, less commonly, as an autosomal recessive trait. People who inherit the recessive form of PKD usually die in early childhood. The 5% to 10% incidence of PKD in patients with no family history occurs as a result of a new gene mutation.

Genetic/Genomic Considerations

The autosomal dominant form of PKD (ADPKD) is the most common form of polycystic disease. Children of parents who have the autosomal dominant form of PKD have a 50% chance of inheriting the gene that causes the disease. Fig. 70-3 shows a typical pedigree for a family with ADPKD. Presentation of ADPKD can vary for age of onset, manifestations, and illness severity, even within one family. However, it is highly penetrant, meaning that nearly 100% of people who inherit a PKD gene will develop kidney cysts by age 30 (Nussbaum et al., 2007). Half of these people develop chronic kidney disease by age 50 years. ADPKD-1 is the most common and most severe form of the autosomal dominant disease. ADPKD-2 has a slower rate of cyst formation, so symptoms occur later in life and progression to end-stage kidney disease and other complications is delayed.

FIG. 70-3 Four-generation pedigree for autosomal dominant polycystic kidney disease (ADPKD). Colored-in symbols indicate family members with ADPKD. Slashes indicate the person has died.

Autosomal recessive PKD is rare, and most people with the disease die in early childhood. It is caused by a gene mutation different from the dominant form. To inherit a recessive gene, both parents must carry a copy of the mutated allele and both mutated alleles must be inherited. Thus each child has a 1-in-4 chance of inheriting autosomal recessive polycystic disease.

There is no way to prevent PKD, although early detection and management of hypertension may slow the progression of kidney damage. Genetic counseling may be useful for adults who have one parent or both parents with PKD. Family history analysis is a simple assessment that can be used to help identify people at risk for PKD (see Fig. 70-3).

Incidence/Prevalence

PKD is a common disorder, affecting 250,000 to 500,000 people in the United States. It is more common in white people than in people of other races. Men and women have an equal chance of inheriting the disease because the gene responsible for PKD is not located on the sex chromosomes (Polycystic Kidney Disease Foundation, 2011).

Patient-Centered Collaborative Care

Assessment

History

Explore the family history of a patient with suspected or actual PKD, and ask whether either parent was known to have PKD or whether there is any family history of kidney disease. The age at which the problem was diagnosed in the parent and any related complications are important to obtain. Ask about constipation, abdominal discomfort, a change in urine color or frequency, high blood pressure, headaches, and a family history of sudden death from a stroke.

Physical Assessment/Clinical Manifestations

Chart 70-1 lists key features of PKD. Pain is often the first manifestation. Inspect the abdomen. A distended abdomen is common as the cystic kidneys swell and push the abdominal contents forward. Polycystic kidneys are easily palpated because of their increased size. Proceed with gentle abdominal palpation because the cystic kidneys and nearby tissues may be tender and palpation is uncomfortable.

Chart 70-1

Key Features

Polycystic Kidney Disease

• Abdominal or flank pain

• Hypertension

• Nocturia

• Increased abdominal girth

• Constipation

• Bloody or cloudy urine

• Kidney stones

The patient also may have flank pain as a dull ache or as sharp and intermittent discomfort. Dull, aching pain is caused by increased kidney size with distention or by infection within the cyst. Sharp, intermittent pain occurs when a cyst ruptures or a stone is present. When a cyst ruptures, the patient may have bright red or cola-colored urine. Infection is suspected if the urine is cloudy or foul smelling or if there is dysuria (pain on urination).

Nocturia (the need to urinate excessively at night) is an early manifestation and occurs because of decreased urine concentrating ability. As kidney function further declines, the patient has increasing hypertension, edema, and uremic manifestations such as anorexia, nausea, vomiting, pruritus, and fatigue (see Chapter 71). Because berry aneurysms often occur in patients with PKD, a severe headache with or without neurologic or vision changes requires attention.

Psychosocial Assessment

As an inherited disorder, PKD may cause psychosocial responses. The patient often has seen the effects and problems of the disease in close family members. He or she may have had a parent who died or close relatives who required dialysis or transplantation. While obtaining the family history, listen carefully for spoken and unspoken feelings of anger, resentment, futility, sadness, or anxiety. Such feelings may need further exploration. The focus of the feelings may be one or both parents or the process of diagnosis and treatment. Feelings of guilt and concern for the patient’s children may also complicate the issue.

Diagnostic Assessment

Urinalysis shows proteinuria (protein in the urine) once the glomeruli are involved. Hematuria (blood in the urine) may be gross or microscopic. Bacteria in the urine indicate infection, usually in the cysts. Obtain a urine sample for culture and sensitivity testing when there is evidence of infection. As kidney function declines, serum creatinine and blood urea nitrogen (BUN) levels rise. With decreasing kidney function, creatinine clearance decreases. Changes in kidney handling of sodium may cause either sodium losses or sodium retention.

Diagnostic studies include renal sonography, computed tomography (CT), and magnetic resonance imaging (MRI). Small cysts are detected by sonography, CT, or MRI. Renal sonography shows evidence of PKD, with minimal risk.

Decision-Making Challenge

Patient-Centered Care; Teamwork and Collaboration

The 36-year-old unaffected daughter of a 63-year-old man with PKD is visiting her two 31-year-old sisters (identical twins) who are both hospitalized with acute complications of their PKD (see Fig. 70-3). You find the unaffected sister in the hallway crying. She tells you that she feels sad that her sisters are suffering so much and guilty that she has escaped the disease. She also tells you that, although she wants to donate a kidney to the sister whose disease has already progressed to end-stage kidney disease (ESKD), she is not a blood type match. (Both parents have type A blood, the unaffected sister has type A blood, and the affected twin sisters have type O blood.) In addition, she has a 2-year-old son and a 6-week-old son, and she fears that they may either develop the disease or pass it on to their children. She also tells you that she is grateful that her father’s PKD is not as severe as her sisters’ disease.

1 What is the pattern of inheritance for the PKD depicted in Fig. 70-3 (and explain why it could not be another pattern of inheritance)?

2 Are the unaffected sister’s fears of passing the disease on to her children or grandchildren founded or unfounded? Provide a rationale for your decision.

3 Is the unaffected sister correct in thinking that her blood type difference eliminates the possibility that she could donate a kidney to one of her sisters? Why or why not? (You may need to review blood type issues in Chapter 42 and kidney transplantation issues in Chapter 71.)

4 What comments or suggestions could you make to help the unaffected sister feel less guilty about her own good health?

Interventions

Interventions for the patient with PKD include pain management and prevention of infection, constipation, hypertension, and chronic kidney disease. When the disease progresses to the point that the kidneys no longer function to clear wastes, care becomes similar to that needed for the patient with end-stage kidney disease (see Chapter 71).

Managing Pain

Comfort strategies include drug therapy and complementary approaches. A combination may be most effective. NSAIDs are used cautiously because of their tendency to reduce kidney blood flow. Aspirin-containing compounds are avoided to reduce the risk for bleeding.

If cyst infection causes discomfort, antibiotics such as trimethoprim/sulfamethoxazole (Bactrim, Septra, Trimpex) or ciprofloxacin (Cipro) are prescribed. (See Chart 69-4 in Chapter 69.) These drugs enter the cyst wall. Monitor the serum creatinine levels because antibiotic therapy can be nephrotoxic. Apply dry heat to the abdomen or flank to promote comfort when kidney cysts are infected. When pain is severe, cysts can be reduced by needle aspiration and drainage; however, they usually refill.

Teach the patient methods of relaxation and comfort using deep breathing, guided imagery, or other strategies. The expected outcome is patient self-management. (See Chapter 5 for pain management.)

Preventing Constipation

Teach the patient who has adequate urine output how to prevent constipation by maintaining adequate fluid intake, increasing dietary fiber when fluid intake is more than 2500 mL/24 hr, and exercising regularly. Explain that pressure on the large intestine may occur as the polycystic kidneys increase in size. The patient should know that these recommendations for bowel management might change, particularly if end-stage kidney disease also develops. Advise him or her about the use of stool softeners and bulk agents, including the careful use of laxatives, to prevent chronic constipation.

Controlling Hypertension and Preventing End-Stage Kidney Disease

Blood pressure control is necessary to reduce cardiovascular complications and slow the progression of kidney dysfunction. Nursing interventions include education to promote self-management and understanding. When kidney impairment results in decreased urine concentration with nocturia and low urine specific gravity, urge the patient to drink at least 2 L of fluid per day to prevent dehydration, which can further reduce kidney function. Restricting sodium intake may help control blood pressure. See Chapter 38 for a detailed discussion about the causes and management of hypertension.

Drug therapy for blood pressure control includes antihypertensive agents and diuretics. Antihypertensive agents include angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers, beta blockers, and vasodilators (see Chapter 38). ACE inhibitors may help control the cell growth aspects of PKD and reduce microalbuminuria.

Teach the patient and family how to measure and record blood pressure. Help the patient establish a schedule for self-administering drugs, monitoring daily weights, and keeping blood pressure records (Chart 70-2). Explain the potential side effects of the drugs. Make available written materials, such as drug teaching cards and booklets.

Chart 70-2

Patient And Family Education: Preparing for Self-Management

Polycystic Kidney Disease

• Measure and record your blood pressure daily, and notify your health care provider for consistent changes in blood pressure.

• Take your temperature if you suspect you have a fever.

• Weigh yourself every day at the same time of day and with the same amount of clothing; notify your physician or nurse if you have a sudden weight gain.

• Limit your intake of salt to help control your blood pressure.

• Notify your physician or nurse if your urine smells foul or has blood in it.

• Notify your physician or nurse if you have a headache that does not go away or if you have visual disturbances.

• Monitor bowel movements to prevent constipation.

A low-sodium diet is often prescribed to control the hypertension that usually occurs with PKD. However, some patients may have salt wasting and should not follow a sodium-restricted diet. As the disease progresses, the protein intake may be limited to slow the development of end-stage kidney disease. Assist the patient and family in understanding the diet plan and why it was prescribed. Work closely with the dietitian to foster the patient’s understanding. Also refer the patient for nutritional counseling.

Health Care Resources

The Polycystic Kidney Disease Foundation (www.pkdcure.org) and the National Kidney & Urologic Diseases Information Clearinghouse (NKUDIC) of the National Institute of Diabetes and Digestive and Kidney Diseases (www2.niddk.nih.gov) conduct research and provide education about PKD. Many pamphlets are available; there is a fee for some materials. Chapters of the National Kidney Foundation (NKF) and the American Association of Kidney Patients (AAKP) also have resources for information and support.

Obstructive Disorders