NCLEX: Renal and urologic disorders

Renal and urologic disorders: A look at renal and urologic disorders

Focus topic: Renal and urologic disorders

The renal and urinary systems retain useful materials and excrete foreign or excessive materials and wastes. Through these basic functions, they profoundly affect other body systems and the patient’s overall health. Renal and urologic disorders can affect fluid and electrolyte balance and other important body functions.

 

 

Renal and urologic disorders: Anatomy and physiology

Focus topic: Renal and urologic disorders

The renal system consists of two kidneys, two ureters, one bladder, and one urethra. Working together, these structures remove wastes from the body, regulate acid-base balance by retaining or excreting hydrogen ions, and regulate fluid and electrolyte balance.

Renal and urologic disorders: The kidneys

Focus topic: Renal and urologic disorders

The kidneys are bean-shaped and highly vascular. Located retroperitoneally on either side of the vertebral column, they lie between the 12th thoracic and 3rd lumbar vertebrae. Abdominal contents, muscles attached to the vertebral column, and a perirenal fat layer protect them. The kidneys consist of the renal cortex, central renal medulla, internal calyces, and renal pelvis as well as the nephron, which serves as the kidney’s functional unit.

Renal and urologic disorders

Down and out

Focus topic: Renal and urologic disorders

The structures of the renal system, extending downward from the kidneys, include:

• ureters — tubes that act as ducts channeling urine to the bladder via peristaltic waves that occur about one to five times per minute; they measure about 10 to 12 (25.5 to 30.5 cm) in adults and have a diameter varying from 2 to 8 mm, with the narrowest portion being at the ureteropelvic junction
• urinary bladder — a hollow, spherical, muscular organ in the pelvis that serves to store urine delivered by the ureters; bladder capacity ranges from 500 to 600 ml in a normal adult (less in children and elderly people)
• urethra — a small duct that channels urine outside the body from the bladder; it has an exterior opening known as the urinary (urethral) meatus; in the female, the urethra ranges from 1 to 2 (2.5 to 5 cm) long, with the urethral meatus located anterior to the vaginal opening; in the male, the urethra is about 8 (20 cm) long, with the urethral meatus located at the end of the glans penis; the male urethra serves as a passageway for semen as well as urine.

Urine formation
The kidneys collect and eliminate wastes from the body in a threestep process:

In glomerular filtration, the kidney’s blood vessels, or glomeruli, filter the blood that flows through them. (See Understanding GFR, page 575.)

During tubular reabsorption, the minute canals (tubules) that make up the kidney reabsorb filtered fluid.

In tubular secretion, the tubules release the filtered substance.

Results may vary

Focus topic: Renal and urologic disorders

Varying with fluid intake and climate, total daily urine output averages 720 to 2,400 ml. For example, after a patient drinks a large volume of fluid, urine output increases as the body rapidly excretes excess water. If a patient restricts water intake or has an excessive intake of such solutes as sodium, urine output declines as the body retains water to maintain normal fluid concentration.

Renal and urologic disorders

Renal and urologic disorders

Hormones and the kidneys
Two hormones help regulate tubular reabsorption and secretion:

Antidiuretic hormone (ADH), which is produced by the pituitary gland, acts in the distal tubule and collecting ducts to increase water reabsorption and urine concentration. ADH deficiency decreases water reabsorption, causing dilute urine.

Aldosterone, which is produced by the adrenal gland, affects tubular reabsorption by regulating sodium retention and helping control potassium secretion by tubular epithelial cells. Other hormonal functions of the kidneys include:
• secretion of the hormone erythropoietin. In response to low arterial oxygen tension, the kidneys produce erythropoietin, which travels to the bone marrow and stimulates red blood cell (RBC) production.
• regulation of calcium and phosphorus balance. To help regulate calcium and phosphorus balance, the kidneys filter and reabsorb about one-half of unbound serum calcium and activate vitamin D3, a compound that promotes intestinal calcium absorption and regulates phosphate excretion.

Renin’s role

Focus topic: Renal and urologic disorders

The kidneys help regulate blood pressure by producing and secreting the enzyme renin in response to an actual or perceived decline in extracellular fluid volume. Renin, in turn, forms angiotensin I, which is converted to the more potent angiotensin II.

Potassium regulation
The distal tubules of the kidneys regulate potassium excretion. Responding to an elevated serum potassium level, the adrenal cortex increases aldosterone secretion. Aldosterone regulates potassium secretion into distal tubules so it can be eliminated from the body. If the body fails to produce enough aldosterone, potassium is reabsorbed and serum potassium levels increase.

Renal and urologic disorders: Assessment

Focus topic: Renal and urologic disorders

Assessing the urinary system may uncover clues to problems in any body system.

Renal and urologic disorders; History

Focus topic: Renal and urologic disorders

Begin your assessment with a thorough history, including current
and past health, family history, and lifestyle patterns.

Current health status
To determine the patient’s chief complaint, ask “What made you seek medical help?” Document the reason for seeking care in the patient’s own words. When a patient has a renal disorder, expect these common complaints:
• urinary frequency and urgency
• pain on urination
• difficulty urinating
• flank pain.

Previous health status
Explore all of the patient’s previous major illnesses, recurrent minor illnesses, accidents or injuries, surgical procedures, and allergies. Ask about a history of urologic-related disorders such as hyper tension.
Other questions to ask include:
• Have you ever had a urinary infection?
• Are you taking herbal medications or prescription, over-thecounter, or recreational drugs?
• Do you have pain or burning on urination?
• Is initiating urination difficult?
• What color is your urine?

• Are you allergic to drugs, foods, or other products? If yes, describe the reaction you experienced.
• Have you ever had a sexually transmitted disease (STD)?

Family history
For clues to risk factors, ask if blood relatives have ever been treated for renal or cardiovascular disorders, diabetes, cancer, or other chronic illness.

Lifestyle patterns
Investigate psychosocial factors that may affect the way the patient deals with his condition. Marital problems, unstable living conditions, job insecurity, and other stresses can strongly affect how he feels.

Self-reflection

Focus topic: Renal and urologic disorders

Also, find out how the patient views himself. Try to determine what concerns he has about his condition. For example, does he fear that the disease or therapy, such as hemodialysis, will affect his quality of life? If he can express his fears and concerns, you can develop appropriate nursing interventions more easily.

Renal and urologic disorders: Physical examination

Focus topic: Renal and urologic disorders

Begin the physical examination by documenting baseline vital signs and weighing the patient. Ask the patient to urinate into a specimen cup. Assess the specimen for color, odor, and clarity. Because the renal system affects many body functions, a thorough assessment includes examination of multiple related body systems using inspection, auscultation, percussion, and palpation techniques.

Inspection
Renal system inspection includes examination of the abdomen and urethral meatus.

Abdomen
Help the patient assume a supine position with his arms relaxed at his sides. Expose the patient’s abdomen from the xiphoid process to the symphysis pubis, and inspect the abdomen for gross enlargements or fullness by comparing the left and right sides,noting asymmetrical areas. In a normal adult, the abdomen is smooth, flat or scaphoid (concave), and symmetrical. Ask about scars, lesions, bruises, or discolorations found on abdominal skin.

Urethral meatus
Help the patient feel more at ease during your inspection by examining the urethral meatus last and by explaining beforehand how you’ll assess this area. Be sure to wear gloves.

Auscultation
Auscultate the renal arteries in the left and right upper abdominal quadrants by pressing the stethoscope bell lightly against the abdomen and instructing the patient to exhale deeply. Begin auscultating at the midline and work to the left. Then return to the midline and work to the right. Systolic bruits (whooshing sounds) or other unusual sounds are potentially significant abnormalities.

Percussion

After auscultating the renal arteries, percuss the patient’s kidneys to detect any tenderness or pain and percuss the bladder to evaluate its position and contents. (See Percussing the urinary organs.)

Palpation
Palpation of the kidneys and bladder is next. Through palpation, you can detect any lumps, masses, or tenderness. To achieve optimal results, ask the patient to relax his abdomen by taking deep breaths through his mouth.

Renal and urologic disorders: Diagnostic tests

Focus topic: Renal and urologic disorders

Advanced technology — including improved computer processing and imaging techniques — allows noninvasive assessment of renal and urologic problems that were previously detectable only by invasive techniques. These diagnostic tests can help evaluate the patient’s renal and urologic status.

Renal and urologic disorders: Blood studies

Focus topic: Renal and urologic disorders

When considered with urinalysis findings, blood studies help the doctor diagnose genitourinary disease and evaluate kidney function. Blood studies include blood urea nitrogen (BUN) and serum creatinine.

Renal and urologic disorders

BUN
Urea, the chief end product of protein metabolism, constitutes 40% to 50% of the blood’s nonprotein nitrogen. It’s formed from ammonia in the liver, filtered by the glomeruli, reabsorbed (to a limited degree) in the tubules, and finally excreted. Insufficient urea excretion elevates the BUN level.
Normal BUN levels range from 7 to 20 mg/dl for adults. For the most accurate interpretation of test results, examine BUN levels in conjunction with serum creatinine levels and in light of the patient’s underlying condition.

Nursing considerations
• Tell the patient that the test requires a blood sample.
• Check the patient’s medication history for drugs that may influence
BUN levels. (Chloramphenicol may depress levels; aminoglycosides and amphotericin B can elevate levels.)

• If a hematoma develops at the venipuncture site, apply warm soaks.

Renal and urologic disorders

Serum creatinine
Creatinine, another nitrogenous waste, results from muscle metabolism of creatine. Normal serum creatinine values for adult males range from 0.6 to 1.2 mg/dl; for adult females, 0.4 to 1 mg/dl. Diet and fluid intake don’t affect serum creatinine levels, but muscle mass does.
This test measures renal damage more reliably than BUN level measurements because severe, persistent renal impairment is virtually the only reason that creatinine levels rise significantly. Creatinine levels greater than 1.5 mg/dl indicate 66% or greater loss of renal function; levels greater than 2 mg/dl indicate renal insufficiency.

Nursing considerations
• Tell the patient that the test requires a blood sample.
• Check the patient’s medication history for drugs that may influence serum creatinine levels (ascorbic acid, barbiturates, and diuretics may raise serum creatinine levels).
• If a hematoma develops at the venipuncture site, apply warm soaks.

Renal and urologic disorders: Clearance tests

Focus topic: Renal and urologic disorders

Clearance tests for filtration, reabsorption, and secretion permit a precise evaluation of renal function. These tests measure the volume of plasma that can be cleared of a substance (such as creatinine) per unit of time, thus helping evaluate urine-formingmechanisms. They also measure renal blood flow, which renal disease may reduce.

Creatinine clearance
The creatinine clearance test, commonly used to assess glomerular filtration rate (GFR), determines how efficiently the kidneys clear creatinine from the blood. Normal values depend on the patient’s age.

Nursing considerations
• Tell the patient the test requires a timed urine specimen and at least one blood sample.

• A high-protein diet before the test and strenuous physical exerciseduring the collection period may increase creatinine excretion. Inform the patient that he shouldn’t eat an excessive amount of meat before the test and should avoid strenuous physical exercise during the collection period.

Urea clearance
The urea clearance test measures urine levels of urea, the chief end product of protein metabolism and the chief nitrogenous component of urine. The urea clearance rate usually ranges from 64 to 100 ml/minute at a urine flow rate of 2 ml/minute or more. At flow rates of less than 2 ml/minute, the normal range decreases to 40 to 70 ml/minute.

Nursing considerations
• Tell the patient that the test requires two timed urine specimens and one blood sample.
• Instruct him to fast after midnight before the test and to abstain from exercise before and during the test.

Renal and urologic disorders: Radiologic and imaging studies

Focus topic: Renal and urologic disorders

Radiologic and imaging studies help screen for renal and urologic abnormalities. These studies include computed tomography (CT) scan, excretory urography, kidney-ureter-bladder (KUB) radiography, magnetic resonance imaging (MRI), radionuclide renal scans, renal angiography, ultrasonography, and voiding cystourethrography.

CT scan
In a renal CT scan, the image’s density reflects the amount of
radiation absorbed by renal tissue, thus permitting identification
of masses and other lesions.

Nursing considerations
• If contrast enhancement isn’t scheduled, inform the patient that he need not restrict food or fluids. If a contrast medium will be used, instruct him to fast for 4 hours before the test.
• If contrast enhancement is ordered, check the patient’s history for an allergy to iodine, shellfish, or previous contrast media.
• Inform the patient that he’ll be positioned on an X-ray table and that a scanner will take films of his kidneys. Warn him that he may hear loud, clacking sounds as the scanner rotates around his body.

• Just before the procedure, instruct the patient to put on a hospital gown and to remove any metallic objects that could interfere with the scan.

Excretory urography
After I.V. administration of a contrast medium, this common procedure (also known as I.V. pyelography) allows visualization of the renal parenchyma, calyces, pelvises, ureters, bladder and, in some cases, the urethra.

Picture perfect

Focus topic: Renal and urologic disorders

In the 1st minute after injection (the nephrographic stage), the contrast medium delineates the size and shape of the kidneys. After 3 to 5 minutes (the pyelographic stage), the contrast medium moves into the calyces and pelvises, allowing visualization of cysts, tumors, and other obstructions.

Nursing considerations
• Check the patient’s history for hypersensitivity to iodine, iodinecontaining foods, or contrast media containing iodine.
• Check the patient’s laboratory results for elevated BUN and creatinine levels. Excretory urography is contraindicated in patients with renal insufficiency.
• Ensure that the patient is well hydrated, and instruct him to fast for 8 hours before the test.
• Inform the patient that he may experience a transient burning sensation and metallic taste when the contrast medium is injected.

KUB radiography
KUB radiography is the main radiologic study used for the urinary system. The KUB study, consisting of plain, contrast-free X-rays, shows kidney size, position, and structure as well as calculi and other lesions. Before performing a renal biopsy, the doctor may use this test to determine kidney placement. For diagnostic purposes, however, the KUB study provides limited information.

Nursing considerations
• Inform the patient that he need not restrict food or fluids before the test.
• No specific posttest care is necessary.

MRI
MRI provides tomographic images that reflect the differing hydrogen densities of body tissues. Physical, chemical, and cellular microenvironments modify these densities, as do the fluid characteristics of tissues. MRI can provide precise images of anatomic detail and important biochemical information about the tissue examined and can efficiently visualize and stage kidney, bladder, and prostate tumors.

Nursing considerations
• Before the patient enters the MRI chamber, make sure he has removed all metal objects, such as earrings, watch, necklace, bracelets, and rings. Patients with internal metal objects, such as pacemakers or aneurysm clips, can’t undergo MRI testing.
• If you’re accompanying the patient, be sure to remove metal objects from your pockets, such as scissors, forceps, a penlight, metal pens, and your credit cards (the magnetic field will erase the numerical information in the code strips).
• Tell the patient that he must remain still throughout the test, which takes about 45 minutes. If the patient complains of claustrophobia, reassure him and provide emotional support.

Radionuclide renal scan
A radionuclide renal scan, which may be substituted for excretory urography in patients who are hypersensitive to contrast media, involves I.V. injection of a radionuclide, followed by scintiphotography. Observation of the uptake concentration and radionuclide transit during the procedure allows assessment of renal blood flow, nephron and collecting system function, and renal structure.

Nursing considerations
• Inform the patient that he’ll receive an injection of a radionuclide and may experience transient flushing and nausea. Emphasize that he’ll receive only a small amount of radionuclide, which is usually excreted within 24 hours.
• After the test, instruct the patient to flush the toilet immediately every time he urinates for 24 hours as a radiation precaution.

Renal angiography
Renal angiography permits radiographic examination of the renal vasculature and parenchyma after arterial injection of a contrast medium. Renal venography (angiography of the veins) may be performed to detect renal vein thrombosis and venous extension of renal cell carcinoma.

Nursing considerations
• Check the patient’s history for hypersensitivity to iodine-based contrast media or iodine-containing foods such as shellfish.

• Instruct him to fast for 8 hours before the test and drink extra fluids the day before and after the test to maintain adequate hydration (or start an I.V. line if needed).
• Keep the patient flat in bed after the procedure; keep the leg on the affected side straight for at least 6 hours or as ordered.

Ultrasonography
Ultrasonography uses high-frequency sound waves to reveal internal structures. The pulse-echo transmission technique of this test determines the kidney’s size, shape, and position. It also reveals internal structures and perirenal tissue and helps the practitioner diagnose complications after kidney transplantation. Doppler ultrasonography allows the evaluation of the speed, direction, and patterns of blood flow.

Nursing considerations
• Tell the patient that he’ll either be prone or supine during the test.
• Explain that a technician will apply a water-based conductive gel on the patient’s skin and then press a probe or transducer against the skin and move it across the area being tested.

Voiding cystourethrography
In voiding cystourethrography, a urinary catheter inserted into the bladder allows instillation of a contrast medium by gentle syringe pressure or gravity. Fluoroscopic films or overhead radiographs demonstrate bladder filling and then show excretion of the contrast medium as the patient voids.

Nursing considerations
• Check the patient’s history for hypersensitivity to contrast media or iodine-containing foods such as shellfish.
• Inform the patient that a catheter will be inserted into his bladder and a contrast medium will be instilled through the catheter. Tell him he may experience a feeling of fullness and an urge to void when the contrast is instilled.
• After the test, instruct the patient to drink lots of fluids to reduce burning on urination and to flush out any residual contrast dye.
• Monitor for chills and fever related to extravasation of contrast material or urinary sepsis.

FURTHER READING/STUDY:

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