UNDERSTANDING MEDICAL-SURGICAL NURSING_1 potx

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Unit Unit N N INE INE Underst Underst anding anding the Renal and the Renal and Ur Ur inar inar y S y S ystem ystem Williams_ch34_571-587 12/6/02 2:59 PM Page 571 Copyright © 2003 F.A. Davis Company Williams_ch34_571-587 12/6/02 2:59 PM Page 572 Copyright © 2003 F.A. Davis Company 34 34 Ur Ur inar inar y S y S ystem Function, ystem Function, Assessment Assessment , and , and T T herap herap eutic Measur eutic Measur es es Betty J. Ackley KEY TERMS cystoscopy (sis-TAHS-koh-pee) dysuria (dis-YOO-ree-ah) hematuria (HEM-uh-TYOOR-ee-ah) percutaneous (PER-kyoo-TAY-nee-us) pyelogram (PIE-loh-GRAM) uremia (yoo-REE-mee-ah) QUESTIONS TO GUIDE YOUR READING 1. What is the normal anatomy of the urinary system? 2. What is the normal function of the urinary system? 3. What are the effects of aging on the urinary system? 4. What is normal and oliguric 24-hour urinary output? 5. What data should you collect when caring for a patient with a disorder of the urinary system? 6. How do you collect a midstream, clean-catch urine specimen and 24- hour creatinine clearance specimen? 7. What is the meaning of an elevated serum creatinine, blood urea nitrogen, and uric acid level? 8. What is the preparation and aftercare for diagnostic tests of the urinary system? 9. Which nursing actions can be taken to decrease the risk of infection in catheterized patients? 10. What nursing care should be given to patients who are incontinent? 573 The process of urine formation thus helps maintain the normal composition, volume, and pH of blood and tissue fluid. Kidneys The two kidneys are located in the upper abdominal cavity behind the peritoneum on each side of the vertebral col- umn. The upper portions of both kidneys rest on the lower surface of the diaphragm and are enclosed and protected by the lower ribcage. The kidneys are cushioned by surrounding adipose tissue, which is in turn covered by a fibrous con- nective membrane called the renal fascia; both help hold the kidneys in place. On the medial side of each kidney is an indentation called the hilus, where the renal artery enters and the renal vein and ureter emerge. The renal artery is a branch of the abdominal aorta, and the renal vein re- turns blood to the inferior vena cava. The ureter carries urine from the kidney to the urinary bladder. REVIEW OF ANATOMY AND PHYSIOLOGY The urinary system consists of two kidneys, two ureters, the urinary bladder, and the urethra. The kidneys form urine, and the rest of the system eliminates urine. The purpose of urine formation is the removal of potentially toxic waste products from the blood; however, the kidneys have other equally important functions as well: ■ Regulation of the blood volume by the excretion or conservation of water ■ Regulation of the electrolyte balance of the blood by the excretion or conservation of minerals ■ Regulation of the acid-base balance of the blood by the excretion or conservation of ions such as hydrogen or bicarbonate ■ Regulation of all of the above in tissue fluid Williams_ch34_571-587 12/6/02 2:59 PM Page 573 Copyright © 2003 F.A. Davis Company 574 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM Internal Structure of the Kidney A frontal section of the kidney shows three distinct areas (Fig. 34–1). The outermost area is the renal cortex, which contains the parts of the nephrons called renal corpuscles and convoluted tubules. The middle area is the renal medulla, which contains loops of Henle and collecting tubules. The renal medulla consists of wedge-shaped pieces called renal pyramids; the apex, or papilla, of each pyramid points medially. The third area is a cavity called the renal pelvis; it is formed by the expansion of the ureter within the kidney at the hilus. Funnel-shaped extensions of the renal pelvis, called calyces, enclose the papillae of the renal pyramids. Urine flows from the pyramids into the calyces, then to the renal pelvis, and finally into the ureter. Nephron The nephron is the structural and functional unit of the kidney. Urine is formed in the approximately 1 million nephrons in each kidney. The two major parts of a nephron are the renal corpuscle and the renal tubule; these and their subdivisions and blood vessels are shown in Fig. 34–2. A renal corpuscle consists of a glomerulus surrounded by a Bowman’s capsule. The glomerulus is a capillary network that arises from an afferent arteriole and empties into an efferent arteriole. The diameter of the efferent arteriole is smaller than that of the afferent arteriole, which helps maintain a fairly high blood pressure in the glomerulus. Bowman’s capsule is the expanded end of a renal tubule; it encloses the glomerulus. The inner layer of Bowman’s capsule has pores and is highly permeable; the outer layer has no pores and is not permeable. The space between the inner and outer layers contains renal filtrate, the fluid that is formed from the blood in the glomerulus and that will even- tually become urine. The renal tubule continues from Bowman’s capsule and consists of the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule. The distal convoluted tubules from several nephrons empty into a collecting tubule. Several collecting tubules then unite to form a pap- illary duct that empties urine into a calyx of the renal pelvis. All the parts of the renal tubule are surrounded by the peritubular capillaries, which arise from the efferent arteriole and receive the materials reabsorbed by the renal tubules. Blood Vessels of the Kidney The pathway of blood flow through the kidney is an essen- tial part of the process of urine formation. Blood from the abdominal aorta enters the renal artery, which branches ex- tensively within the kidney into smaller arteries. The small- est arteries give rise to afferent arterioles in the renal cortex. From the afferent arterioles, blood flows into the glomeruli (capillaries), to efferent arterioles, to peritubular capillaries, to veins in the kidney, to the renal vein, and finally to the inferior vena cava. In this pathway are two sets of capillari- esthat is, two sites of exchanges between the blood and the surrounding tissues (in this case, the parts of the nephrons). The exchanges that take place in the capillaries of the kidneys form urine from blood plasma. Formation of Urine The formation of urine involves three major processes: glomerular filtration in the renal corpuscles, tubular reabsorption, and tubular secretion. Glomerular Filtration Filtration is the process by which blood pressure forces plasma and dissolved materials out of capillaries. In glomerular filtration, blood pressure forces plasma, dissolved substances, and small proteins out of the glomeruli and into Bowman’s capsules. This fluid is then called renal filtrate. The blood pressure in the glomeruli is relatively high, about 60 mm Hg. The pressure in Bowman’s capsule is low, and its inner layer is permeable, so that approximately 20 to 25 percent of the blood that enters glomeruli becomes renal filtrate in Bowman’s capsules. The larger proteins and blood cells are too large to be forced out of the glomeruli; they remain in the blood. Waste products such as urea and ammonia are dissolved in plasma, so they pass to the renal filtrate, as do dissolved nutrients and minerals. Renal filtrate is similar to blood plasma except that there is far less protein and no blood cells are present. The glomerular filtration rate (GFR) is the amount of renal filtrate formed by the kidneys in 1 minute; it averages 100 to 125 mL. The GFR may change if the rate of blood flow through the kidney changes. If blood flow increases, the GFR increases, more filtrate is formed, and urinary output increases. If blood flow decreases, the GFR decreases, less filtrate is formed, and urinary output decreases. Nephron Renal cortex Renal pelvis Renal medulla (pyramids) Papilla of pyramid Calyx Renal artery Renal vein Ureter Figure 34–1 Frontal section of the left kidney. (From Scan- lon,V, and Sanders,T: Essentials of Anatomy and Physiology, ed 3. FA Davis, Philadelphia, 1999, p 405, with permission.) Williams_ch34_571-587 12/6/02 2:59 PM Page 574 Copyright © 2003 F.A. Davis Company Chapter 34 URINARY SYSTEM FUNCTION, ASSESSMENT, AND THERAPEUTIC MEASURES 575 Tubular Reabsorption Tubular reabsorption is the recovery of useful materials from the renal filtrate and their return to the blood in the peritubular capillaries. Approximately 99 percent of the renal filtrate formed is reabsorbed, and normal urinary output is 1000 to 2000 mL per 24 hours. Most reabsorption takes place in the proximal convoluted tubules, whose cells have microvilli that greatly increase their surface area. The distal convoluted tubules and collecting tubules are also important sites for the reabsorption of water. The mechanisms of reabsorption are active transport, passive transport, osmosis, and pinocytosis. Active transport requires energy in the form of adeno- sine triphosphate (ATP); the cells of the renal tubule use energy to transport useful materials such as glucose, amino acids, vitamins, and positive ions back to the blood. For many of these substances there is a threshold level of Proximal convoluted tubule Glomerulus Bowman's capsule (inner layer) Bowman's capsule (outer layer) Distal convoluted tubule Renal cortex Renal medulla Efferent arteriole Juxtaglomerular cells Afferent arteriole Peritubular capillaries Loop of Henle Collecting tubule Figure 34–2 A nephron and its associated blood vessels. (From Scanlon,V, and Sanders,T: Essentials of Anatomy and Physiology, ed 3. FA Davis, Philadelphia, 1999, p 406, with permission.) Williams_ch34_571-587 12/6/02 3:00 PM Page 575 Copyright © 2003 F.A. Davis Company 576 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM reabsorption—that is, a limit to how much the renal tubules can remove from the filtrate. The level of a substance in the renal filtrate is directly related to its blood level. If the blood level of a substance such as glucose is normal, the filtrate level is normal, the threshold level cannot be exceeded, and no glucose appears in the urine. Passive transport is the mechanism by which negative ions are reabsorbed. They are returned to the blood after the reabsorption of positive ions, because unlike charges attract. The reabsorption of water is by osmosis following the reabsorption of minerals, especially sodium. The conservation of water is very important to maintain normal blood volume and blood pressure. The hormones that influence the reabsorption of water or minerals are summarized in Table 34–1. Small proteins in the filtrate are reabsorbed by pinocytosis; the proteins become adsorbed to the membranes of the tubule cells and are engulfed and digested. Normally, all proteins in the filtrate are reabsorbed and none are found in urine. Tubular Secretion In tubular secretion, substances are actively secreted from the blood in the peritubular capillaries into the filtrate in the renal tubules. Waste products, such as ammonia and creatinine, and the metabolic products of medications may be secreted into the filtrate to be eliminated in urine. Hy- drogen ions may be secreted by the tubule cells to help maintain the normal pH of the blood. In summary, tubular reabsorption conserves useful materials, tubular secretion may add unwanted substances to the filtrate, and most waste products simply remain in the filtrate and are excreted in urine. The Kidneys and Acid-Base Balance The kidneys are the organs most responsible for maintain- ing the normal pH range of blood and tissue fluid. They have the greatest ability to compensate for or correct the pH changes that are part of normal body metabolism or the result of disease. At its simplest, this function of the kidneys may be de- scribed as follows: If body fluids are becoming too acidic, the kidneys secrete more hydrogen ions into the renal filtrate and return more bicarbonate ions back to the blood. This helps raise the pH of the blood back to normal. In the op- posite situation, when the body fluids become too alkaline, the kidneys return hydrogen ions to the blood and excrete bicarbonate ions in urine. This helps lower the pH of the blood back to normal. Other Functions of the Kidneys Some functions of the kidneys are not related to the formation of urine. These include the secretion of renin, activa- tion of vitamin D, and production of erythropoietin. The production of renin influences urine formation and is considered first. When blood pressure decreases, the juxtaglomerular cells in the walls of the afferent arterioles secrete the enzyme renin. Renin then initiates the renin-angiotensin- aldosterone mechanism, which results in the formation of angiotensin II. (See Chapter 15.) Angiotensin II stimulates vasoconstriction and increases the secretion of aldosterone, both of which help raise blood pressure. Vitamin D exists in several structural forms, which are converted to calciferol, the most active form, by the kidneys. Vitamin D is important for the efficient absorption of calcium and phosphate from food in the small intestine. Erythropoietin is a hormone secreted by the kidneys during states of hypoxia; it stimulates the red bone marrow to increase the rate of red blood cell (RBC) production. With more RBCs in circulation, the oxygen-carrying capacity of the blood is greater and the hypoxic state may be corrected. Elimination of Urine The ureters, urinary bladder, and urethra do not change the composition or volume of urine but are responsible for its elimination. Ureters The ureters are behind the peritoneum of the dorsal abdominal cavity. Each ureter extends from the hilus of a kidney to the lower, posterior side of the urinary bladder. The smooth muscle in the wall of the ureter contracts in peri- staltic waves to propel urine toward the urinary bladder. As the bladder fills, it expands and compresses the lower ends of the ureters to prevent backflow of urine. Urinary Bladder The urinary bladder is a muscular sac below the peritoneum and behind the pubic bones. In women the bladder is infe- Hormone (Gland) Function Aldosterone (adrenal cortex) Antidiuretic hormone (posterior pituitary) Atrial Natriuretic hormone (atria of heart) Parathyroid hormone (parathyroid glands) Source: Scanlan, V, and Sanders, T: Essentials of Anatomy and Physiology, ed 3. FA Davis, Philadelphia, 1999, p 410, with permission. TABLE 34–1 Effects of Hormones on the Kidneys Promotes reabsorption of sodium ions from the filtrate to the blood and excretion of potassium ions into the filtrate. Water is reabsorbed following the reabsorption of sodium. Promotes reabsorption of water from the filtrate to the blood. Decreases reabsorption of sodium ions, which remain in the filtrate. More sodium and water are eliminated in the urine. Promotes reabsorption of calcium ions from the filtrate to the blood and excretion of phosphate ions into the filtrate. Williams_ch34_571-587 12/6/02 3:00 PM Page 576 Copyright © 2003 F.A. Davis Company Chapter 34 URINARY SYSTEM FUNCTION, ASSESSMENT, AND THERAPEUTIC MEASURES 577 rior to the uterus; in men the bladder is superior to the prostate gland. The functions of the bladder are the tempo- rary storage of urine and its elimination. Urethra The urethra carries urine from the bladder to the exterior. Within its wall is the external urethral sphincter, which is made of skeletal muscle and is under voluntary control. In women the urethra is 1 to 1.5 inches long and is an- terior to the vagina. In men the urethra is 7 to 8 inches long and extends through the prostate gland and penis. The male urethra carries semen, as well as urine. The Urination Reflex Urination is a spinal cord reflex over which voluntary control may be exerted. The stimulus is the stretching of the detrusor muscle as urine accumulates in the bladder. Sen- sory impulses travel to the sacral spinal cord, and motor impulses return along parasympathetic nerves to the detrusor muscle, causing contraction. At the same time, the internal urethral sphincter relaxes. If the external urethral sphincter is voluntarily relaxed, urine flows into the urethra and the bladder is emptied. Characteristics of Urine Amount Normal urinary output is 1000 to 2000 mL per 24 hours. Any changes in fluid intake or other fluid output (such as sweating) changes this volume. Color The color of urine is often referred to as straw or amber. Di- lute urine is a lighter color (straw) than is concentrated urine. Freshly voided urine is clear. Cloudy urine may indicate an infection. Specific Gravity The usual range of specific gravity of urine is 1.010 to 1.025; this is a measure of the dissolved materials in urine. (The specific gravity of distilled water is 1.000.) The higher the specific gravity, the more dissolved material is present. Spe- cific gravity of urine is a measure of the concentrating ability of the kidneys; the kidneys must excrete the waste products that are constantly formed in as little water as possible. pH The pH range of urine is 4.6 to 8.0, with an average of 6.0. Diet has the greatest influence on urinary pH. A vegetarian diet results in a more alkaline urine; a high-protein diet results in a more acidic urine. Constituents Urine is approximately 95 percent water, which is the sol- vent for waste products and salts. Nitrogenous wastes include urea, creatinine, and uric acid. Urea is formed by liver cells when excess amino acids are deaminated to be used for energy production. Creatinine comes from the metabolism of creatine phosphate, an energy source in muscles. Uric acid comes from the metabolism of nucleic acids—that is, the breakdown of DNA and RNA. Aging and the Urinary System With age, the number of nephrons in the kidneys decreases, often to half the original number by age 70 or 80. The GFR also decreases; this is in part a consequence of arteriosclero- sis and diminished renal blood flow. The urinary bladder decreases in size, and the tone of the detrusor muscle decreases. This may result in the need to urinate more frequently or in residual urine in the bladder after voiding. Elderly people are also more subject to infections of the urinary tract, and the changes of aging may influence medication therapy for elderly people (Gerontological Issues Box 34–1). BOX 34–1 Age-related Renal Changes Certain changes typically occur in the renal system as people age. They include the following: • The renal mass becomes smaller. • Renal flow decreases by 50 percent, with subsequent decreased glomerular filtration rate. • Tubular function and the exchange of substances decrease. • Bladder muscles weaken and bladder capacity decreases, leading to increased frequency and nocturia. • The voiding reflex is delayed. Also, keep in mind that most drugs are excreted through the kidneys. Consequently, changes in renal function become a se- rious consideration for older adults who need drug therapy. De- creased renal function could slow the excretion of some drugs, keeping them in the body longer. This can increase the risk of adverse drug reactions, such as toxicity and overdose. It is important to monitor kidney function (such as creatinine and blood urea nitrogen levels) in an older person receiving drug therapy. NURSING ASSESSMENT Health History When recording a patient’s health history, the following minimum information should be obtained: ■ History of renal or urinary problems ■ Family history of urinary disorders, diabetes, or hypertension (diabetes and hypertension are major contribut- ing factors to renal failure) ■ Presence of pain or burning either with voiding or over the kidney ■ Voiding pattern ■ New onset of symptoms of edema, shortness of breath, weight gain, abdominal fullness, or other symptoms of renal failure (see Chapter 35) ■ Current medications, including over-the-counter medications and herbs ■ Functional ability to take care of toileting needs Williams_ch34_571-587 12/6/02 3:00 PM Page 577 Copyright © 2003 F.A. Davis Company 578 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM ■ Fluid intake and diet ■ Age Lung Sounds If the patient retains more fluid than the heart can effec- tively pump, fluid may be retained in the lungs. This is manifested as crackles, which are popping sounds heard on in- spiration and sometimes on expiration when the chest is auscultated. Wheezes may also be present. New-onset crackles and wheezes should be reported to a physician. (See Chapter 26 for assessment of the respiratory system.) Edema Fluid retention may be manifested as edema (excess fluid in tissues). The nurse assesses and documents the degree and location of edema. Edema may be generalized in renal failure. The nurse also looks for edema in the area around the eyes (periorbital edema). Assessment of edema is discussed in detail in Chapter 15. Daily Weights Weight is the single best indicator of fluid balance in the body. Patients with renal disease often have fluid imbal- ances. The patient should be weighed at the same time each day, in the same or similar clothing. The nurse is careful not just to document the weight, but also to look at trends in weight gain or loss. If the patient’s weight is steadily in- creasing, fluid retention is suspected and should be reported. A patient undergoing diuresis is expected to have decreas- ing weights. Intake and Output All patients with renal disease should have careful meas- urement of intake and output. Individual voidings are analyzed for amount and recorded. The nurse measures and records all liquids taken in, including oral, intravenous, ir- rigation, tube feeding, and other fluids. Output includes urine, emesis, nasogastric effluent, wound drainage if it is copious, and any other drainage. As part of measuring output, the nurse should examine the urine for any abnormali- ties. Often problems show up readily in the urine, with changes such as hematuria, cloudiness, and foul odor seen with infection or concentrated dark-amber urine seen with dehydration. Intake and output totals are analyzed and recorded every 8 or 12 hours or more often for unstable patients. As with daily weights, the nurse notes trends in retention or loss of fluid and reports significant changes to the physician. Ac- To find your kidneys, put your hands on your hips with your thumbs pointing back and upward. Your thumbs are pointing to the bot- tom of the kidneys. This is called the flank area. Pain in this area is called flank pain. Any symptoms should be further assessed using the WHAT’S UP? format found in Chapter 1. If the patient has impaired kidney function or is in kidney failure, a complete head-to-toe assessment is needed, because kidney failure (renal failure) affects every system of the body. (See Chapter 35.) Physical Assessment The nurse first inspects the skin for color and texture. A patient with chronic renal failure may have a yellow or gray cast to the skin. The presence of crystals on the skin is called uremic frost and is a late sign of waste products build- ing up in the blood (uremia). When the wastes are not fil- tered by the kidneys, they can come out through the skin and look like a coating of frost. Palpation and percussion of the kidneys is done by physi- cians and advance practice nurses. Gentle palpation and percussion of the bladder may be done by the licensed prac- tical nurse/licensed vocational nurse (LPN/LVN) if urine retention is suspected. If the patient has a feeling of fullness but is unable to urinate, the nurse gently palpates the supra- pubic area for a full bladder. Normally the bladder is not palpable. The bladder may also be percussed. The percussion note sounds dull over a fluid-filled bladder. Most assessment of the urinary system is done using in- direct measures. Assessment of vital signs, lung sounds, edema, daily weights, and intake and output can provide valuable data related to urinary function. Vital Signs If renal disease is suspected, blood pressure should be assessed and documented while the patient is lying, sitting, and standing. An increase in blood pressure is commonly seen with renal disease. A drop in blood pressure accompa- nied by a rise in pulse rate as the patient rises to sitting or standing positions is called orthostatic or postural hypotension and may indicate fluid deficit. (See Chapter 15 for a more complete discussion of orthostatic hypotension.) A rapid respiratory rate may indicate fluid retention in the lungs. uremia: ur—urine ϩ emia—blood Mr. Nolan It is the end of the shift. As you empty Mr. Nolan’s indwelling catheter bag, you find that it has only 50 mL of concentrated urine in it. What do you do? Answer at end of chapter. hematuria: hemat—blood ϩ uria—urine Williams_ch34_571-587 12/6/02 3:00 PM Page 578 Copyright © 2003 F.A. Davis Company Chapter 34 URINARY SYSTEM FUNCTION, ASSESSMENT, AND THERAPEUTIC MEASURES 579 curate documentation is vital, because the physician may base medication and intravenous fluid orders on intake and output results. DIAGNOSTIC TESTS OF THE RENAL SYSTEM Laboratory Tests Urine Tests URINALYSIS. A urinalysis (urine analysis) is a commonly performed diagnostic test for the renal system. The results of the urinalysis give information regarding kidney function and various body functions. Table 34–2 lists normal and abnormal findings on a urinalysis. To collect a voided specimen for urinalysis, the nurse has the patient wash the perineum using soap and water or a special towelette from a clean-catch midstream urine collection kit. Women should be directed to wash from the front to the back of the perineum. The patient is instructed to begin to void into the toilet, and then move the collection container under the stream, and then finish voiding into the toilet. This is called a clean-catch midstream specimen. It is used to obtain the cleanest possible specimen. Female patients should be told to separate the labia with one hand and keep it separated while washing and collecting the specimen to decrease the risk of contamination of the specimen. If the female patient is menstruating, this should be specified on the laboratory form. A tampon may be used to prevent contamination of the specimen. The un- circumcised male patient should be directed to retract the foreskin with one hand and keep it retracted while cleans- ing and voiding. At least 10 mL of urine should be collected. If a urinalysis is ordered for a patient with a urinary catheter, the nurse obtains the urine specimen. This specimen is considered sterile because it is coming directly from the bladder into the urinary catheter tubing. To obtain the specimen, wear clean gloves and use an alcohol swab to clean the sample port on the catheter tubing. Insert the needle of a syringe (usually 10 mL) into the port and with- draw urine from the tubing into the syringe. Then empty the urine from the syringe into a collection container and safely dispose of the syringe. URINE CULTURE. A urine culture is done to determine the number of bacteria present in the urine and to identify the organism causing infection in the urine. The urine should be collected before antibiotic treatment is begun to avoid affecting results. The midstream clean-catch system is used to obtain voided specimens. A physician may order a catheterized specimen if there is a risk of contamination from the vagina, if a female patient is menstruating, or if the patient is incontinent. As a general rule, a bacterial count Test Normal Results Abnormal Results and Significance Color of urine Odor of urine pH Specific gravity Protein Glucose Ketones Bilirubin Nitrite Leukocyte esterase Red blood cells White blood cells Casts hpf ϭ high-power field; WBC ϭ white blood cells. TABLE 34–2 Urinalysis Results Pale yellow to amber Aromatic 4.6–8.0 1.010–1.025 0–18 mg/dL None None None Negative Negative 0–4/hpf 0–5/hpf None to occasional hyaline cast Dark-amber urine suggests dehydration. Yellow-brown to green urine indicates excessive bilirubin. Cloudiness of freshly voided urine indicates infection. Nearly colorless urine is seen with a large fluid intake or diabetes insipidus. With infection, urine becomes foul smelling. In diabetic ketoacidosis, the urine has a fruity odor. Urine that has been standing for a while develops a strong ammonia smell. The pH is greatly affected by the food eaten. pH below 4.6 is seen with metabolic and respiratory acidosis. pH above 8.0 is seen when urine has been standing or with infection because bacteria decompose urea to form ammonia. Low specific gravity indicates excessive fluid intake or diabetes insipidus. High specific gravity is seen with dehydration. A specific gravity fixed at 1.010 indicates kidney dysfunction. Persistent proteinuria is seen with renal disease from damage to the glomerulus. Intermittent protein in the urine can result from strenuous exercise, dehydration, or fever. As a general rule, protein in the urine is a significant sign of renal problems. Glucose in the urine indicates diabetes mellitus, excessive glucose intake, or low renal threshold for glucose reabsorption. Ketones in the urine indicate diabetes mellitus with ketonuria or starvation from breakdown of body fats into ketones. Bilirubin in the urine indicates liver disorders causing jaundice. Bilirubin may appear in the urine before jaundice is visible. Nitrites in the urine indicate infection in the urine. Bacteria in the urine convert nitrate to nitrite, which gives a positive reading. A positive leukocyte esterase in the urine indicates infection in the urine. It determines the presence of an enzyme released by WBCs in the urine. Blood in the urine may be caused by kidney stones, infection, cancer, renal disease, or trauma. WBCs in the urine indicate infection or inflammation in the urinary tract. Casts are formed when abnormal urine contents settle into molds of the renal tubules and may be made of protein, WBCs, RBCs, or bacteria. A few hyaline casts may be found in normal urine. The presence of casts generally indicates renal damage or infection. Williams_ch34_571-587 12/6/02 3:00 PM Page 579 Copyright © 2003 F.A. Davis Company 580 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM of 100,000 or more per milliliter of urine indicates a urinary tract infection. An amount less than that may result from contamination during specimen collection. The urine is cultured to grow and identify the kind of bacteria present. Often a sensitivity test is also ordered to determine what kind of antibiotic will be most effective in eradicating the offending bacteria. Renal Function Tests A number of blood tests reflect kidney function. If the kidneys are not functioning adequately, these test results will be elevated. SERUM CREATININE. Creatinine is a waste product from muscle metabolism and is released into the bloodstream at a steady rate. Creatinine levels are a very good indicator of kidney function (normal: 0.6 to 1.5 mg/dL). A serum creatinine level above 1.5 mg/dL means there is kidney dysfunction. The higher the creatinine level, the more impaired the kidney function. BLOOD UREA NITROGEN. Urea is a waste product of protein metabolism. The blood urea nitrogen (BUN; normal: 8 to 25 mg/dL) is not as sensitive an indicator of kidney function as the creatinine level. This is because it is readily affected by increased protein intake, dehydration, and other factors in the body. An elevated BUN level can be caused by the following factors: ■ Kidney dysfunction or failure ■ Decreased kidney blood supply, such as when the patient is in a state of shock or in severe heart failure ■ Dehydration, because the loss of water makes the blood more concentrated (decreased BUN level is seen with overhydration) ■ High-protein diet, because urea formation increases ■ Gastrointestinal bleeding, because blood is absorbed as protein and converted into urea ■ Steroid use, because steroids increase the rate of protein breakdown in the body URIC ACID. Uric acid is an end product of purine metabolism and the breakdown of body proteins. The uric acid is not as diagnostic as creatinine because many factors can cause an elevated uric acid level (normal: 2 to 7 mg/dL). An elevated uric acid level can be caused by the following: ■ Kidney disease ■ Gout (patients with gout metabolize uric acid abnormally) ■ Malnutrition ■ Leukemia ■ Use of thiazide diuretics (because of impairing uric acid clearance by the kidney) CREATININE CLEARANCE. The creatinine clearance test measures the amount of creatinine cleared from the blood in a specified period by comparing the amount of creatinine in the blood with the amount of creatinine in the urine. It is an excellent indicator of renal function. To carry out the test, urine is collected for a 24-hour period, and a sample for serum creatinine is collected some- time during the 24 hours. The following procedure should be followed: 1. When the test is begun, the patient is directed to void and discard that urine. 2. Urine is collected for 24 hours, keeping the urine in a large container provided by the laboratory. The container is kept on ice. 3. Twenty-four hours after the test was begun, the patient is instructed to void again. This urine is added to the collection container. 4. The laboratory collects a serum creatinine during this 24- hour period. The creatinine clearance is computed in the laboratory and is expressed in volume of blood that is cleared of creatinine in 1 minute. Normal is 85 to 125 mL. A minimum creatinine clearance of 10 mL per minute is needed to live without dialysis. A handy approximation to determine kidney function is to equate the creatinine clearance result to percent of renal function. For ex- ample, a creatinine clearance of 100 mL per minute ϭ 100 percent renal function, 30 mL per minute ϭ 30 percent renal function, and 5 mL per minute ϭ 5 percent renal function. Radiological Studies Kidney-Ureter-Bladder A kidney-ureter-bladder (KUB) is an x-ray examination of the named structures. This test is also known as a flat plate of the abdomen. It displays the outline of the renal structure and can show tumors, swollen kidneys, and calcium-based kidney stones. No special care is necessary for this test. Intravenous Pyelogram The intravenous pyelogram (IVP) is a common test. During the test, a radiopaque dye is injected into a large vein. The dye is cleared from the blood by the kidneys. Because the x- rays cannot penetrate the dye, the dye outlines the renal structures. Radiographs are taken at frequent intervals to see the dye filling the renal pelvis and going down the ureters into the bladder (Fig. 34–3). In preparation for an IVP, the patient takes laxatives to cleanse the bowel the day before the test, following agency policy. The patient is allowed nothing by mouth (NPO) after midnight the evening before the test. As with all con- trast studies, the patient should be questioned for allergies to iodine and shellfish before the test. The dye can cause allergic and anaphylactic reactions in people who are allergic to these substances, although this problem is less common since the introduction of a newer radiopaque dye. The patient should also be warned about a warm, flushing sensa- pyelogram: pyelo—pelvis of the kidney ϩ gram—radiograph Williams_ch34_571-587 12/6/02 3:00 PM Page 580 Copyright © 2003 F.A. Davis Company [...]... procedure that involves a rigid or fiberoptic instrument (cystoscope) inserted into the bladder through the urethra A cytoscopy: cysto—bladder ϩ scopy—to examine Copyright © 2003 F.A Davis Company 582 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM light at the end of the instrument allows a physician to visualize the interior of the bladder Commonly a pyelogram is done as well This involves insertion of... unless contraindicated by other medical problems This also simplifies measuring intake A sport bottle helps to keep water at hand while moving about the home Copyright © 2003 F.A Davis Company 586 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM subsequent swelling may make it impossible to pull the foreskin over the glans penis later This can then cause ischemia of the glans penis, which is an emergency... T I O N S 1 A home health nurse visits a patient who is 82 years old He uses a cane and is not incontinent Which one of the following interventions should be included in the plan of care, based on an understanding of normal age-related changes of the urinary system, to promote his safety? a Encourage fluids after 6 P.M b Limit fluids to 1000 mL per day c Provide a nightlight in the bathroom d Provide... PATHOPHYSIOLOGY Pyelonephritis is infection of the kidneys Pathophysiology includes formation of small abscesses throughout the kidney and gross enlargement of the Copyright © 2003 F.A Davis Company 590 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM kidney The cause is usually an ascending bacterial infection On occasion, kidney infection is caused by bacteria spreading from a distant site through the bloodstream... Ureteral stone Bladder stones Urethral stone urethroplasty: urethro—urethra ϩ plasty—surgical repair F i g u r e 35–1 Location of calculi in the urinary tract Copyright © 2003 F.A Davis Company 592 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM for stone formation Additional causes of calcium stones include dietary factors (see Nutrition Notes Box 35–2) Excessive amounts of calcium in the water in some... activity increase, and diet changes if ordered EVALUATION Patient outcomes are met if pain is controlled, fever and other complications are recognized and reported promptly, and the patient verbalizes understanding of self-care measures to prevent recurrent stones Hydronephrosis Hydronephrosis is a condition that results from untreated obstruction in the urinary tract It is usually treatable once the... or hydronephrosis: hydro—pertaining to water ϩ nephrosis— degenerative change in kidney oliguria: olig—small ϩ uria—urine anuria: an—without ϩ uria—urine Copyright © 2003 F.A Davis Company 594 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM F i g u r e 35–3 Hydronephrosis Progressive thickening of bladder wall and dilation of ureters and kidneys results from obstruction of urine flow Stent in place... W-neobladder After this surgery the patient can void through the urethra, though incontinence may be a problem and intermittent catheterization may be needed Copyright © 2003 F.A Davis Company 596 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM BOX 35–5 A Isolated segment of ileum with ureters implanted in posterior portion Stoma on abdomen Peristalsis Stoma sutured to body wall Ureters implanted into... creatinine clearance tests are then done to confirm the presence and extent of diabetic nephropathy nephropathy: nephro—pertaining to the kidney ϩ pathy— disease Copyright © 2003 F.A Davis Company 598 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM Oral cavity Stomatitis Bad taste in mouth Cardiovascular system Hypertension Heart failure Dysrhythmias Gastrointestinal system Anorexia Nausea Vomiting Gastrointestinal... Teaching the patient about preventing glomerulonephritis is important Antibiotics for diagnosed streptococcal throat infections should be taken for prevention Copyright © 2003 F.A Davis Company 600 Unit IX UNDERSTANDING THE RENAL AND URINARY SYSTEM RENAL FAILURE Renal failure, also called kidney failure, is diagnosed when the kidneys are no longer functioning adequately to maintain normal body processes . Ur Ur inar inar y S y S ystem ystem Williams_ch34_5 71- 587 12 /6/02 2:59 PM Page 5 71 Copyright © 2003 F.A. Davis Company Williams_ch34_5 71- 587 12 /6/02 2:59 PM Page 572 Copyright © 2003 F.A. Davis. renal failure? 10 . What are common symptoms experienced by the patient in renal failure? 11 . What nursing care should be given to patients in renal failure and with a hemodialysis blood access site? 12 usual range of specific gravity of urine is 1. 010 to 1. 025; this is a measure of the dissolved materials in urine. (The specific gravity of distilled water is 1. 000.) The higher the specific gravity,

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