PrepU Patho Chapter 32 Structure and Function of the Kidney

Clients with CKD are at risk for demineralization of their bones since they are no longer able to: stimulate bone osteoclastic production. synthesize erythropoietin. transform vitamin D to its active form. excrete bicarbonate effectively.

transform vitamin D to its active form. The kidneys aid in calcium metabolism by activating vitamin D after it is chemically converted by the liver. Bicarbonate buffering is unrelated to activation of vitamin D. Bone marrow is stimulated by the synthesis of erythropoietin to form red blood cells, which is unrelated to calcium levels.

The nurse is caring for a client who is diagnosed with gout. Which laboratory study does the nurse monitor to monitor this condition?

uric acid levels rationale: Uric acid is a product of purine metabolism. Excessively high blood levels (i.e., hyperuricemia) can cause gout, and excessive urine levels can cause kidney stones.

A client in the hospital is frustrated at the inconvenience of having to collect his urine for an entire day and night as part of an ordered 24-hour urine-collection test. The client asks the nurse why the test is necessary since the client provided a single urine sample 2 days prior. How could the nurse best respond?

"Often when an abnormal substance shows up in a urine test, a 24-hour urine collection is needed to determine exactly how much is present in your urine." rationale: 24-hour urine tests are often used to quantify the amount of substances, such as proteins, that an individual's kidneys are spilling. Single urine samples are able to assess more parameters than just the presence of bacteria, and they are sufficient in quantity to detect numerous substances such as glucose.

A nurse is teaching a client scheduled for a cystoscopy about the procedure. Which statement made by the client verifies that the teaching has been successful?

"The doctor will insert a lighted tube through my urethra into my bladder in order to inspect the inside of the bladder." rationale: Cystoscopy provides a means for direct visualization of the urethra, bladder, and ureteral orifices. It relies on the use of a cystoscope, an instrument with a lighted lens. The cystoscope is inserted through the urethra into the bladder. Biopsy specimens, lesions, small stones, and foreign bodies can be removed from the bladder.

The nurse is educating a client about renal disease. Which percentage of cardiac output perfuses the kidneys? 10% to 15% 22% to 25% 27% to 30% 15% to 20%

22-25% In the adult, the kidneys are perfused with 1000 to 1300 mL of blood per minute, or 22% to 25% of the cardiac output; 10% to 15% and 15% to 20% represent a decreased percentage; 27% to 30% is an increased percentage.

The nurse is preparing the client with suspected bladder cancer for a biopsy via cystoscopy. What does the nurse teach the client about cystoscopy?

A flexible, lighted tube will be inserted into the bladder and a tissue sample will be taken. rationale: Cystoscopy allows direct visualization of the urethra, bladder, and ureteral orifices. A cystoscope, an instrument with a lighted lens, is inserted through the urethra into the bladder. Biopsy specimens, lesions, small stones, and foreign bodies can be removed from the bladder.

When caring for a client with dehydration, the nurse anticipates the client will have an alteration in which substance in the blood? Erythropoietin Bicarbonate Iric acid Blood urea nitrogen

BUN During periods of dehydration, the blood volume and GFR drop, and BUN levels increase. The renal tubules are permeable to urea, which means that the longer the tubular fluid remains in the kidneys, the greater the reabsorption of urea into the blood.

A nurse is evaluating a client's morning laboratory values. Which result requires that the nurse notify the health care provider? Creatinine: 10.6 mg/dL (937.04 µmol/L) Sodium: 148 mEq/L (148 mmol/L) Blood urea nitrogen: 20.0 mg/dL (7.14 mmol/L) Potassium: 3.4 mEq/L (3.4 mmol/L)

Creatinine: 10.6 mg/dL (937.04 µmol/L) A rise in the serum creatinine level to three times its normal value suggests that there is a 75% loss of renal function, and with creatinine values of 10 mg/dL or more, it can be assumed that approximately 90% of renal function has been lost.

The client with chronic kidney disease asks the nurse why he must take active vitamin D (calcitriol) as a medication. What is the most appropriate response by the nurse?

In renal disease, vitamin D is unable to be transformed to its active form rationale: Cholecalciferol and ergocalciferol must undergo chemical transformation to become active: first to 25-hydroxycholecalciferol in the liver and then to 1,25-dihydroxycholecalciferol in the kidneys. Individuals with end-stage renal disease are unable to transform vitamin D to its active form and may require pharmacologic preparations of the active vitamin (calcitriol) for maintaining mineralization of their bones.

To treat enuresis in a young girl, her pediatrician prescribes desmopressin, an antidiuretic hormone (ADH) nasal spray, before bedtime. Which rationale for this treatment is the most likely? It causes tubular cells to lose their water permeability. It leads to the production of dilute urine. It removes water from the filtrate and returns it to the vascular compartment. It lessens the amount of fluid entering the glomerulus.

It removes water from the filtrate and returns it to the vascular compartment. ADH maintains extracellular volume by returning water to the vascular compartment. This leads to the production of concentrated urine by removing water from the tubular filtrate. In exerting its effect, ADH produces a marked increase in water permeability in tubular cells.

The anemia that occurs with end-stage kidney disease is often caused by the kidneys themselves. What loss of function in the kidney results in anemia of end-stage kidney disease? Produce erythropoietin Produce angiotensin Produce renin Inactivate vitamin D

Produce erythropoietin Persons with end-stage kidney disease often are anemic because of an inability of the kidneys to produce erythropoietin. This anemia usually is managed by the administration of a recombinant erythropoietin (epoetin alfa), produced through DNA technology, to stimulate erythropoiesis.

The nurse is caring for a client with kidney disease who has an estimated glomerular filtration rate of 75 mL/minute. The nurse interprets this data in which way? The client's low blood pressure is causing the reduced glomerular filtration rate. The client has reduced glomerular filtration, reflecting damage to the kidney. The rate is normal. The client's diabetes is causing the reduced glomerular filtration rate.

The client has reduced glomerular filtration, reflecting damage to the kidney. Approximately 125 mL of filtrate is formed each minute. This is called the glomerular filtration rate (GFR). This rate can vary from a few milliliters per minute to as high as 200 mL/minute.

A medical client's routine urinalysis includes the following data: Casts: positive Red blood cells: negative Crystals: negative White blood cells: negative Epithelial cells: few Which interpretation of these findings is the most plausible? The client's urine contains excessive protein. The client has no indication of renal pathology. Urine specific gravity is likely to be lower than normal. The client may have leukopenia.

The client's urine contains excessive protein. The presence of casts is associated with proteinuria, such as that which accompanies nephrotic syndrome. An absence of white cells is expected, and does not denote leukopenia. There is no clear indication of the specific gravity from these findings.

The nurse is teaching a group of nursing students about the mechanism of action of common diuretics. What best reflects the mechanism of these drugs? They block uric acid and glucose in the renal tubules. They block the reabsorption of sodium and chloride in the nephron. They promote release of aldosterone from the adrenal glands. They enhance absorption of potassium in the loop of Henle.

They block the reabsorption of sodium and chloride in the nephron. Most diuretics share the same mechanism of action—blockade of sodium and chloride reabsorption. By blocking the reabsorption of these solutes, diuretics create an osmotic pressure gradient within the nephron that prevents the passive reabsorption of water. Thus, diuretics cause water and sodium to be retained in the nephron, promoting the excretion of both.

The nurse is reviewing the results of a renal client's laboratory results. This client's urine specific gravity allows the nurse to assess the kidneys' ability to: excrete potassium. excrete excess hydrogen ions. concentrate protein. concentrate urine.

concentrate urine Urine specific gravity is used to assess the kidneys' ability to concentrate urine and provides a valuable index of the hydration status and functional ability of the kidneys. Specific gravity does not evaluate electrolyte or acid-base functions of the kidneys. It is not affected by protein levels.

Urine specific gravity is normally 1.010 to 1.025 with adequate hydration. When there is loss of renal concentrating ability due to impaired renal function, low concentration levels are exhibited. When would the nurse consider the low levels of concentration to be significant?

first void in morning rationale: With diminished renal function, there is a loss of renal concentrating ability, and the urine specific gravity may fall to levels of 1.006 to 1.010 (usual range is 1.010 to 1.025 with normal fluid intake). These low levels are particularly significant if they occur during periods that follow a decrease in water intake (e.g., during the first urine specimen on arising in the morning).

The nurse would be most concerned when the glomerular filtrate contains: protein potassium water sodium

protein rationale: The glomerular filtrate has a chemical composition similar to plasma, but it contains almost no proteins because large molecules do not readily cross the glomerular wall. Potassium, sodium, and water would be filtered.

In the intensive care unit (ICU), the nurse is caring for a trauma client who has abdominal injuries, is beginning to have a decrease in BP and increased pulse rate, and is pale with diaphoretic skin. The nurse is assessing the client for hemorrhagic shock. If the client is in shock, the nurse would expect to find:

significant decrease in urine output due to decrease in renal blood flow. rationale: During periods of strong sympathetic stimulation, such as shock, constriction of the afferent arteriole causes a marked decrease in renal blood flow and thus glomerular filtration pressure. Consequently, urine output can fall almost to 0. Unless the injury is specific to the kidney, the client will not have blood in urine and urine production will not be excessive. Flank pain is associated with obstruction due to stone formation. The GFR will decrease rather than increase.

A client with end-stage kidney disease has developed anemia. The nurse teach this client that the reason anemia has developed is:

the damaged kidney is unable to produce erythropoietin. rationale: Persons with end-stage kidney disease often are anemic because of an inability of the kidneys to produce erythropoietin, the hormone that regulates the differentiation of red blood cells in the bone marrow.

A client is scheduled for a creatinine clearance test to measure the glomerular filtration rate (GFR). The client asks the nurse what this test is used for. What is the nurse's best response?

"This test provides a gauge of renal function." rationale: The GFR provides a gauge of renal function. The GFR is the amount of filtrate that is formed each minute as blood moves through the glomeruli. The clearance rate for creatinine is the amount that is completely cleared by the kidneys in 1 minute.

The nurse is assigned multiple clients with anemia. Which client may be experiencing a failure of the body to produce erythropoietin and thus may require supplemental injections of this hormone?

Client with history of chronic kidney failure Erythropoietin is a glycoprotein hormone that is produced by fibroblasts in the kidney and regulates the production of red blood cells in the bone marrow. Persons with end-stage kidney disease often are anemic because the kidneys can no longer produce erythropoietin. Impaired oxygenation of tissues due to cardiac or pulmonary disease stimulates the kidney to produce erythropoietin. A client whose recent wound is healing is likely not experiencing anemia related to loss of erythropoietin production. Some clients experience blood loss after surgery, but this should stimulate the kidney to produce more erythropoietin.

What contributes to impairment in renal function in aging?

Decrease in functioning nephrons rationale: Overall, there is a decreased kidney mass with aging, predominately in the renal cortex. There is a generalized decrease in functioning nephrons. In fact, adults tend to lose approximately 10% of their nephrons for each decade beginning at 40 years of age. Proximal tubule function does not increase and neither does the glomerular filtration rate.

The nurse and nursing student are caring for a client with kidney dysfunction who requires a test to determine glomerular filtration rate. The nurse recognizes that the student understands the test when the student states:

I will need to start a 24-hour urine collection. rationale: The test for glomerular filtration requires 24-hour urine collection, with blood being drawn when the urine collection is completed. In another method, two 1-hour urine specimens are collected, and a blood sample for creatinine is drawn in-between.

Mannitol has been ordered for a client with increased intracranial pressure. The nurse plans to administer this drug using which method? Orally Intravenously Subcutaneous injection Intramuscular injection

IV Mannitol is used mainly to reduce increased intracranial pressure but is occasionally used to promote prompt removal of toxins. Because it is not absorbed, mannitol must be given intravenously to act as a diuretic.

When teaching the client with gout about the cause of the disease, which cause should the nurse relate?

Increased levels of uric acid in the blood cause gout. rationale: Uric acid is a product of purine metabolism. High blood levels of uric acid (hyperuricemia) can cause gout, and excessive urine levels can cause kidney stones.

Which factor is likely to result in decreased renal blood flow? dopamine nitric oxide stimulation of the sympathetic nervous system prostaglandins

Stimulation of the sympathetic nervous system rationale: Sympathetic nervous system (SNS) stimulation results in decreased renal blood flow by vasoconstriction. Dopamine, nitric oxide, and prostaglandins are all vasodilators.

The nurse is caring for a client who has produced an average of 20 mL/hour for the previous day. The nurse recognizes this compares in which way to the normal urine output? The normal kidney produces an average 3000 mL of urine daily. The kidneys should produce about 1.5 L of urine each day. The kidneys should produce a minimum of 10 mL/hr over one day. This represents normal urinary output for 24 hours.

The kidneys should produce about 1.5 L of urine each day. The kidneys normally produce approximately 1.5 L or 1500 ml of urine each day.

Which medication may be responsible for a client developing increased uric acid levels by decreasing ECF volume?

Thiazide diuretics rationale: Because of its effect on uric acid secretion, aspirin is not recommended for treatment of gouty arthritis. Thiazide and loop diuretics also can cause hyperuricemia and gouty arthritis, presumably through a decrease in ECF volume and enhanced uric acid reabsorption.

It is known that high levels of uric acid in the blood can cause gout, while high levels in the urine can cause kidney stones. What medication competes with uric acid for secretion into the tubular fluid, thereby reducing uric acid secretion? Acetaminophen Naproxen Ibuprofen Aspirin

aspirin Small doses of aspirin compete with uric acid for secretion into the tubular fluid and reduce uric acid secretion. Large doses compete with uric acid for reabsorption and increase uric acid excretion in the urine.

A client has been prescribed a drug that is not removed quickly by renal filtration. The drug likely has this quality because it is: bound to plasma proteins. water soluble. a hydrophilic weak base. a hydrophilic weak acid.

bound to plasma proteins If the drug is bound to plasma proteins, it will not enter the filtrate. Hydrophilic acids and bases are easily eliminated by renal filtration. A water soluble drug is not immune to renal filtration.

When the urologist wants to directly visualize the bladder, urethra, and ureteral orifices, what diagnostic test would he use? Cystoscopy Laparoscopy Echocardiogram Ultrasonography

cytoscopy Cystoscopy provides a means for direct visualization of the urethra, bladder, and ureteral orifices. It relies on the use of a cystoscope, an instrument with a lighted lens. None of the other tests provide direct visualization of the bladder, urethra, and ureteral orifices.

A client has just been admitted to the emergency department after sustaining severe injuries and massive blood loss following a motor vehicle accident. The nurse predicts that the client's glomerular filtration rate will:

decrease rationale: Although nearly all the blood that enters the kidney flows through the cortex, less than 10% passes into the medulla and only about 1% moves into the papillae. Under conditions of decreased perfusion or increased sympathetic nervous system stimulation, blood flow is redistributed away from the cortex toward the medulla. This redistribution of blood flow decreases glomerular filtration while maintaining the urine-concentrating ability of the kidneys, a factor that is important during conditions such as shock. With decreasing flow, the filtration rate will decrease to adapt perfusion and maintain function.

The nurse is caring for a client who has sustained a cervical spinal cord injury with resulting muscle wasting due to immobility. Which alteration in the laboratory tests does the nurse recognize is consistent with decreased muscle mass? Decreased calcium levels Increased phosphate levels Increased blood urea nitrogen levels Decreased creatinine levels

decreased cratinine Creatinine is a product of creatine metabolism in muscles; its formation and release are relatively constant and proportional to the amount of muscle mass present.

A client's most recent blood work reveals a blood urea nitrogen (BUN) level of 36 mg/dL (12.85 mmol/L). Which factor may have contributed to this finding? dehydration increased salt intake parasympathetic stimulation action of antidiuretic hormone

dehydration rationale: During periods of dehydration, the blood volume and glomerular filtration rate drop, and BUN levels increase. Increased salt intake, parasympathetic stimulation, and the action of antidiuretic hormone do not normally result in an increase in BUN.

In the emergency department, a client arrives following a car accident. His pulse is 122; BP 88/60; respiration is 18 bpm. Urine output is 4 mL over the first hour on arrival. When in shock, this lower urine output is primarily due to:

innervation of the sympathetic nervous system, causing constriction of the afferent arteriole rationale: During periods of strong sympathetic stimulation, such as shock, constriction of the afferent arteriole causes a marked decrease in renal blood flow, and thus glomerular filtration pressure. Consequently, urine output can fall almost to zero. The location of the glomerulus between two arterioles allows for maintenance of a high-pressure filtration system. The glomerular filtrate has a chemical composition similar to plasma, but contains almost no proteins because large molecules do not readily pass through the openings in the glomerular capillary wall.

The nurse and nursing student are caring for a client with a condition causing deficiency of ADH. The nurse recognizes that the student understands the origin of this process when the student states ADH is produced in which area? Osmoreceptors Renal cortex Pituitary gland Adrenal gland

pituitary gland ADH assists in maintenance of the extracellular fluid volume by controlling the permeability of the medullary collecting tubules. Osmoreceptors in the hypothalamus sense an increase in osmolality of extracellular fluids and stimulate the release of ADH from the posterior pituitary gland. In exerting its effect, ADH, also known as vasopressin, binds to receptors on the basolateral side of the tubular cells.

An older adult man is brought into the clinic by his daughter, who states, "My father hasn't been himself lately. Now I think he looks a little yellow." What test would the nurse expect to have ordered to check this man's creatinine level? Urine test, first void in morning Serum creatinine BUN level 24-hour urine test

serum creatinine Creatinine is freely filtered in the glomeruli, is not reabsorbed from the tubules into the blood, and is only minimally secreted into the tubules from the blood; therefore, its blood values depend closely on the GFR. A normal serum creatinine level usually indicates normal renal function. If the value doubles, the GFR—and renal function—probably has fallen to half of its normal state. A rise in the serum creatinine level to three times its normal value suggests that there is a 75% loss of renal function. A BUN, 24-hour urine test, and urine test of first void in the morning do not tell the nurse about serum creatinine levels.

A client with Addison disease has been admitted to regulate fluid and electrolyte imbalances. The nurse can anticipate that the client's blood work will show: serum sodium levels have increased. serum calcium levels have decreased. serum potassium levels have increased. serum magnesium levels have decreased.

serum potassium levels have increased. Aldosterone also exerts a strong influence on potassium secretion in the distal and collecting tubules. In the absence of aldosterone, as occurs in Addison disease, potassium secretion is markedly decreased, causing blood levels to increase.

When the glomerular transport maximum for blood glucose is exceeded and its renal threshold has been reached, what happens to the excess glucose?

spills into urine rationale: When the substance (such as blood glucose) exceeds the number of carrier proteins available for transport, the transport maximum has been exceeded, the renal threshold is reached, and the substance will spill (not reabsorb) into the urine. Sodium cotransport helps to move the substance back into the tubule.