fluid and electrolyte homeostasis and imbalances

A patient has a positive Chvostek sign. The nurse interprets this as a sign of a. hypercalcemia. b. hypermagnesemia. c. decreased neuromuscular excitability. d. increased neuromuscular excitability.

ANS: D Positive Chvostek sign indicates increased neuromuscular excitability, which can be caused by hypocalcemia, hypomagnesemia, or other factors. Hypercalcemia and hypermagnesemia cause decreased neuromuscular excitability and do not cause positive Chvostek sign. Hypokalemia and hyperkalemia cause skeletal muscle weakness and do not cause positive Chvostek sign.

Effects of hypernatremia on the central nervous system typically include a. confusion. b. excitation. c. insomnia. d. hallucinations.

ANS: A Hypernatremia causes osmotic shrinking of brain cells, which manifests as confusion or coma. Hypernatremia does not usually cause central nervous system excitation, insomnia, or hallucinations.

An increase in the resting membrane potential (hyperpolarized) is associated with a. hypokalemia. b. hyperkalemia. c. hypocalcemia. d. hypercalcemia.

ANS: A Hypokalemia increases the resting membrane potential. Hyperkalemia results in hypopolarization. Hypocalcemia and hypercalcemia do not affect the resting membrane potential.

What age group has a larger volume of extracellular fluid than intracellular fluid? a. Infants b. Adolescents c. Young adults d. Older adults

ANS: A Infants have a larger volume of extracellular fluid than intracellular fluid. Adolescents, young adults, and older adults have a larger volume of intracellular fluid than extracellular fluid.

Signs and symptoms of clinical dehydration include a. decreased urine output. b. increased skin turgor. c. increased blood pressure. d. decreased heart rate.

ANS: A One clinical manifestation of dehydration is decreased urine output. Skin turgor and blood pressure decrease in clinical dehydration. Heart rate increases in clinical dehydration.

A patient diagnosed with chronic compensated heart failure reports that, "My feet swell if I eat salt but I don't understand why" The nurse's best response is a. "Salt holds water in your blood and makes more pressure against your blood vessels, so fluid leaks out into your tissues and makes them swell." b. "Gravity makes more pressure down by your feet than up at the top of your body, so more fluid leaks into your tissues at your feet and they swell." c. "Salt makes your blood vessels relax and the blood does not flow as fast, so some of it leaks into your tissues and makes swelling." d. "Salt binds to the proteins in your blood and changes the osmotic pressure so more fluid can leak out and stay in the tissues, causing swelling."

ANS: A Salt holds water in the ECV, thus increasing capillary hydrostatic pressure. Gravity leads to feet swelling, but it does not explain what the patient is asking. Salt does not cause vasodilation, nor does it bind to blood proteins and change osmotic pressure.

Signs and symptoms of extracellular fluid volume excess include a. tachycardia. b. increased serum sodium concentration. c. bounding pulse. d. increased hematocrit.

ANS: C Bounding pulse is one of the signs of extracellular fluid volume excess. Tachycardia is one of the signs of extracellular fluid volume deficit. Increased serum sodium concentration is found in hypernatremia. Hematocrit can be decreased with extracellular fluid volume excess.

The inward-pulling force of particles in the vascular fluid is called _____ pressure. a. capillary hydrostatic b. interstitial osmotic c. capillary osmotic d. interstitial hydrostatic

ANS: C Capillary osmotic pressure is the inward-pulling force of particles in the vascular fluid. Capillary hydrostatic pressure is an outward-pulling. The question pertains to vascular fluid rather than interstitial fluid. Interstitial hydrostatic pressure is an outward-pulling force.

The nurse provides teaching regarding dietary intake of potassium to avoid an electrolyte imbalance when a patient a. takes very large doses of vitamin D to supplement during chemotherapy for breast cancer. b. has fatty stools from taking an OTC weight loss product that decreases absorption of fat. c. has chronic heart failure that is treated with diuretics. d. experiences anorexia and chronic oliguric renal failure.

ANS: C Chronic heart failure causes increased secretion of aldosterone, which often causes hypokalemia by increasing renal excretion of potassium; most diuretics used to treat heart failure also increase renal excretion of potassium. Vitamin D and malabsorption of fat decreases absorption of calcium, not potassium. Chronic oliguric renal failure causes decreased excretion of potassium. An anorexic patient with chronic oliguric renal failure should not increase dietary potassium.

Clinical manifestations of hyponatremia include a. weak pulse, low blood pressure, and increased heart rate. b. thirst, dry mucous membranes, and diarrhea. c. confusion, lethargy, coma, and perhaps seizures. d. cardiac dysrhythmias, paresthesias, and muscle weakness.

ANS: C Clinical manifestations of hyponatremia include confusion, lethargy, coma, and perhaps seizures, as they are manifestations of CNS dysfunction. Weak pulse, low blood pressure, and increased heart rate are characteristic of clinical dehydration. Hyponatremia does not cause thirst, dry mucous membranes, and diarrhea. Cardiac dysrhythmias, paresthesias, and muscle weakness are manifestations of electrolyte imbalances.

Clinical manifestations of severe symptomatic hypophosphatemia are caused by a. excess proteins. b. renal damage. c. deficiency of ATP. d. hypocalcemia.

ANS: C Clinical manifestations of severe symptomatic hypophosphatemia are caused by a deficiency of ATP. Phosphate is an important component of ATP, which is the major source of energy for many cellular substances. Severe symptomatic hypophosphatemia does not cause excess protein accumulation, damage the kidneys, or cause hypocalcemia.

What is the most likely explanation for a diagnosis of hypernatremia in an elderly patient receiving tube feeding? a. Too much sodium in the feedings b. Excess of feedings c. Inadequate water intake d. Kidney failure

ANS: C Failure to provide adequate water when a patient is receiving tube feedings could result in hypernatremia. The feedings may have too much sodium, or the patient may be receiving too much feeding solution, but most likely the patient is not receiving enough water. Kidney failure is most likely not the cause of hypernatremia in this patient.

A patient who reports an intestinal fistula also reports feeling "weak and dizzy" when she stands. While taking her blood pressure she becomes temporarily unresponsive but quickly regains consciousness when put into a supine position. What nursing interventions will the nurse implement before calling the physician? a. Sit her up again, with proper support, so you can have an accurate upright blood pressure and heart rate to report. b. Give her a drink of water or juice, talk with her to calm her down, and ask if she slept well last night. c. Give her water or juice and some salty crackers and ask if she has had any diarrhea or vomiting. d. Assess small vein filling time, look for ankle edema, and ask if she had any fluid to drink yet today.

ANS: C Her substantial systolic postural blood pressure decrease with tachycardia and syncope when upright are indicators of ECV deficit and she needs salt and water. Your questions will provide information for her physician regarding the origin of the ECV deficit. She fainted the first time when she sat upright and is likely to faint again, given her upright systolic pressure of 77 mm Hg. She needs salt and water to increase her ECV and sleep quality is not directly related to ECV deficit. Ankle edema is a sign of ECV excess.

Which electrolyte imbalances cause increased neuromuscular excitability? a. Hypokalemia and hyperphosphatemia b. Hyperkalemia and hypophosphatemia c. Hypocalcemia and hypomagnesemia d. Hypercalcemia and hypermagnesemia

ANS: C Hypocalcemia and hypomagnesemia both cause increased neuromuscular excitability. Hypokalemia, hyperkalemia, hypophosphatemia, hypercalcemia, and hypermagnesemia do not cause increased neuromuscular excitability.

A known cause of hypokalemia is a. oliguric renal failure. b. pancreatitis. c. insulin overdose. d. hyperparathyroidism.

ANS: C Insulin overdose causes hypokalemia by shifting potassium into cells. Oliguric renal failure decreases electrolyte excretion. Pancreatitis causes fat malabsorption, which binds calcium and magnesium, but not potassium, in the gastrointestinal tract. Hyperparathyroidism regulates calcium, not potassium.

Which alterations can lead to edema? a. Decreased capillary hydrostatic pressure b. Increased capillary colloid osmotic pressure c. Decreased lymphatic flow d. Decreased capillary membrane permeability

ANS: C Lymphatic obstruction prevents the drainage of accumulated interstitial fluid and proteins, which can lead to severe edema. Decreased capillary hydrostatic pressure would push less fluid into the interstitial space. Increased capillary colloid osmotic pressure would remove fluid from the interstitial space. Decreased capillary membrane permeability would allow less fluid movement into the interstitial space.

Decreased neuromuscular excitability is often the result of a. hypercalcemia and hypermagnesemia. b. hypomagnesemia and hyperkalemia. c. hypocalcemia and hypokalemia. d. hypernatremia and hypomagnesemia.

ANS: A Hypercalcemia and hypermagnesemia result in decreased neuromuscular excitability. Hypomagnesemia, hypocalcemia, and hypomagnesemia result in increased neuromuscular excitability.

Clinical manifestations of extracellular fluid volume deficit include a. weak pulse, low blood pressure, and increased heart rate. b. thirst, dry mucous membranes, and diarrhea. c. confusion, lethargy, coma, and perhaps seizures. d. cardiac dysrhythmias, paresthesias, and muscle weakness.

ANS: A Clinical manifestations of extracellular fluid volume deficit include weak pulse, low blood pressure, and increased heart rate. Extracellular fluid volume deficit does not cause diarrhea. Confusion, lethargy, coma, and perhaps seizures are associated with osmolality imbalances such as hyponatremia. Cardiac dysrhythmias, paresthesias, and muscle weakness are manifestations of electrolyte imbalances.

The electrolyte that has a higher concentration in the extracellular fluid than in the intracellular fluid is _____ ions. a. sodium b. phosphate c. magnesium d. potassium

ANS: A Extracellular fluid has a higher sodium ion concentration than does intracellular fluid. Intracellular fluid has a higher phosphate, magnesium, and potassium ion concentration than does extracellular fluid.

Manifestations from sodium imbalances occur primarily due to a. cellular fluid shifts. b. vascular collapse. c. hyperosmolarity. d. hypervolemia.

ANS: A Sodium imbalances alter osmolality of fluid compartment leading to osmosis of water from the hypo-osmolar compartment to the hyperosmolar compartment. In brain cells, this leads to swelling or shrinkage of cells, and associated manifestations.

he fraction of total body water (TBW) volume contained in the intracellular space in adults is a. three-fourths. b. two-thirds. c. one-half. d. one-third.

ANS: B Approximately two-thirds of TBW is contained inside the cells. Two-thirds, not three-fourths, of TBW is contained inside the cells. Two-thirds, not one-half, of TBW is contained inside the cells. One-third of the TBW is extracellular in adults.

Hypernatremia may be caused by a. decreased aldosterone secretion. b. decreased antidiuretic hormone secretion. c. compulsive water drinking. d. excessive dietary potassium.

ANS: B Decreased antidiuretic hormone secretion (diabetes insipidus) prevents water reabsorption in the kidneys, which creates large volumes of dilute urine and causes hypernatremia. Aldosterone causes sodium and water retention. Compulsive water drinking that overwhelms the kidneys would dilute the blood, causing hyponatremia. Excessive dietary potassium would not affect the serum sodium concentration.

The process responsible for distribution of fluid between the interstitial and intracellular compartments is a. filtration. b. osmosis. c. active transport. d. diffusion.

ANS: B Distribution of fluid between the interstitial and intracellular compartments occurs by the process of osmosis. Filtration is responsible for the distribution of fluid between the vascular and interstitial compartments. Active transport moves ions across membranes, but does not move water. Diffusion involves movement of particles, not movement of water.

Excessive antidiuretic hormone (ADH) secretion can cause _____ concentration. a. increased serum sodium b. decreased serum sodium c. increased serum potassium d. decreased serum potassium

ANS: B Excessive ADH stimulates excessive water reabsorption by the kidneys, which dilutes the blood, thus decreasing the serum sodium concentration. Excessive ADH secretion does not cause increased serum sodium or potassium concentrations, or decreased serum potassium concentration.

Hyperaldosteronism causes a. ECV deficit and hyperkalemia. b. ECV excess and hypokalemia. c. hyponatremia and hyperkalemia. d. excessive water reabsorption without affecting sodium concentration.

ANS: B Hyperaldosteronism causes excessive renal retention of sodium and water and excessive potassium excretion, which lead to ECV excess and hypokalemia. Hyperaldosteronism does not cause ECV deficit, hyperkalemia, hyponatremia, or excessive water reabsorption without affecting sodium concentration.

A patient, who is 8 months pregnant, has developed eclampsia and is receiving intravenous magnesium sulfate to prevent seizures. To determine if her infusion rate is too high, you should regularly a. check the patellar reflex; if it becomes more and more hyperactive, her infusion rate probably is too high and she is at risk for respiratory depression or cardiac arrest. b. check the patellar reflex; if it becomes weak or absent, her infusion rate probably is too high and she is at risk for respiratory depression or cardiac arrest. c. check the patellar reflex; if it stays the same, her infusion rate probably is too high and she is at risk for respiratory depression or cardiac arrest. d. check for seizure activity; if no seizures occur, her infusion rate is correct.

ANS: B Hypermagnesemia causes decreased neuromuscular excitability and testing the patellar reflex can detect that. Hypermagnesemia causes decreased, not increased, neuromuscular excitability. If the patellar reflex stays the same, the infusion rate is therapeutic. Watching for seizure activity is a dangerous course of action. Hypermagnesemia can cause respiratory depression and cardiac arrest, so you need to assess for its development.

Clinical manifestations of moderate to severe hypokalemia include a. muscle spasms and rapid respirations. b. muscle weakness and cardiac dysrhythmias. c. confusion and irritability. d. vomiting and diarrhea.

ANS: B Hypokalemia causes muscle weakness (or paralysis) and cardiac dysrhythmias. Hypokalemia does not cause muscle spasms and rapid respirations or confusion and irritability. Vomiting and diarrhea can cause hypokalemia, but they are not signs and symptoms of it.

Causes of hypomagnesemia include a. hyperphosphatemia. b. chronic alcoholism. c. oliguric renal failure. d. clinical dehydration.

ANS: B Hypomagnesemia is common with chronic alcoholism. Hyperphosphatemia causes hypocalcemia. Oliguric renal failure and clinical dehydration reduce magnesium excretion.

The imbalance that occurs with oliguric renal failure is a. metabolic alkalosis. b. hyperkalemia. c. hypokalemia. d. hypophosphatemia.

ANS: B Oliguric renal failure decreases potassium excretion, which causes hyperkalemia. Oliguric renal failure decreases acid excretion and causes metabolic acidosis (not alkalosis). Oliguric renal failure does not cause hypokalemia or hypophosphatemia.

How is a patient hospitalized with a malignant tumor that secretes parathyroid hormone-related peptide monitored for the resulting electrolyte imbalance? a. Serum calcium, Chvostek and Trousseau signs b. Serum calcium, bowel function, level of consciousness c. Serum potassium, Chvostek and Trousseau signs d. Serum potassium, bowel function, level of consciousness

ANS: B Parathyroid hormone increases the plasma calcium concentration, and constipation and lethargy are manifestations of hypercalcemia. Parathyroid hormone increases the plasma calcium concentration, but these are signs of increased neuromuscular excitability, which occurs with hypocalcemia. Parathyroid hormone affects plasma concentration of calcium, not potassium.

The person at highest risk for developing hypernatremia is a person who a. self-administers a daily tap water enema to manage a partial bowel obstruction. b. receives tube feedings because he or she is comatose after a stroke. c. has ectopic production of ADH from small cell carcinoma of the lung. d. is receiving IV 0.9% NaCl at a fast rate.

ANS: B Tube feedings are associated with hypernatremia due to intake of highly concentrated solution that causes the kidneys to excrete extra water to remove the solute load. Absorption of excessive water from daily tap water enemas would cause hyponatremia. Uncontrolled secretion of ADH causes renal retention of water that leads to hyponatremia. An IV solution of 0.9% NaCl (normal saline) is isotonic.

A person who overuses magnesium-aluminum antacids for a long period of time is likely to develop a. hypokalemia. b. hyperkalemia. c. hypophosphatemia. d. hyperphosphatemia.

ANS: C Antacid overuse for a long time can cause hypophosphatemia by binding phosphate in the gastrointestinal tract and preventing its absorption. Magnesium-aluminum antacids do not cause hypokalemia, hyperkalemia, or hyperphosphatemia.

Total body water in older adults is a. increased due to decreased adipose tissue and decreased bone mass. b. increased due to decreased renal function and hormonal fluctuations. c. decreased due to increased adipose tissue and decreased muscle mass. d. decreased due to renal changes that cause diuresis with sodium excretion.

ANS: C Older adults have decreased total body water due to increased adipose tissue and decreased muscle mass. Older adults have increased adipose tissue. Hormonal fluctuations and diuresis with sodium excretion are not characteristic of older adults.

Abnormalities in intracellular regulation of enzyme activity and cellular production of ATP are associated with a. hyponatremia. b. hypocalcemia. c. hypophosphatemia. d. hypokalemia.

ANS: C Phosphate is an important component of ATP. Hypophosphatemia results in decreased ATP to cells. Hyponatremia, hypocalcemia, and hypokalemia do not affect ATP production.

11. A person who has hyperparathyroidism is likely to develop a. hypokalemia. b. hyperkalemia. c. hypocalcemia. d. hypercalcemia.

ANS: D A person who has hyperparathyroidism is likely to develop hypercalcemia, because parathyroid hormone causes calcium to come out of the bones and go to the ECF. Hypokalemia, hyperkalemia, and hypocalcemia are not the result of hyperparathyroidism.

Which change in a patient's assessment has the greatest urgency? a. Serum potassium concentration is decreasing; abdominal distention, but denies any difficulty breathing b. Serum calcium concentration is decreasing; reports constipation; is alert and denies any discomfort c. Serum calcium concentration is increasing; reports constipation; is alert and denies any discomfort d. Serum potassium concentration is increasing; has developed cardiac dysrhythmias, but denies any difficulty breathing

ANS: D Cardiac dysrhythmias from hyperkalemia need rapid attention to prevent potentially life-threatening consequences and are therefore the highest priority for reporting. Certainly you will want to report this symptomatic hypokalemia, but it is not your most urgent priority, because abdominal distention is not rapidly life threatening and you have another patient with cardiac dysrhythmias, which can be life threatening. Certainly you will want to report this hypocalcemia, but it is not your most urgent priority, because there are no signs and symptoms of hypocalcemia and you have another patient with cardiac dysrhythmias, which can be life threatening. Certainly you will want to report this symptomatic hypercalcemia, but it is not your most urgent priority, because constipation is not rapidly life threatening and you have another patient with cardiac dysrhythmias, which can be life threatening.

When a parent asks how they will know if their 2-month-old baby, who is throwing up and has frequent diarrhea, is dehydrated, the nurse's best response is a. "Clinical dehydration is the combination of extracellular fluid volume deficit and hypernatremia, so those are the diagnostic criteria." b. "If he doesn't wet his diaper all afternoon and his neck veins look flat when he is lying down, then he is probably dehydrated." c. "If he sleeps more than usual and acts tired when he is awake, then he is probably dehydrated." d. "If the soft spot on the top of his head feels sunken in and his mouth is dry between his cheek and his gums, then he is probably dehydrated."

ANS: D Checking whether the head feels sunken and the mouth is dry between check and gums are useful assessments of ECV deficit in an infant, which is an important part of clinical dehydration. It is true that clinical dehydration is the combination of extracellular fluid volume deficit and hypernatremia, but it does not address the question Mr. Worry is asking. Although the diaper information provides a useful assessment, neck veins are not a reliable assessment in an infant. Drowsiness and fatigue are not reliable assessments for dehydration.

How do clinical conditions that increase vascular permeability cause edema? a. Through altering the negative charge on the capillary basement membrane, which enables excessive fluid to accumulate in the interstitial compartment b. By causing movement of fluid from the vascular compartment into the intracellular compartment, which leads to cell swelling c. Through leakage of vascular fluid into the interstitial fluid, which increases interstitial fluid hydrostatic pressure d. By allowing plasma proteins to leak into the interstitial fluid, which draws in excess fluid by increasing the interstitial fluid osmotic pressure

ANS: D Clinical conditions that increase vascular permeability cause edema by allowing plasma proteins to leak into the interstitial fluid, which draws in excess fluid by increasing the interstitial fluid osmotic pressure. The capillary basement membrane does not change its charge with increased vascular permeability. Increased vascular permeability does not move water into the cells. Increasing the interstitial fluid osmotic pressure would not cause edema.

Osmoreceptors located in the hypothalamus control the release of a. angiotensin. b. atrial natriuretic peptide. c. aldosterone. d. vasopressin (antidiuretic hormone, ADH).

ANS: D Factors that increase secretion of ADH into the blood include increased osmolality of the blood, which is sensed by osmoreceptors in the hypothalamus. Release of angiotensin, atrial natriuretic peptide, and aldosterone is not controlled by osmoreceptors in the hypothalamus.

What is likely to lead to hyponatremia? a. Insufficient ADH secretion b. Excess aldosterone secretion c. Administration of intravenous normal saline d. Frequent nasogastric tube irrigation with water

ANS: D Sodium is lost from gastric secretions when nasogastric tubes are irrigated with water. The sodium diffuses into the irrigating water and is then lost when the aspirate is withdrawn. Excessive ADH would lead to hyponatremia by retention of water in the body, thus diluting the sodium. Excess aldosterone would increase serum sodium. Normal saline is an isotonic solution and will not alter the serum sodium.

What form of oral rehydration, bottled water or salty broth, is best suited for a patient who is demonstrating signs of clinical dehydration? a. Bottled water, because he is so weak that he might choke on the fluid when he swallows, and water would be less damaging to the lungs than salty soup b. Bottled water, because it will rehydrate his cells c. Salty soup, because he needs nutrition as well as fluid d. Salty soup, because it will provide some sodium to help hold the fluid in his blood vessels and interstitial fluid

ANS: D This man has indicators of clinical dehydration and he needs salt to hold the water in his extracellular compartment. Replacing fluids and electrolytes is more important than meeting his nutritional needs now.