Exam 3- Renal Flashcards
Question 1: What percentage of total body water (TBW) is typically water content?
A. 30%
B. 50%
C. 60%
D. 70%
Answer: C. 60%
Rationale: The slide indicates that approximately 60% of total body water is water, and this can vary with gender, age, and body fat percentage.
Which hormone primarily regulates osmolar homeostasis by causing the kidneys to reabsorb water?
A. Atrial Natriuretic Peptide (ANP)
B. Renin
C. Antidiuretic Hormone (ADH)
D. Aldosterone
Answer: C. Antidiuretic Hormone (ADH)
Rationale: According to the slide, the pituitary release of Vasopressin, also known as Antidiuretic Hormone, is stimulated by osmolality-sensors in the anterior hypothalamus to regulate osmolar homeostasis by increasing water reabsorption in the kidneys.
Question 3: What is the role of Atrial Natriuretic Peptide (ANP) in fluid/volume homeostasis? (Select all that apply)
A. Promotes sodium and water reabsorption
B. Reduces blood volume and blood pressure
C. Dilates blood vessels
D. Increases sympathetic nervous system activity
Answers: B. Reduces blood volume and blood pressure, C. Dilates blood vessels
Rationale: Atrial Natriuretic Peptide works by promoting sodium and water excretion in the kidneys, which reduces blood volume and blood pressure. It also dilates blood vessels and inhibits renin and aldosterone secretion, leading to lowered vascular resistance and increased urine production. It does not increase sympathetic nervous system activity; it decreases it.
What triggers the Renin-Angiotensinogen-Aldosterone System (RAAS) to cause sodium and water reabsorption?
A. Increased volume sensed by the juxtaglomerular apparatus
B. Decreased volume sensed by the juxtaglomerular apparatus
C. Increased osmolarity sensed by the osmolality-sensors
D. Decreased osmolarity sensed by the osmolality-sensors
Answer: B. Decreased volume sensed by the juxtaglomerular apparatus
Rationale: The slide specifies that the juxtaglomerular apparatus senses changes in volume, and a decrease in volume at the juxtaglomerular apparatus triggers the Renin-Angiotensinogen-Aldosterone System, which results in sodium and water reabsorption to maintain volume homeostasis.
The correct answer is “B. Decreased volume sensed by the juxtaglomerular apparatus,” which aligns with the mechanisms described across the sources. Reduced renal perfusion pressure, which can be interpreted as a decreased volume status, and a lower sodium chloride concentration at the macula densa both stimulate renin release, ultimately triggering the RAAS. This system plays a crucial role in the regulation of blood volume and systemic blood pressure by adjusting kidney function.
What is considered the normal range for serum sodium concentration?
A. 125-135 mEq/L
B. 135-145 mEq/L
C. 145-155 mEq/L
D. 155-165 mEq/L
Answer: B. 135-145 mEq/L
Rationale: The slide indicates that the normal serum sodium concentration range is between 135-145 mEq/L.
At which serum sodium concentration levels should elective surgery be corrected prior to proceeding?
A. ≤125 or ≥145 mEq/L
B. ≤125 or ≥155 mEq/L
C. ≤130 or ≥150 mEq/L
D. ≤135 or ≥145 mEq/L
Answer: B. ≤125 or ≥155 mEq/L
Rationale: The slide specifies that serum sodium concentrations of ≤125 mEq/L or ≥155 mEq/L are the cutoff ranges at which correction should be sought prior to an elective surgical case due to concerns about acute changes.
Which of the following conditions is associated with euvolemic hyponatremia? (Select all that apply)
A. Diuretic excess
B. Hypothyroidism
C. Nephrotic syndrome
D. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
Answers: B. Hypothyroidism, D. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
Rationale: The slide presents euvolemic hyponatremia as being related to conditions where there is normal volume status but an imbalance in solute and water, citing endocrine-related issues such as hypothyroidism and SIADH as underlying causes. SIADH is specifically characterized by excessive retention of water with dilutional hyponatremia.
In the context of hyponatremia, what does an elevated endogenous vasopressin level indicate?
A. Decreased water reabsorption
B. Over-resuscitation with fluids
C. Excessive sodium loss
D. Reduced catecholamine release
Answer: B. Over-resuscitation with fluids
Rationale: The slide mentions that one cause of hyponatremia can be over fluid-resuscitation, which is related to an increased endogenous vasopressin level leading to increased water reabsorption. Elevated vasopressin levels enhance the reabsorption of water in the kidneys, which can dilute sodium in the body, causing hyponatremia.
which clinical findings are indicative of hypovolemic hyponatremia?
A. Decreased skin turgor and orthostatic hypotension
B. Peripheral edema and rales
C. Muscle cramps and lethargy
D. Nausea and headache
Answer: A. Decreased skin turgor and orthostatic hypotension
Rationale: The slide’s algorithm suggests that clinical signs of hypovolemic hyponatremia include physical examination findings such as decreased skin turgor, dry mucous membranes, orthostatic hypotension, tachycardia, and oliguria.
In the setting of euvolemic hyponatremia, what laboratory findings would you expect with regard to urine sodium concentration?
A. Urine sodium (U_Na) > 20 mEq/L
B. Urine sodium (U_Na) < 20 mEq/L
C. Urine sodium (U_Na) variable
D. Urine sodium (U_Na) not relevant
Answer: A. Urine sodium (U_Na) > 20 mEq/L
Rationale: The diagnostic algorithm points out that in cases of euvolemic hyponatremia, such as with Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), the urine sodium concentration is typically greater than 20 mEq/L, reflecting the kidney’s excretion of sodium while retaining water.
When evaluating a patient with hypervolemic hyponatremia, which of the following would NOT be an expected underlying cause according to the diagnostic algorithm?
A. Acute renal failure
B. Diuretic excess
C. Nephrotic syndrome
D. Cardiac failure
Answer: B. Diuretic excess
Rationale: The flowchart indicates that hypervolemic hyponatremia is commonly associated with conditions that cause fluid overload, such as acute renal failure, chronic renal failure, nephrotic syndrome, cardiac failure, and cirrhosis. Diuretic excess is typically associated with hypovolemic hyponatremia, as it leads to sodium and water loss.
Which of the following symptoms are commonly associated with mild hyponatremia (serum sodium 130-135 mEq/L)- select all?
A. Headache
B. Seizures
C. Muscle cramps
D. Respiratory arrest
Answer: A. Headache and C. Muscle cramps
Rationale: The slide indicates that mild hyponatremia with serum sodium levels ranging from 130 to 135 mEq/L can present with symptoms such as headache, nausea, vomiting, fatigue, confusion, muscle cramps, and depressed reflexes. Seizures and respiratory arrest are not typically associated with mild hyponatremia but with more severe cases.
At what serum sodium level do the most severe consequences of hyponatremia, such as seizures, coma, and death, generally occur?
A. 120-130 mEq/L
B. Less than 120 mEq/L
C. 130-135 mEq/L
D. More than 135 mEq/L
Answer: B. Less than 120 mEq/L
Rationale: According to the slide, the most severe neurological consequences of hyponatremia, including seizures, coma, and death, typically occur when serum sodium levels drop below 120 mEq/L.
Which symptom is shared between the clinical presentations of mild and moderate hyponatremia- select all?
A. Headache
B. Muscle cramps
C. Lethargy
D. Confusion
Answer: A. Headache and D. Confusion and C. Lethargy/malaise
Rationale: Both mild (serum sodium 130-135 mEq/L) and moderate (serum sodium 120-130 mEq/L) hyponatremia can present with headache and confusion. These symptoms appear to worsen as the severity of the hyponatremia increases.
What is the maximum recommended rate of sodium correction in the treatment of hyponatremia to prevent osmotic demyelination syndrome?
A. 0.5 mEq/L/hr
B. 1.0 mEq/L/hr
C. 1.5 mEq/L/hr
D. 2.0 mEq/L/hr
Answer: C. 1.5 mEq/L/hr
Rationale: The slide states that sodium correction should not exceed 1.5 mEq/L/hr when treating hyponatremia to avoid rapid increases which can lead to osmotic demyelination syndrome, a condition that can cause permanent neurological damage.
In the event of hyponatremic seizures, what is the initial treatment approach?
A. Administration of hypertonic saline at 3-5 ml/kg over 20 minutes
B. Rapid infusion of normal saline
C. Administration of electrolyte drinks
D. Continuous infusion of diuretics
Answer: A. Administration of hypertonic saline at 3-5 ml/kg over 20 minutes
Rationale: The slide outlines that hyponatremic seizures are a medical emergency and should be treated with 3-5 ml/kg of 3% hypertonic saline over 20 minutes to quickly raise serum sodium levels and control the seizures. It is important to treat cautiously to avoid complications associated with rapid sodium correction.
During the treatment of hyponatremia, how often should sodium levels be checked?
A. Every 2 hours
B. Every 4 hours
C. Every 6 hours
D. Once daily
Answer: B. Every 4 hours
Rationale: The instruction on the slide to “Check Na+ level q 4 hr while replacing” suggests that serum sodium levels should be monitored every 4 hours during the replacement therapy to safely manage the correction rate and avoid complications from too rapid an increase in sodium concentration.
Which patient population is at a higher risk for developing hypernatremia due to poor oral intake?
A. Adolescents and young adults
B. Middle-aged adults
C. Very young and very old individuals
D. Individuals with enhanced physical activity
Answer: C. Very young and very old individuals
Rationale: The slide indicates that very young and very old individuals, especially those with altered mental status, are at higher risk for hypernatremia due to poor oral intake, which may lead to dehydration and increased serum sodium concentration.
What is a potential endocrine cause of hypernatremia?
A. Hyperthyroidism
B. Hypothyroidism
C. Addison’s disease
D. Diabetes insipidus
Answer: D. Diabetes insipidus
Rationale: Diabetes insipidus is listed as a common cause of hypernatremia. This condition is characterized by the loss of dilute urine due to the body’s inability to concentrate urine, which can lead to an increased concentration of sodium in the blood.
Which iatrogenic action can lead to hypernatremia, select all?
A. Administration of Bicarb
B. Use of nonsteroidal anti-inflammatory drugs (NSAIDs)
C. Overcorrection of hyponatremia
D. Use of antibiotic medications
Answer: C. Overcorrection of hyponatremia & A. Excessive sodium bicarb (treating acidosis)
Rationale: The slide identifies overcorrection of hyponatremia as a common cause of hypernatremia. This can occur when the sodium levels in a hyponatremic patient are increased too rapidly, leading to an abnormally high sodium concentration in the blood.
What are the clinical findings associated with hypovolemic hypernatremia?
A. Peripheral edema and ascites
B. Decreased skin turgor and orthostatic hypotension
C. Central diabetes insipidus and gestational diabetes insipidus
D. Hyperaldosteronism and Cushing’s syndrome
Answer: B. Decreased skin turgor and orthostatic hypotension
Rationale: The slide lists clinical findings associated with hypovolemic hypernatremia, such as decreased skin turgor, flat neck veins, dry mucous membranes, orthostatic hypotension, tachycardia, and oliguria. These symptoms suggest a deficit in total body water with a relative excess of sodium.
Which conditions can cause euvolemic hypernatremia according to the diagnostic algorithm?
A. Inadequate sodium intake and intravenous sodium bicarbonate administration
B. Renal salt and water loss and gastrointestinal losses
C. Central diabetes insipidus and insensible losses
D. Saltwater drowning and hypertonic saline enemas
Answer: C. Central diabetes insipidus and insensible losses
Rationale: Euvolemic hypernatremia occurs when there is a loss of water without a significant change in sodium level, which is illustrated in the slide by conditions such as central diabetes insipidus and insensible losses through the respiratory tract or skin.
For a patient presenting with hypervolemic hypernatremia, which of the following is a likely cause?
A. Excessive administration of diuretics
B. Profound glycosuria
C. Excessive sodium intake through intravenous therapy
D. Sweating and diarrhea
Answer: C. Excessive sodium intake through intravenous therapy
Rationale: Hypervolemic hypernatremia is described on the slide as being associated with conditions that cause an increase in sodium, such as excessive sodium intake through intravenous therapy, hyperaldosteronism, and Cushing’s syndrome.
What is the recommended rate of sodium reduction in the treatment of hypernatremia to prevent neurological complications?
A. 0.5 mEq/L/hr and no more than 10 mEq/L per day
B. 1 mEq/L/hr and no more than 12 mEq/L per day
C. 1.5 mEq/L/hr and no more than 15 mEq/L per day
D. 2 mEq/L/hr and no more than 20 mEq/L per day
Answer: A. 0.5 mEq/L/hr and no more than 10 mEq/L per day
Rationale: The slide specifies that the sodium reduction rate should not exceed 0.5 mEq/L/hr, and the total daily decrease should not surpass 10 mEq/L to avoid complications such as cerebral edema, seizures, and neurologic damage.
Which treatment is appropriate for a patient with euvolemic hypernatremia?
A. Administration of normal saline
B. Administration of diuretics
C. Water replacement orally or with D5W (5% dextrose in water)
D. Restriction of fluid intake
Answer: C. Water replacement orally or with D5W (5% dextrose in water)
Rationale: The slide indicates that the treatment for euvolemic hypernatremia is water replacement, which can be done orally or with intravenous fluids such as 5% dextrose in water (D5W). This approach helps to correct the water deficit without significantly affecting the sodium level.
What are the severe symptoms of hypernatremia that may indicate a medical emergency?
A. Orthostasis and restlessness
B. Tremor and muscle twitching
C. Seizures and death
D. Spasticity and lethargy
Answer: C. Seizures and death
Rationale: The slide lists seizures and death among the severe symptoms of hypernatremia, highlighting the urgency of medical intervention when these symptoms are present due to the risk of severe neurological outcomes.
What is the normal serum potassium range that is considered safe for proceeding with surgery?
A. 2.5-4.0 mmol/L
B. 3.0-4.5 mmol/L
C. 3.5-5.0 mmol/L
D. 4.0-5.5 mmol/L
Answer: C. 3.5-5.0 mmol/L
Rationale: The slide indicates that the normal potassium level is between 3.5-5.0 mmol/L. This range is typically considered safe for surgery as it reflects a normal balance of potassium, which is a critical electrolyte for cellular function, especially in heart muscle cells
What role does aldosterone play in potassium regulation?
A. It decreases potassium secretion and sodium reabsorption.
B. It increases potassium secretion and decreases sodium reabsorption.
C. It decreases both potassium secretion and sodium reabsorption.
D. It increases potassium secretion and increases sodium reabsorption.
Answer: D. It increases potassium secretion and increases sodium reabsorption.
Rationale: According to the slide, aldosterone causes the distal nephron to secrete potassium and reabsorb sodium. This hormonal regulation helps maintain potassium balance in the body and is part of the renin-angiotensin-aldosterone system.
In patients with renal failure, how is potassium excretion affected?
A. Potassium excretion increases, leading to hypokalemia.
B. Potassium excretion is unaffected.
C. Potassium excretion declines, shifting more burden to the gastrointestinal system.
D. Potassium excretion increases through the respiratory system.
Answer: C. Potassium excretion declines, shifting more burden to the gastrointestinal system.
Rationale: The slide explains that in renal failure, potassium excretion declines because the kidneys are less able to excrete potassium. To compensate, the body shifts more potassium excretion to the gastrointestinal system. This adjustment is important because potassium accumulation can have serious cardiac effects.
When evaluating a patient for surgery, a CRNA notes the patient’s medication includes a drug that affects aldosterone. How would this impact potassium regulation in the body?
A. Decrease potassium excretion, risking hyperkalemia
B. Increase potassium excretion, potentially leading to hypokalemia
C. Have no effect on potassium levels
D. Increase potassium retention, risking hyperkalemia
Answer: B. Increase potassium excretion, potentially leading to hypokalemia
Rationale: Aldosterone promotes potassium excretion and sodium retention. A medication affecting aldosterone could therefore increase potassium excretion, and a CRNA would need to be vigilant for signs of hypokalemia, which could have significant perioperative implications.
Select all that apply. Which conditions are known causes of hypokalemia due to increased renal potassium loss?
A. Use of thiazide diuretics
B. High-dose glucocorticoids therapy
C. Hyperaldosteronism
D. High dietary intake of potassium
Answer: A, B, C
Rationale: Thiazide diuretics, loop diuretics, high-dose glucocorticoids, and hyperaldosteronism are mentioned on the slide as causes of hypokalemia due to increased renal potassium loss. High dietary intake of potassium is not listed as a cause of renal potassium loss.
What medical treatment is associated with hypokalemia due to the consumption of natural products?
A. Licorice
B. Cranberry juice
C. Echinacea
D. St. John’s Wort
Answer: A. Licorice
Rationale: The slide specifically mentions that excessive licorice consumption can lead to hypokalemia, likely due to the presence of glycyrrhizin, which can mimic aldosterone and cause increased potassium excretion.
What treatment options are recommended for patients with hypokalemia- select all?
A. Intravenous potassium supplementation
B. Oral potassium supplementation
C. Potassium-sparing diuretics
D. Dietary potassium intake
Answer: B. Oral potassium supplementation, C. Potassium-sparing diuretics, D. Dietary potassium intake
Rationale: Oral potassium chloride is often the treatment of choice, especially for patients who are not critically low in potassium and can safely ingest and absorb oral medications. In patients with low-normal or mild hypokalemia, increasing dietary potassium is also appropriate, especially for those with hypertension or heart disease. Potassium-sparing diuretics can be used to address ongoing diuretic-induced potassium loss or in certain cases of hyperaldosteronism. In severe cases, intravenous potassium may be necessary, especially when there are significant ECG changes, symptoms of severe hypokalemia, or if the patient cannot tolerate oral potassium (Cleveland Clinic, AAFP, GGC Medicines).
What ECG change is commonly associated with hypokalemia?
A. ST-segment elevation
B. P-wave enlargement
C. U wave
D. QRS widening
Answer: C. U wave
Rationale: The presence of U waves on an ECG is a sign that may be observed in hypokalemia, which indicates a potassium imbalance affecting cardiac electrical activity.
For a patient with hypokalemia, which route of potassium administration is generally preferred when both options are feasible?
A. Intravenous (IV)
B. Oral (PO)
C. Subcutaneous
D. Intramuscular
Answer: B. Oral (PO)
Rationale: Oral administration is usually preferred for potassium replacement as it works effectively and is associated with fewer risks compared to intravenous administration. However, if a patient’s condition is severe or they cannot tolerate oral administration, IV potassium may be necessary.
What is the maximum rate of intravenous potassium replacement usually recommended to avoid complications such as arrhythmias?
A. 5-10 mmol/L/hr
B. 10-20 mmol/L/hr
C. 20-40 mmol/L/hr
D. 40-60 mmol/L/hr
Answer: B. 10-20 mmol/L/hr
Rationale: The slide suggests that when intravenous potassium replacement is necessary, it’s generally done at a controlled rate of 10-20 mEq/L/hr to avoid rapid changes that could lead to complications.
Select all that apply. Which factors can cause a shift of potassium into cells, leading to hypokalemia?
A. Beta-agonists
B. Insulin
C. Bicarbonate
D. Diuretics
Answer: A, B, C
Rationale: Beta-agonists, insulin, and bicarbonate are known to drive potassium into cells, which can reduce the amount of potassium in the extracellular fluid and potentially exacerbate hypokalemia. Diuretics typically cause hypokalemia by increasing renal excretion of potassium, not by shifting it into cells.
Hyperventilation can as well.
What ECG changes are indicative of severe hyperkalemia?
A. Peaked T waves
B. P wave disappearance
C. Sine wave pattern
D. All of the above
Answer: D. All of the above
Rationale: Severe hyperkalemia can be indicated on an ECG by a progression of changes starting with peaked T waves, followed by the disappearance of P waves, prolongation of the QRS complex, and potentially leading to a sine wave pattern, which is a pre-terminal rhythm, indicating an urgent need for medical intervention.
Which medications or conditions should be carefully managed or monitored due to their potential to increase serum potassium levels? (Select all that apply)
A. Drugs that inhibit the renin-angiotensin-aldosterone system (RAAS)
B. Depolarizing neuromuscular blockers like succinylcholine
C. Drugs that promote potassium excretion
D. Hypoaldosteronism
Answer: A, B, D
Rationale: Drugs that inhibit RAAS or potassium excretion can lead to increased serum potassium levels. Succinylcholine is known to increase serum potassium acutely, especially in certain patient populations. Hypoaldosteronism can also result in increased potassium levels due to decreased excretion.
What populations are at a higher risk of developing hyperkalemia with the use of succinylcholine?
A. Patients with chronic kidney disease (CKD)
B. Diabetic patients
C. Women
D. A and B only
Answer: D. A and B only
Rationale: Patients with conditions that affect potassium homeostasis, such as those with chronic kidney disease, are at higher risk of hyperkalemia with the use of succinylcholine. Diabetic patients can also be at increased risk due to potential baseline kidney damage and altered insulin levels, which affect cellular potassium shifts.
What is the initial treatment for hyperkalemia to stabilize the cell membrane?
A. Dialysis
B. Administration of Calcium
C. Administration of Insulin with Glucose
D. Hyperventilation to increase pH
Answer: B. Administration of Calcium
Rationale: Calcium is often used as the first line of treatment for hyperkalemia to stabilize the cardiac cell membrane, especially when ECG changes are present or if the patient is symptomatic.
What treatment can be used to shift potassium into cells, thus temporarily lowering serum potassium levels?
A. Bicarbonate
B. Insulin with Glucose
C. Loop Diuretics
D. Both A and B
Answer: D. Both A and B
Rationale: Both bicarbonate and insulin with glucose can cause a shift of potassium into cells (works in 10-20 min). Insulin facilitates the uptake of glucose into cells, which also drives potassium inside, and bicarbonate can correct acidosis, which can help shift potassium into cells as well.
also Hyperventilation - > quick drastic change.
Hyperventilation (↑pH by 0.1 →↓K+ by 0.4-1.5 mmol/L)
Why should succinylcholine be avoided in the treatment of patients with hyperkalemia?
A. It can cause hypertension.
B. It may further increase serum potassium levels.
C. It reduces the effectiveness of insulin and glucose.
D. It leads to hyperventilation.
Answer: B. It may further increase serum potassium levels.
Rationale: Succinylcholine, a depolarizing neuromuscular blocking agent, can cause an acute rise in serum potassium levels, which can be dangerous in the setting of hyperkalemia.
What is the normal range for ionized calcium in the blood?
A. 0.8-1.0 mmol/L
B. 1.2-1.38 mmol/L
C. 1.5-1.8 mmol/L
D. 2.0-2.5 mmol/L
Answer: B. 1.2-1.38 mmol/L
Rationale: The slide states that the normal range for ionized calcium (iCa++) is 1.2-1.38 mmol/L. Ionized calcium is the physiologically active form of calcium in the blood.
How does blood pH affect ionized calcium levels?
A. An increase in pH leads to increased binding of calcium to albumin, decreasing ionized calcium.
B. A decrease in pH leads to increased binding of calcium to albumin, decreasing ionized calcium.
C. An increase in pH leads to decreased binding of calcium to albumin, increasing ionized calcium.
D. A decrease in pH leads to decreased binding of calcium to albumin, increasing ionized calcium.
Answer: A
Rationale: Alkalosis, or an increase in blood pH, causes more calcium to bind to albumin, which reduces the level of ionized (free) calcium in the blood. Conversely, acidosis, or a decrease in blood pH, causes less calcium to bind to albumin, which increases the level of ionized calcium.
Which hormone decreases blood calcium levels by inhibiting bone resorption and renal reabsorption of calcium?
A. Parathyroid hormone (PTH)
B. Vitamin D
C. Calcitonin
D. Growth hormone
Answer: C. Calcitonin
Rationale: Calcitonin lowers blood calcium levels primarily by inhibiting osteoclasts, the cells that break down bone and release calcium into the bloodstream, and by reducing renal reabsorption of calcium
what is a common complication after thyroid or parathyroid surgery that can lead to hypocalcemia?
A. Hyperparathyroid hormone secretion
B. Decreased parathyroid hormone secretion
C. Increased calcitonin secretion
D. Hypercalcemia
Answer: B. Decreased parathyroid hormone secretion
Rationale: Decreased secretion of parathyroid hormone (PTH) is a known complication post-thyroid or parathyroid surgery and can result in hypocalcemia, as PTH is crucial for the regulation of blood calcium levels.
What are the primary actions of parathyroid hormone (PTH) in calcium regulation? (Select all that apply)
A. Increases gastrointestinal absorption of calcium
B. Increases renal excretion of calcium
C. Increases bone resorption
D. Increases renal reabsorption of calcium
Answer: A, C, D
Rationale: PTH raises blood calcium levels by increasing calcium absorption in the gastrointestinal tract, promoting calcium reabsorption in the kidneys, and stimulating the release of calcium from bones
Why is magnesium important in the context of calcium balance in the body?
A. It directly increases calcium absorption in the gut.
B. It is required for the production of parathyroid hormone.
C. It binds calcium and increases blood calcium levels.
D. It inhibits the action of vitamin D.
Answer: B. It is required for the production of parathyroid hormone.
Rationale: Magnesium is essential for the proper function of the parathyroid glands and for the production of PTH, which in turn is crucial for maintaining calcium balance.
After how many units of packed red blood cells (PRBCs) transfusion should ionized calcium (iCa++) be checked due to the risk of hypocalcemia?
A. After 1-2 units
B. After 2-3 units
C. After 3-4 units
D. After 4+ units
Answer: D. After 4+ units
Rationale: Citrate, which is used as a preservative in blood products, binds calcium and can lead to hypocalcemia, especially after transfusion of multiple units of blood. It is advisable to check ionized calcium levels after 4 or more units of PRBCs have been transfused to prevent and treat potential hypocalcemia.
What serum calcium level is generally indicative of hyperparathyroidism?
A. >9 mg/dL
B. >11 mg/dL
C. >13 mg/dL
D. >15 mg/dL
Answer: B. >11 mg/dL
Rationale: The slide indicates that a serum calcium level greater than 11 mg/dL is typically associated with hyperparathyroidism, a condition where the parathyroid glands secrete too much parathyroid hormone, leading to elevated levels of calcium in the blood.
Which condition is characterized by excessively high calcium levels due to malignancy?
A. Hyperparathyroidism
B. Hypoparathyroidism
C. Serum Ca++ > 13
D. Vitamin D deficiency
Answer: C. Cancer-associated hypercalcemia
Rationale: The slide points out that a serum calcium level greater than 13 mg/dL is often seen in cancer, suggesting cancer-associated hypercalcemia, which occurs when cancer leads to the breakdown of bone tissue or the production of parathyroid hormone-related protein.
Which of the following is a less common cause of hypercalcemia? (Select all that apply)
A. Vitamin D intoxication
B. Milk-alkali syndrome
C. Granulomatous diseases like sarcoidosis
D. Hypoaldosteronism
Answer: A, B, C
Rationale: The slide lists vitamin D intoxication, milk-alkali syndrome (excessive gastrointestinal calcium absorption), and granulomatous diseases such as sarcoidosis as less common causes of hypercalcemia. Hypoaldosteronism is not mentioned as a cause of hypercalcemia on this slide.
Which symptom is commonly associated with hypocalcemia?
A. Hypertension
B. Paresthesias
C. Confusion
D. Seizures
Answer: D. seizures
What electrocardiogram (ECG) change is indicative of hypocalcemia?
A. Short QT interval
B. Prolonged QT interval
C. Short PR interval
D. Elevated ST segment
Answer: B. Prolonged QT interval
Rationale: A prolonged QT interval can occur in hypocalcemia, reflecting changes in cardiac muscle excitability.
What life-threatening complication should be carefully monitored for after parathyroidectomy?
A. Hypercalcemia
B. Laryngospasm
C. Myocardial depression
D. Hypertension
Answer: B. Laryngospasm
Rationale: Post-parathyroidectomy hypocalcemia can induce laryngospasm, a critical complication requiring immediate attention and management.
What cardiac dysrhythmia is commonly associated with hypomagnesemia?
A. Atrial fibrillation
B. Bradycardia
C. Polymorphic ventricular tachycardia, specifically Torsades de Pointes
D. Sinus tachycardia
Answer: C. Polymorphic ventricular tachycardia, specifically Torsades de Pointes
Rationale: Hypomagnesemia can lead to several types of ventricular dysrhythmias, among which Torsades de Pointes is particularly associated with low magnesium levels.
What is a primary cause of hypomagnesemia?
A. Excessive dietary intake of magnesium
B. Renal wasting
C. Hyperparathyroidism
D. Use of calcium channel blockers
Answer: B. Renal wasting
Rationale: Renal wasting, a condition where the kidneys excrete too much magnesium, is a common cause of hypomagnesemia.
