Disorders of Sodium and Water Homeostasis Practice Questions

A 76 year old woman (65 kg, 170 cm) has been hospitalized for a few days. Her laboratory results this morning reveal a serum sodium of 110 mEq/L. What is this patient's sodium deficit (note: use 120 mEq/L as the desired safe serum sodium concentration)?

A. 278 mEq

B. 293 mEq

C. 732 mEq

D. 878 mEq

B.

Which of the following is the appropriate initial treatment for a patient with nephrogenic DI?

A. Amiloride

B. Furosemide

C. Enteral water

D. 0.9% NaCl

C.

An adult patient was initiated on bumetanide approx. 1 week ago. During a follow-up appointment, she is noted to be confused, lethargic, and weak. Vital signs are taken and she is found to be hypotensive, tachycardic, and orthostatic. Laboratory studies are sent, and the serum sodium is reported as 159 mEq/L. Which of the following is the most appropriate initial IV fluid to administer to this patient?

A. 0.9% NaCl

B. Dextrose 5% in water

C. 3% NaCl

D. 0.45% NaCl

A.

An adult patient with T1DM is admitted with a serum glucose concentration of 990 mg/dL (54.9 mmol/L) and a serum sodium concentration of 124 mEq/L. What is the best estimate of the patient's serum sodium concentration corrected for hyperglycemia?

A. 109 mEq/L

B. 132 mEq/L

C. 139 mEq/L

D. 154 mEq/L

C.

An adult patient is admitted with a severe metabolic acidosis secondary to diarrhea. The patient is administered sodium bicarbonate to correct the acidosis. Excessive sodium bicarbonate administration could result in which of the following sodium disorders?

A. Hypovolemic hypernatremia

B. Euvolemic hypernatremia

C. Hypervolemia hypernatremia

D. Hypervolemia hyponatremia

C.

What are the usual determinants of serum osmolality?

A. Serum sodium, glucose, and blood urea nitrogen concentrations

B. Serum sodium, potassium, and glucose concentrations

C. Serum potassium, bicarbonate, and glucose concentrations

D. Serum sodium, bicarbonate, and blood urea nitrogen concentrations

A.

A 75 year old woman (60 kg) is hospitalized after suffering a stroke. Her serum sodium concentration has been trending downward since admission (baseline 137 mEq/L ; third day 121 mEq/L). Upon physical exam, she has good skin turgor, no lower extremity edema, and appears hydrated. The medical team is considering the syndrome of inappropriate secretion of antidiuretic hormone or cerebral wasting syndrome among their differential diagnoses. Which of the following is most helpful in differentiating between these two diagnoses?

A. Serum sodium concentration

B. Serum osmolality

C. Serum antidiuretic hormone concentration

D. Urine sodium concentration

D.

The medical intern asks your assistance in developing a treatment plan for a patient with severe hyponatremia who is seizing. The serum sodium concentration is 110 mEq/L, which is felt to be an acute change from baseline based on laboratory values from the previous day. An order is placed for an initial dose of 3% NaCl. Which sodium concentration below represents the maximum sodium increase recommended in the first one hour of treatment in this setting?

A. 111 mEq/L (mmol/L)

B. 113 mEq/L (mmol/L)

C. 115 mEq/L (mmol/L)

D. 120 mEq/L (mmol/L)

C.

A 48 year old woman with a history of HFrEF presents to clinic for routine follow up. She has increased lower extremity edema and has experienced an 8-lb weight gain over the previous 2 weeks. She reports no dietary indiscretions and is adherent to her guideline-directed medical therapy. Her serum creatinine is at baseline (1.1 mg/dL). She is taking furosemide 120 mg TID at home. Which of the following is the most appropriate outpatient intervention?

A. Continue the current furosemide dose

B. Increase furosemide to 240 mg TID for the next 2 days

C. Initiate metolazone 5 mg before the first furosemide dose each morning

D. Initiate furosemide 40 mg IV every 4 hours

C.

A 24 year old construction worker (70 kg) experiences a syncopal episode on the roof of a new apartment building on a hot summer day. He presents to the ED with a BP of 76/30 mmHg, HR of 138 bpm, and significant orthostasis. His serum sodium is 164 mEq/L. Which of the following is the most appropriate initial intervention?

A. A 500 mL IV bolus of D5W over 30 minutes

B. A 750 mL bolus of oral rehydration solution ingested over 4 hours

C. A 1000 mL IV bolus of 0.9% NaCl over 30 minutes

D. A 1000 mL IV bolus of D5W/0.45% NaCl over 30 minutes

C.

Spironolactone reaches its site of action in the cortical collecting duct via which of the following processes?

A. Diffusion from the systemic circulation

B. Active secretion by proximal tubular cells

C. Glomerular filtration by proximal tubular cells

D. Reabsorption by proximal tubular cells

A.

Which of the following is the most appropriate maintenance fluid for adults to avoid the occurrence of iatrogenic hypernatremia?

A. D5W/0.45% NaCl with 20 mEq KCl/L

B. D5W/0.2% NaCl with 20 mEq KCl/L

C. D5W/0.9% NaCl with 20 mEq KCl/L

D. Lactated Ringer's solution

A.

A 26 year old who takes lithium 1200 mg daily presents to clinic with a serum sodium concentration fo 145 mEq/L and complaints of excessive urination over the previous few days. The patient's psychiatrist recommends continuing the lithium due to the patient's treatment-resistant bipolar disorder. Which of the following is the most appropriate recommendation for this patient?

A. Indomethacin 50 mg BID

B. Amiloride 5 mg QD

C. Sodium restriction to 4000 mg NaCl per day

D. Demeclocycline 300 mg TID

B.

How will the administration of 1,800 mL of D5W/0.45% NaCl change the extracellular fluid (ECF) and intracellular fluid (ICF) compartment volumes?

A. Increase the ECF by 1,800 mL

B. Increase the ECF and ICF by 900 mL each

C. Increase the ECF by 1,200 mL and the ICF by 600 mL

D. Increase the ECF by 1,500 mL and the ICF by 300 mL

C.

A 32 year old pregnant woman is admitted to the hospital with nausea and disorientation. She is diagnosed with syndrome of inappropriate secretion of antidiuretic hormone. The patient's serum sodium has decreased from 130 mEq/L to 118 mEq/L, and she is becoming increasingly confused and somnolent. The patient has a history of anaphylaxis when receiving a sulfa-containing medication. Which of the following is the most appropriate treatment to initiate in this patient?

A. Demeclocycline 300 mg TID

B. Dietary sodium restriction to 2000 mg/day

C. Furosemide 40 mg BID

D. Tolvaptan 15 mg QD

D.