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Chapter 39. Electrolyte Disorders

What is the drug of choice for lithium-induced diabetes insipidus when lithium must be continued?

a. Amiloride

b. Desmopressin

c. Hydrochlorothiazide

d. Indomethacin

Answer a is correct. Amiloride closes sodium channels in the luminal membrane of the collecting tubule cells. This is the site where lithium enters cells and interferes with the actions of ADH.

Answer b is incorrect. Patient’s with nephrogenic diabetes insipidus have a defect in the vasopressin-2 receptor and have an impaired response to antidiuretic hormone (ADH). Desmopressin is generally not effective in nephrogenic diabetes insipidus, but may provoke a partial response at high doses.

Answer c is incorrect. Hydrochlorothiazide is useful in the treatment of other forms of nephrogenic diabetes insipidus.

Answer d is incorrect. Indomethacin is useful as adjunctive therapy in the treatment of other forms of nephrogenic diabetes insipidus.

Which medication is indicated for treatment of hyperkalemia? Select all that apply.

a. Lokelma

b. Sevelamer

c. Calcitonin

d. Furosemide

Answer a is correct. Lokelma (sodium zirconium cyclosilicate) is indicated for the management of hyperkalemia. It increases potassium excretion in the feces by binding potassium in the gastrointestinal (GI) tract. It exchanges potassium for hydrogen and sodium ions.

Answer d is correct. Furosemide is a loop diuretic that increases the renal excretion of potassium.

Answer b is incorrect. Sevelamer is a phosphate binder indicated for hyperphosphatemia. It binds dietary phosphate thus helping maintain phosphate levels in patients with renal dysfunction.

Answer c is incorrect. Calcitonin inhibits osteoclast activity in the bone, helping to promote renal excretion of calcium and phosphate.

Which of the following is true regarding administration of intravenous (IV) potassium chloride products? Select all that apply.

a. IV potassium should be given undiluted.

b. In most cases, IV potassium should not be given as an IV push.

c. Electrocardiographic (ECG) monitoring is recommended for IV potassium administration at a rate that exceeds 10 mEq/h.

d. IV potassium concentrations should be determined by the type of line available for administration (ie, peripheral vs central line).

Answers b, c, and d are correct. IV push doses of IV potassium should be avoided secondary to safety concerns ...

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