Review Question - QID 210764

A 32-year-old man presents with excessive urination. He reports that he urinates 10 times a day and wakes up multiple times a night to pee. He complains that this is affecting both his social life and his ability to concentrate at work. He states that he always has an “active bladder,” but his symptoms worsened when he started meeting with a physical trainer last month who told him he should increase his water intake to prevent dehydration. The patient has a history of migraines and bipolar 1 disorder. His medications include metoprolol, lithium, and naproxen as needed. A basic metabolic panel is performed, and the results are shown below:

Serum:
Na+: 149 mEq/L
Cl-: 102 mEq/L
K+: 3.4 mEq/L
HCO3-: 26 mEq/L
Urea nitrogen: 12 mg/dL
Creatinine: 1.0 mg/dL
Glucose: 78 mg/dL
Ca2+: 9.5 mg/dL

A urinalysis is obtained, which reveals pale-colored urine with a specific gravity of 0.852 and a urine osmolarity of 135 mOsm/L. The patient undergoes a water deprivation test. The patient’s urine specific gravity increases to 0.897 and urine osmolarity is now 155 mOsm/L. The patient is given an antidiuretic hormone analog. Urine osmolarity rises to 188 mOsm/L. Which of the following is the most appropriate initial management for the patient’s condition?