ELECTROLYTE QUIZ

A 35 year-old man with bipolar disorder treated on lithium, is referred to you for chronic polyuria and polydipsia. He complains that he has to void once every hour.

Laboratory studies:

Serum sodium                     146 mEq/L

Blood urea nitrogen               35 mg/dL

Serum creatinine                    1.9 mg/dL

Serum osmolality                 305 mOsm/kg

24-hr urine volume                  5 L

Urine sodium                         28 mEq/L

Urine osmolality                   190 mOsm/kg

Which of the following might be appropriate in the management of this patient?

(A)      Discontinue lithium

(B)      Demeclocycline

(C)      Vasopressin V2 receptor antagonist

(D)      Fluid restriction

(E)      Furosemide