A 45-year-old man on lithium for a bipolar disorder developed congestive heart failure 2 weeks ago. He now presents with drowsiness, nausea, vomiting, blurred vision and coarse tremors.
Which of the following concurrent medications, if taken in combination with lithium, would be most likely to cause these symptoms?
A . Acetazolamide
B . Furosemide
C . Hydrochlorothiazide
D . Spironolactone
Answer: C
Explanation:
Hydrochlorothiazide Approximately 95% of a single dose of lithium is eliminated in the urine. The drug is handled by the kidneys in the same manner as sodium, ie most of the filtered lithium is reabsorbed in the proximal tubule. Hence loading with sodium will increase lithium excretion, while sodium depletion will promote the retention of lithium. All diuretics decrease renal lithium clearance.
However, thiazide diuretics cause the greatest retention of lithium amongst all diuretics.