Which of the following medications is associated with the greatest risk of electrolyte disturbances?

Hydrochlorothiazide is a thiazide diuretic commonly used to treat high blood pressure and fluid retention. One of the main actions of this medication is to increase the excretion of sodium, chloride, and water through the kidneys. This diuretic effect can lead to significant electrolyte imbalances, particularly hypokalemia (low potassium levels) and hyponatremia (low sodium levels). Patients on hydrochlorothiazide are often monitored for these disturbances because they can lead to serious complications if not addressed.

In contrast, the other medications listed do not have the same direct impact on electrolyte balance. Ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), primarily affects renal function and inflammation but does not directly cause significant electrolyte disturbances. Metformin, used for managing type 2 diabetes, can lead to lactic acidosis in rare cases but does not typically result in electrolyte imbalances. Levothyroxine, a thyroid hormone replacement, is important for managing thyroid levels but is not known to significantly affect electrolyte balance either.

Thus, hydrochlorothiazide stands out as the medication associated with the greatest risk of electrolyte disturbances among the choices provided.