Which electrolyte abnormality is common with diuretic therapy and can cause confusion?

• A. Hyperkalemia.
• B. Hyponatremia.
• C. Hypocalcemia.
• D. Hypermagnesemia.

Answer: (B)

Hyponatremia is the electrolyte change most often seen with diuretic therapy and it can produce confusion. Diuretics promote loss of sodium in the urine, and thiazide diuretics, in particular, block sodium reabsorption in the distal tubule. This sodium loss combined with compensatory water retention driven by ADH lowers serum sodium and dilutes plasma sodium levels. The resulting low serum osmolality allows water to shift into brain cells, causing cerebral edema and neurologic symptoms such as confusion, along with possible dizziness or lethargy. Older adults are especially at risk, so monitoring mental status and sodium levels is important when patients are on diuretics. Other electrolyte abnormalities can occur with diuretics (like hypocalcemia with loop diuretics or changes in potassium), but they don’t typically present with confusion as directly as hyponatremia does.