What adverse effect is associated with hydrochlorothiazide (HCTZ)?

Hydrochlorothiazide (HCTZ) is a thiazide diuretic commonly used for managing hypertension and edema. One of the notable adverse effects associated with HCTZ is hyponatremia, which is a lower-than-normal concentration of sodium in the blood. Thiazide diuretics act on the distal convoluted tubule of the nephron to promote diuresis by inhibiting the sodium-chloride co-transporter. This mechanism leads to increased sodium and water excretion; however, it can also result in a decrease in serum sodium levels, especially in scenarios where there is excessive fluid loss or in elderly patients who may be more susceptible to electrolyte imbalances.

The adverse effect of hyponatremia can have significant clinical implications, such as causing neurological symptoms ranging from mild confusion to seizures in severe cases. Monitoring electrolyte levels, particularly sodium, is essential in patients receiving HCTZ to prevent these complications.

In contrast, hydrochlorothiazide is associated with hypokalemia rather than hyperkalemia, may not typically cause hyperphosphatemia, and, in fact, tends to decrease calcium excretion—potentially leading to hypercalcemia in some patients. Understanding these effects is crucial for managing