Professional and Linguistic Assessments Board (PLAB) Practice Exam

What is a common side effect of long-term use of thiazide diuretics?

1. Hypokalemia

2. Hypercalcemia

3. Hypomagnesemia

4. All of the above

The correct answer is: All of the above

Long-term use of thiazide diuretics can lead to several electrolyte imbalances in the body. Each of the potential side effects listed is associated with the pharmacological action of thiazide diuretics, which primarily work by inhibiting sodium reabsorption in the distal convoluted tubule of the nephron, leading to increased urine output and altered electrolyte levels. Hypokalemia, or low potassium levels, is a common consequence of thiazide diuretic therapy. Since thiazides can increase potassium excretion in urine, patients may experience significant potassium depletion, which can lead to muscle weakness, cramps, and arrhythmias if left unaddressed. Hypercalcemia, or elevated calcium levels in the blood, is also a noted side effect of thiazide diuretics. Thiazides can enhance calcium reabsorption in the renal tubules, which often results in increased serum calcium levels. This effect can be beneficial in patients with calcium nephrolithiasis, but in others, it may pose risks such as kidney stones or hyperparathyroidism. Hypomagnesemia, the deficiency of magnesium in the body, can occur with the long-term administration of thiazide diuretics as well. These medications can