Which statement about thiazide-induced hypercalcemia is true?

Which statement about thiazide-induced hypercalcemia is true?

• A. Decreases renal calcium reabsorption
• B. Increases intestinal calcium absorption only
• C. Increases renal calcium reabsorption
• D. Suppresses PTH secretion

Answer: (C)

Thiazide diuretics raise serum calcium by increasing calcium reabsorption in the distal tubule of the kidney. They block the Na-Cl cotransporter in this segment, which reduces sodium reuptake and creates conditions that promote calcium reabsorption back into the bloodstream. The result is less calcium lost in urine (hypocalciuria) and a modest rise in blood calcium, leading to hypercalcemia. They don’t primarily boost intestinal calcium absorption, and while a higher calcium level can suppress PTH, that isn’t the mechanism driving the effect. So the statement that it increases renal calcium reabsorption best explains thiazide-induced hypercalcemia.

Thiazide diuretics raise serum calcium by increasing calcium reabsorption in the distal tubule of the kidney. They block the Na-Cl cotransporter in this segment, which reduces sodium reuptake and creates conditions that promote calcium reabsorption back into the bloodstream. The result is less calcium lost in urine (hypocalciuria) and a modest rise in blood calcium, leading to hypercalcemia. They don’t primarily boost intestinal calcium absorption, and while a higher calcium level can suppress PTH, that isn’t the mechanism driving the effect. So the statement that it increases renal calcium reabsorption best explains thiazide-induced hypercalcemia.