How do loop diuretics affect calcium levels in the body?

Loop diuretics, such as furosemide and bumetanide, primarily act on the ascending loop of Henle in the kidneys, where they inhibit the sodium-potassium-chloride co-transporter. This action leads to increased excretion of sodium, chloride, and water, resulting in diuresis. Importantly, loop diuretics also affect calcium handling in the body.

By inhibiting the reabsorption of sodium and chloride in the loop of Henle, loop diuretics indirectly lead to increased calcium excretion in the urine. The mechanism involves a reduction in the electrochemical gradient that drives the reabsorption of calcium in that segment of the nephron. Consequently, the loss of this reabsorptive capacity can result in lower serum calcium levels, hence the potential for hypocalcemia in patients taking these medications.

This relationship underscores the importance of monitoring electrolyte levels in patients who are prescribed loop diuretics, as they can affect not only fluid status but also the balance of electrolytes, including calcium.