Which medication can be used to decrease renal response to ADH in SIADH?

Which medication can be used to decrease renal response to ADH in SIADH?

• A. Loop diuretics
• B. Vasopressin receptor antagonists
• C. Thiazide diuretics
• D. Steroids

Answer: (B)

In SIADH, there’s too much ADH, so the kidneys keep reabsorbing water and dilute the blood, leading to hyponatremia. The medication that directly reduces the kidney’s response to ADH is a vasopressin receptor antagonist. By blocking the V2 receptors in the collecting ducts, it prevents ADH from acting, so the kidneys excrete free water rather than solutes. This aquaresis raises serum sodium gradually and helps correct the hyponatremia without large losses of electrolytes. Other diuretics don’t specifically block ADH’s action: loop and thiazide diuretics remove water and electrolytes through different mechanisms and aren’t targeted to the ADH pathway, while steroids don’t address the ADH-driven water retention seen in SIADH.

In SIADH, there’s too much ADH, so the kidneys keep reabsorbing water and dilute the blood, leading to hyponatremia. The medication that directly reduces the kidney’s response to ADH is a vasopressin receptor antagonist. By blocking the V2 receptors in the collecting ducts, it prevents ADH from acting, so the kidneys excrete free water rather than solutes. This aquaresis raises serum sodium gradually and helps correct the hyponatremia without large losses of electrolytes.

Other diuretics don’t specifically block ADH’s action: loop and thiazide diuretics remove water and electrolytes through different mechanisms and aren’t targeted to the ADH pathway, while steroids don’t address the ADH-driven water retention seen in SIADH.