Which condition is most associated with excessive water retention due to antidiuretic hormone activity?

Which condition is most associated with excessive water retention due to antidiuretic hormone activity?

• A. SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion).
• B. Hyperaldosteronism
• C. Dehydration
• D. Diabetes Insipidus

Answer: (A)

When antidiuretic hormone activity is excessive, the kidneys reabsorb more water than normal, increasing total body water without a corresponding rise in sodium. This dilutes the blood sodium (hyponatremia) and lowers serum osmolality. In SIADH, ADH is secreted inappropriately even when the body doesn’t need to conserve water, so you get continued water retention, euvolemia or mild hypervolemia, and concentrated urine with low serum sodium. Hyperaldosteronism mainly causes sodium retention (and thus some water retention) through aldosterone’s effect on the distal nephron, not because of excessive ADH. Dehydration triggers ADH release to conserve water, but that’s an appropriate response to water loss, not a condition of excessive ADH activity. Diabetes insipidus involves insufficient ADH action or kidney insensitivity, leading to excessive water loss, not retention. So, the condition most linked to excessive water retention driven by ADH is SIADH.

When antidiuretic hormone activity is excessive, the kidneys reabsorb more water than normal, increasing total body water without a corresponding rise in sodium. This dilutes the blood sodium (hyponatremia) and lowers serum osmolality. In SIADH, ADH is secreted inappropriately even when the body doesn’t need to conserve water, so you get continued water retention, euvolemia or mild hypervolemia, and concentrated urine with low serum sodium.

Hyperaldosteronism mainly causes sodium retention (and thus some water retention) through aldosterone’s effect on the distal nephron, not because of excessive ADH. Dehydration triggers ADH release to conserve water, but that’s an appropriate response to water loss, not a condition of excessive ADH activity. Diabetes insipidus involves insufficient ADH action or kidney insensitivity, leading to excessive water loss, not retention.

So, the condition most linked to excessive water retention driven by ADH is SIADH.