In SIADH, which of the following best reflects signs of fluid volume overload?

• A. Weight gain without edema, hypertension, tachycardia
• B. Weight gain with edema, hypertension, tachycardia
• C. Weight loss and dehydration
• D. No weight change

Answer: (A)

In SIADH, too much antidiuretic hormone causes the body to retain free water, increasing total body water without a corresponding rise in salt. This often leads to a subtle fluid shift that shows up as weight gain, but because the salt balance isn’t strongly increased, edema isn’t typically present. So the best description of fluid volume changes here is weight gain from water retention without edema, with possible mild signs like hypertension or tachycardia reflecting the body’s response to the altered volume status. Weight loss would indicate dehydration, and no weight change would mean no fluid retention; edema would point to more overt hypervolemia, which is less characteristic of SIADH.