In SIADH, which finding is typical?

In SIADH, which finding is typical?

• A. Fluid retention/edema
• B. Dehydration
• C. Orthostatic hypotension
• D. Polyphagia

Answer: (A)

In SIADH the key idea is how excess ADH changes sodium and fluid balance. ADH drives water retention, which dilutes serum sodium and lowers serum osmolality. Yet the body compensates by wasting sodium in the urine, so the effective circulating volume stays near normal. The result is a euvolemic state with hyponatremia and a concentrated urine that is inappropriately rich in water (urine osmolality higher than serum and urine sodium often elevated). Clinically, you don’t expect edema or dehydration—edema isn’t typical of SIADH because the volume status is effectively normal, maintained by natriuresis. Orthostatic hypotension and polyphagia aren’t features here.

In SIADH the key idea is how excess ADH changes sodium and fluid balance. ADH drives water retention, which dilutes serum sodium and lowers serum osmolality. Yet the body compensates by wasting sodium in the urine, so the effective circulating volume stays near normal. The result is a euvolemic state with hyponatremia and a concentrated urine that is inappropriately rich in water (urine osmolality higher than serum and urine sodium often elevated). Clinically, you don’t expect edema or dehydration—edema isn’t typical of SIADH because the volume status is effectively normal, maintained by natriuresis. Orthostatic hypotension and polyphagia aren’t features here.