Which urine characteristic is typical in SIADH?

Which urine characteristic is typical in SIADH?

• A. High urine volume with low osmolality
• B. Low urine osmolality
• C. High urine osmolality
• D. High pH

Answer: (C)

In SIADH, too much antidiuretic hormone causes the kidneys to reabsorb water instead of excreting it. This dilutes the blood, leading to hyponatremia and low serum osmolality, while the urine becomes concentrated because water is being kept in the body. The result is a high urine osmolality as the urine is more concentrated than normal. Urine volume may be normal or reduced because the body is holding onto water, and urine pH isn’t specifically altered by SIADH. So the typical urine finding is a high urine osmolality.

In SIADH, too much antidiuretic hormone causes the kidneys to reabsorb water instead of excreting it. This dilutes the blood, leading to hyponatremia and low serum osmolality, while the urine becomes concentrated because water is being kept in the body. The result is a high urine osmolality as the urine is more concentrated than normal. Urine volume may be normal or reduced because the body is holding onto water, and urine pH isn’t specifically altered by SIADH.

So the typical urine finding is a high urine osmolality.