Which condition is associated with high urine specific gravity due to concentrated urine?

Which condition is associated with high urine specific gravity due to concentrated urine?

• A. SIADH
• B. Diabetes Insipidus
• C. Renal Failure
• D. Hyperglycemia

Answer: (A)

Concentrated urine with a high urine specific gravity happens when the kidneys reclaim water under the influence of antidiuretic hormone. In SIADH, ADH is released inappropriately, so even though the body may be waterlogged and serum osmolality is low, the collecting ducts keep reabsorbing water. That makes the urine more concentrated, raising urine osmolality and specific gravity. The other scenarios don’t produce this pattern: diabetes insipidus lacks ADH action, so the urine is dilute with low specific gravity; renal failure often impairs the kidney’s ability to concentrate urine, leading to lighter, not concentrated, urine; hyperglycemia causes osmotic diuresis, which also tends to dilute urine as glucose pulls water into the urine.

Concentrated urine with a high urine specific gravity happens when the kidneys reclaim water under the influence of antidiuretic hormone. In SIADH, ADH is released inappropriately, so even though the body may be waterlogged and serum osmolality is low, the collecting ducts keep reabsorbing water. That makes the urine more concentrated, raising urine osmolality and specific gravity. The other scenarios don’t produce this pattern: diabetes insipidus lacks ADH action, so the urine is dilute with low specific gravity; renal failure often impairs the kidney’s ability to concentrate urine, leading to lighter, not concentrated, urine; hyperglycemia causes osmotic diuresis, which also tends to dilute urine as glucose pulls water into the urine.