In dehydration, urine specific gravity tends to be:

In dehydration, urine specific gravity tends to be:

• A. Decreased
• B. Isosthenuric
• C. Isotonic
• D. Increased

Answer: (D)

When a patient is dehydrated, the body tries to conserve water, so the kidneys produce more concentrated urine. Urine specific gravity measures how concentrated the urine is—the higher the number, the more solutes relative to water. The rise in ADH (vasopressin) during dehydration causes the kidneys to reabsorb more water in the collecting ducts, producing urine that is more concentrated. That’s why urine specific gravity tends to be increased in dehydration. If urine were isosthenuric, its SG would be close to that of plasma, indicating the kidneys aren’t concentrating urine—unlike what happens with dehydration. Isotonic refers to a solution having the same osmolality as plasma, which doesn’t describe urine concentration in dehydration. So the increased SG best reflects the concentrated urine produced to conserve water.

When a patient is dehydrated, the body tries to conserve water, so the kidneys produce more concentrated urine. Urine specific gravity measures how concentrated the urine is—the higher the number, the more solutes relative to water. The rise in ADH (vasopressin) during dehydration causes the kidneys to reabsorb more water in the collecting ducts, producing urine that is more concentrated. That’s why urine specific gravity tends to be increased in dehydration. If urine were isosthenuric, its SG would be close to that of plasma, indicating the kidneys aren’t concentrating urine—unlike what happens with dehydration. Isotonic refers to a solution having the same osmolality as plasma, which doesn’t describe urine concentration in dehydration. So the increased SG best reflects the concentrated urine produced to conserve water.