In a dehydrated patient, which combination of urine specific gravity and PCV is most likely?

In a dehydrated patient, which combination of urine specific gravity and PCV is most likely?

• A. High urine SG and high PCV
• B. High urine SG and low PCV
• C. Low urine SG and high PCV
• D. Low urine SG and low PCV

Answer: (A)

Dehydration concentrates both urine and the blood. When a patient loses fluid, plasma volume shrinks, so the PCV (hematocrit) rises because the same number of red blood cells occupies less plasma (hemoconcentration). At the same time, the kidneys conserve water in an attempt to restore fluid balance, producing a smaller volume of urine that is more concentrated, which raises the urine specific gravity. Therefore, the pattern most consistent with dehydration is high urine specific gravity alongside a high PCV.

Dehydration concentrates both urine and the blood. When a patient loses fluid, plasma volume shrinks, so the PCV (hematocrit) rises because the same number of red blood cells occupies less plasma (hemoconcentration). At the same time, the kidneys conserve water in an attempt to restore fluid balance, producing a smaller volume of urine that is more concentrated, which raises the urine specific gravity. Therefore, the pattern most consistent with dehydration is high urine specific gravity alongside a high PCV.