In the oliguric phase, which lab finding is true?

In the oliguric phase, which lab finding is true?

• A. GFR is normal
• B. BUN and Creatinine decrease
• C. Urine specific gravity concentrated
• D. Fluid volume decreases

Answer: (C)

During the oliguric phase, the kidneys fail to produce much urine, but they still tend to conserve water. That means the small amount of urine that is formed becomes highly concentrated, so the urine specific gravity is elevated. This reflects continued water reabsorption in the tubules under ADH influence, yielding a high-osmolality urine despite low volume. In contrast, GFR is not normal—it drops, which is why waste products like BUN and creatinine rise rather than fall. Fluid volume also tends to increase because the kidneys aren’t excreting as much fluid, leading to retention and possible edema.

During the oliguric phase, the kidneys fail to produce much urine, but they still tend to conserve water. That means the small amount of urine that is formed becomes highly concentrated, so the urine specific gravity is elevated. This reflects continued water reabsorption in the tubules under ADH influence, yielding a high-osmolality urine despite low volume.

In contrast, GFR is not normal—it drops, which is why waste products like BUN and creatinine rise rather than fall. Fluid volume also tends to increase because the kidneys aren’t excreting as much fluid, leading to retention and possible edema.