Which lab change is associated with fluid volume deficit?

Study for the MCC Block 2 Test. Enhance your skills with interactive quizzes featuring hints and explanations. Prepare effectively and excel in your exam!

Multiple Choice

Which lab change is associated with fluid volume deficit?

When the body loses fluid volume, blood becomes more concentrated and renal perfusion drops. The kidneys respond by conserving water, which can lead to prerenal azotemia—waste products begin to build up in the blood. Both BUN and creatinine rise, but BUN tends to increase more because more urea is reabsorbed in the kidneys when water is being conserved. That’s why the lab pattern you’d expect in fluid volume deficit is increased BUN and creatinine. The other patterns don’t fit: decreased BUN and creatinine would imply better or excessive dilution, not dehydration; decreased serum osmolality would suggest overhydration; and decreased hematocrit would imply dilution from fluid overload rather than volume loss (in dehydration, hematocrit often rises due to hemoconcentration).

When the body loses fluid volume, blood becomes more concentrated and renal perfusion drops. The kidneys respond by conserving water, which can lead to prerenal azotemia—waste products begin to build up in the blood. Both BUN and creatinine rise, but BUN tends to increase more because more urea is reabsorbed in the kidneys when water is being conserved. That’s why the lab pattern you’d expect in fluid volume deficit is increased BUN and creatinine.

The other patterns don’t fit: decreased BUN and creatinine would imply better or excessive dilution, not dehydration; decreased serum osmolality would suggest overhydration; and decreased hematocrit would imply dilution from fluid overload rather than volume loss (in dehydration, hematocrit often rises due to hemoconcentration).

More practice questions