A nurse is reinforcing teaching about sibling adaptation with a parent of a child who has cystic fibrosis. Which of the following instructions should the nurse include in the teaching?

Choice A rationale:
Urine osmolality 500 mOsm/kg. Urine osmolality is a measure of urine concentration and is not a reliable indicator of infection. It reflects the kidney's ability to concentrate urine and can vary based on hydration status and other factors. An elevated urine osmolality could suggest dehydration, not necessarily infection.
Choice B rationale:
WBC 17,500/mm3. This is the correct choice. An elevated white blood cell count (WBC) is a hallmark sign of infection. The body's immune response to an infection often includes an increase in WBC count, particularly the neutrophil count. This elevation is known as leukocytosis and is a red flag for infection.
Choice C rationale:
BUN 12 mg/dL. Blood Urea Nitrogen (BUN) measures kidney function and hydration status. While an elevated BUN can indicate dehydration, it is not a specific marker for infection. BUN levels can be influenced by various factors, including diet and renal function.
Choice D rationale:
Urine specific gravity 1.014. Urine-specific gravity reflects the concentration of solutes in urine and the kidney's ability to concentrate or dilute urine. While changes in urine specific gravity can indicate dehydration or overhydration, it is not a direct indicator of infection. An infection is better detected through changes in WBC count and other clinical signs.

Choice A rationale:
Hct 45% (Choice A) refers to the hematocrit level, which measures the proportion of blood volume occupied by red blood cells. While dehydration can lead to elevated hematocrit due to hemoconcentration, a hematocrit value of 45% is within the normal range for both males and females. Dehydration might cause a mild increase, but more significant elevations would be expected in cases of severe dehydration.
Choice B rationale:
Urine specific gravity 1.035 (Choice B) is an indicator of concentrated urine, which is a characteristic finding in dehydration. Dehydration reduces the body's water content, leading to more concentrated urine with higher specific gravity values. A normal range for urine-specific gravity is typically between 1.005 and 1.030.
Choice C rationale:
Capillary refill of less than 2 seconds (Choice C) is not a finding consistent with dehydration. Capillary refill time measures the time it takes for color to return to the nailbed after pressure is applied. Prolonged capillary refill time might indicate poor peripheral perfusion, which can be a sign of dehydration, but a refill time of less than 2 seconds is considered within the normal range.
Choice D rationale:
A urine output of 35 ml/hr (Choice D) is not indicative of dehydration. In fact, a urine output of 35 ml/hr is relatively normal and suggests adequate fluid intake and hydration. Dehydration would typically result in reduced urine output as the body conserves water.