Pediatric ATI Practice Exam

What laboratory value would indicate that treatment for severe dehydration in an infant is effective?

1. Potassium 2.9 mEq/L

2. Sodium 140

3. Urine specific gravity 1.035

4. BUN 25 mg

The correct answer is: Sodium 140

The laboratory value indicating that treatment for severe dehydration in an infant is effective is sodium at 140 mEq/L. This level is within the normal range for sodium, which typically falls between 135 and 145 mEq/L. When an infant is severely dehydrated, electrolyte levels, including sodium, can become imbalanced. A sodium of 140 mEq/L suggests that the dehydration is responding positively to treatment, indicating proper hydration and a return to normal electrolyte homeostasis. Other values, such as potassium levels, urine specific gravity, and blood urea nitrogen (BUN), may not reflect adequate rehydration. A potassium level of 2.9 mEq/L indicates hypokalemia, which is a concern that needs to be addressed, rather than a sign of effective treatment. A urine specific gravity of 1.035 suggests concentrated urine commonly associated with dehydration, rather than a resolution, as effective treatment would typically lower the specific gravity. A BUN of 25 mg could indicate possible dehydration or renal impairment; ideal treatment would show improvement in this value as well. Thus, among the options provided, a sodium level of 140 mEq/L serves as the best indicator of effective treatment for severe dehydration in an infant.