An anterior fontanelle can be used to gauge hydration status in infants.

• A. An anterior fontanelle can be used to gauge hydration status.
• B. Fontanelle cannot indicate hydration.
• C. Fontanelle changes color with hydration.
• D. Fontanelle is unrelated to hydration.

Answer: (A)

In infants, the anterior fontanelle is a useful quick clue to hydration because it reflects intravascular volume status. The fontanelle remains open for the first year or so, and when an infant is dehydrated, reduced intracranial volume from fluid loss can cause the fontanelle to become sunken or depressed. A sunken fontanelle suggests significant dehydration, especially when seen with other signs like dry mucous membranes, decreased tears, and reduced urine output. A fontanelle that is bulging or tense, on the other hand, points to increased intracranial pressure rather than dehydration. In a well-hydrated infant, the fontanelle is typically flat or only mildly depressed at rest. So, observing the anterior fontanelle provides a practical, noninvasive cue to hydration status, but it should be considered along with other signs of hydration and perfusion rather than used in isolation.