Which of the following indicates dehydration in an infant?

• A. Rapid weight gain without edema
• B. Increased skin turgor and full fontanel
• C. Moist mucous membranes with warm skin
• D. Poor skin turgor and sunken fontanel; dry mucous membranes

Answer: (D)

In infants, dehydration presents as a deficit in body fluids that shows up in several physical signs. Poor skin turgor means the skin stays tented after being gently lifted, reflecting decreased interstitial fluid. A sunken fontanelle indicates reduced intracranial and overall fluid volume. Dry mucous membranes show lack of moisture in the oral cavity, and decreased tearing can also occur. When these signs appear together—poor skin turgor, a sunken fontanel, and dry mucous membranes—they point to dehydration.

The other options describe hydration or fluid overload rather than deficit: rapid weight gain without edema suggests excess fluid; increased skin turgor with a full fontanel implies good hydration or even overhydration; moist mucous membranes with warm skin indicate adequate fluid status.