What finding might indicate dehydration in a child?

An increased hematocrit level can indicate dehydration in a child because it reflects a higher concentration of red blood cells in the blood relative to the plasma volume. When a child is dehydrated, the body loses fluids, leading to a decrease in plasma volume. As fluid volume decreases, the proportion of red blood cells (the hematocrit) increases. This hemoconcentration is a key indicator of dehydration and can be detected through a complete blood count.

While an increased heart rate may also be seen with dehydration, it is not as specific as hematocrit levels. Similarly, lower than normal hematocrit and less urination would not indicate dehydration; lower hematocrit could suggest overhydration or anemia, while decreased urination is a general sign of decreased fluid intake but may not necessarily correlate directly with the concentration of red blood cells. Thus, an elevated hematocrit provides a clearer indication of dehydration status in this context.