Quote from johari
i would go with the oral mucous membranes:
rationale: dehydration exhibits in addition to loss of skin tugor, longitudinal tongue furrows, sunken eyes, dry mucus membranes, upper body muscle weakness, speech difficulty and confusion.
i'm chosing oral mucous membranes assessment because skin tugor is different in different age groups. elderly vs. younger people etc... just my two cents.
though k+ is elevated in hypotonic dehydration (sodium loss > water loss) there isn't enough information in the question. what is the right answer?
i did a search on "signs of dehydration" and came across this: http://www.saferchild.org/dehydrat.htm
mild dehydration: (increase fluid intake -- and for babies, call a medical professional): thirst, dry lips, dry mouth, flushed skin, fatigue, irritability, headache, urine begins to darken in color, urine output decreases
moderate dehydration: (call a medical professional): all of the signs of mild dehydration, plus: skin doesn't bounce back quickly when pressed, very dry mouth, sunken eyes, (in infant - sunken fontanel, the soft spot on the head), output of urine will be limited and color of urine will be dark yellow, cramps, stiff and/or painful joints, severe irritability, fatigue, severe headache
severe dehydration: (call emergency number): all of the signs of mild and moderate dehydration, plus: blue lips, blotchy skin, confusion, lethargy, cold hands and feet, rapid breathing, rapid and weak pulse, low blood pressure, dizziness, fainting, high fever, inability to pee or cry tears, disinterest in drinking fluid.
so my guess is that you should pick the first sign of dehydration, which, according to this source, would be mucous membranes