Clinical signs of dehydration are first observed with what percent of total body water loss?

• A. 3%
• B. 5%
• C. 7%
• D. 10%

Answer: (B)

Clinical signs of dehydration become evident when about five percent of total body water is lost. At this level, the body's fluid-regulation systems can no longer compensate fully, so you see noticeable changes such as thirst, a dry mouth, dry mucous membranes, and reduced skin turgor, often with a faster heart rate. Smaller losses may provoke thirst but not clear signs, while more substantial losses—around seven to ten percent—lead to more serious effects like fatigue, dizziness, reduced urine output, and confusion.