A client with ulcerative colitis presents with severe dehydration. What is the best indicator that this client has an actual fluid deficit?

• A. Stool count of 10 episodes of diarrhea in 24 hours
• B. Weight gain of 2 kg and 1000 mL output
• C. Admission weight 74.3 kg and 2 days later 72 kg
• D. Daily intake of 2400 mL and output of 1600 mL plus diarrheal stools

Answer: (C)

The key idea is that actual fluid deficit shows up as a loss of body weight over a short period. When you’re dehydrated, the body’s total water decreases, and weight changes reflect that net loss. In this scenario, the client’s weight drops from 74.3 kg to 72 kg over two days—a loss of 2.3 kg, which is about 2.3 liters of fluid. That direct change in weight is a concrete, quantitative indicator of how much fluid the body has lost.

Stool frequency or volume alone doesn’t tell you how much fluid has been lost overall, because some losses may be offset by intake or rehydration, and some fluid losses occur through insensible routes you can’t measure easily. Similarly, a balance between intake and output can mask an ongoing deficit if losses aren’t fully accounted for or if intake isn’t matching those losses. So the weight decrease provides the clearest, integrated measure of dehydration.