Final answer:
The sign that should indicate dehydration in the client with fever and diarrhea is cool and clammy skin. Dehydration causes various symptoms including decreased urine output, dryness of skin, and physiological changes such as changes in blood components due to fluid loss.
Step-by-step explanation:
The client who has had a fever and diarrhea for the past three days is likely showing signs of dehydration. Among the choices provided, cool and clammy skin should indicate to the nurse that the client is dehydrated. Dehydration is associated with several symptoms and physiological changes, such as decrease in blood pressure, increase in pulse rate, dryness of skin, and delayed capillary refill time. While fever can increase insensible losses through skin evaporation and the lungs, diarrhea and vomiting can lead to significant water loss. Since chronic, watery diarrhea has been present, dehydration is likely to cause an increase in plasma protein concentration and chloride due to excessive water loss. Furthermore, the patient may exhibit signs such as decreased urine output, often referred to as oliguria, and a rise in body temperature due to reduced circulating fluid volume.