Geriatric patients, newborns, and infants are especially prone to hyperthermia because they:

• A. exhibit poor thermoregulation
• B. sweat excessively
• C. have higher metabolic rates
• D. are more physically active

Answer: (A)

The main idea is how well the body can regulate temperature by balancing heat production and heat loss. Newborns and infants have immature control of body temperature, with thin skin, a large surface area relative to body mass, and still-developing or less effective sweat glands. This combination makes it hard for them to dissipate heat quickly. Similarly, older adults often have reduced sweating, diminished blood vessel responses, and sometimes dehydration, all of which blunt heat loss. Because these groups can’t shed heat efficiently, they’re more susceptible to hyperthermia when exposed to heat or fever. The other options don’t fit because these populations typically don’t sweat excessively, don’t necessarily have higher metabolic rates, and aren’t defined by higher activity levels.