Dehydration, depending on the severity, sometimes creates only small telltale signs while having a big effect on the body, especially in the elderly.
Dehydration occurs when a person loses more water than they take in. It takes an adequate amount of fluid for the body to function properly; for example, to regulate body temperature through sweating, maintain blood pressure, and eliminate bodily waste. If severe enough, dehydration can lead to confusion, weakness, urinary tract infections, pneumonia, bedsores in bed-ridden patients, or even death. In general, a human can survive for only about four days without any fluids.
Elderly dehydration is especially common for a number of reasons: some medications, such as for high blood pressure or anti-depressants, are diuretic; some medications may cause patients to sweat more; a person’s sense of thirst becomes less acute as they age; frail seniors have a harder time getting up to get a drink when they’re thirsty, or they rely on caregivers who can’t sense that they need fluids; and as we age our bodies lose kidney function and are less able to conserve fluid (this is progressive from around the age of 50, but becomes more acute and noticeable over the age of 70). Illness, especially one that causes vomiting and/or diarrhea, also can cause elderly dehydration.