Currently, there is no effective tool available to measure hydration status and distinguish those at risk. The reliability and validity of current hydration assessment methods and criteria such as thirst, skin turgor, blood pressure, pulse, urine output and specific gravity, MRI, dilution methods and bioimpedance, is limited, and the methods are inaccurate or expensive. HM could be used to monitor patients with a wide variety of clinical conditions resulting in changes in individuals hydration level, including alterations in body fluids pre- and post-surgery, digestion problems, blood pressure, muscle cramps, and obesity. Dehydration is a frequent cause of morbidity and mortality in the elderly. Another important application of MHM is in neonatology since dehydration is a leading cause of infant morbidity and mortality worldwide. In the United States, dehydration, secondary to gastroenteritis, accounts for 10% of hospital admissions. The tissue hydration monitor developed by Artann [8, 9] may enable the identification and monitoring of hydration status and may have a significant long-term impact on the morbidity and mortality of at-risk population.
Again, it is not practical for use during exercise due to the need of a urine sample. Although portable skin hydration monitors exist, such devices are designed for use in dermatology as a measure for skin moisture. Skin hydration monitors measure moisture levels in the corneocytes (dead skin cells) in the stratum corneum, the outer layers of the skin. In terms of body water, a normal moisture level in the stratum corneum could either be the result of, firstly, body euhydration or, secondly, sweating whilst in a dehydrated state. It therefore follows that skin hydration levels do not reflect body hydration. It is also not possible to determine the level and quantity of sweat, since the water in the stratum corneum reaches a maximum when the body is in a state of euhydration. Therefore it would not be possible to determine any excess sweat that evaporates or drips off the skin.
In a preferred embodiment of the present invention, a portable monitor is arranged to measure core body temperature non-invasively. Hydration is monitored in real-time device and measurements are output via a display to the user. In this manner, a user can see his or her hydration status during exercise. Through this, it is intended that dehydration is avoided and thus performance maximised.