Water – the key component in our body

There is a considerable difference in the amount of water held, depending on the tissue in question. Whereas muscles comprise almost 80% of water, bones are made up of roughly 20% water, and fatty tissue varies between 10% and 40%. Ultimately, it is the individual make-up of the body which determines the amount of water in a human body.

Consequently, a person with a large amount of muscle mass has a higher percentage of water in their body than somebody with a lot of fatty tissue. In the same way, the physiological make-up between men and women results in different amounts of muscle mass and fatty tissue, which is the reason why men have a higher percentage of TBW in relation to their body weight. However, it is not only the build and age of a person which has an effect on the amount of water in the body, age is also a key factor. As a person gets older, muscle mass continually declines and is increasingly replaced by fatty and connective tissue. Consequently, the amount of total body water in a person over 85 drops to a level of around 45%.

Water is the body's most important solvent and enables numerous substances to be transported around the body. It plays a key role in metabolism and tissue stability. Furthermore, it is indispensable for thermoregulation. Owing to its important role, the body regulates its water balance within narrow limits, since even the loss of only a few per cent of the normal TBW results in an impairment of physical and mental performance. If the body continues to lose water, this has an adverse effect on the circulatory system and all organs do not function properly. Consequently, a person needs to consume water on a regular basis, and can only survive for a matter of a few days without it.

The amount of water in the body can also be adversely affected by pathological conditions, which makes it a good indicator of how healthy or ill a person is. 

If the body loses more water than it consumes, dehydration is the result, which can lead to life-threatening desiccation. This is particularly the case in older people as they are less susceptible to feeling thirsty, and the water reserves and the ability of the kidneys to concentrate urine and thus retain water in the body decrease. They run the risk of “dehydrating” unnoticed, especially during hot summer months. Besides drinking insufficient quantities of liquids, increased loss of water can also cause critical conditions due to high temperatures, fever or diarrhoea. Dehydration becomes noticeable in older people after a short time by means of behavioural abnormalities and states of confusion, and is a frequent reason for hospitalisation.

However, insufficient water is not the only cause of some illnesses; too much water can also have an adverse effect on bodily functions. 

If passing water is impaired by kidney dysfunction, water retention and storage may also be the result. Indeed, oedemata is not only a threat with renal insufficiency, it is also one of the symptoms of pronounced heart failure. Depending on the side of the heart concerned, blood accumulates in the pulmonary vessels or in the veins of the legs. Water escapes from the vessels as a result of increased pressure and manifests itself in the form of a pulmonary or leg oedema.

Assessing the state of hydration is an important part of everyday routines in hospitals. A physical examination, weight checks or imaging and laboratory chemical procedures can determine the hydration level. Nevertheless, if there is any doubt, these methods are too imprecise or invasive and time-consuming.

A quick, precise and non-invasive alternative is seca mBCA. Using bioimpedance analysis, the amount of TBW and percentage of ECW can be determined.

This user-friendly and patient-friendly method is particularly beneficial for old people and dialysis patients, where a regular check of the hydration level is critical. Changes in the patient’s hydration level can be recognised and treated at an early stage before they become symptomatic. Consequently, seca mBCA not only helps in improving the therapy, it also leads to enhanced quality of life.