How is OH calculated?
A. The BCM – Body Composition Monitor expresses the body weight in terms of lean tissue mass (LTM – mainly muscle), adipose tissue mass (ATM – mainly fat) and overhydration (OH). Each of these compartments has a specific composition and contains a known quantity of water per mass of tissue. OH is almost 100% extracellular water, whereas the water of LTM and ATM consist of differing proportion of extracellular and intracellular water in addition to solid components. Healthy individuals are considered to be “normally hydrated” and therefore have virtually no overhydration. These individuals may be characterized in terms of ATM and LTM only. However, in pathophysiological conditions the presence of excess fluid that may accumulate has to be taken into consideration. Excess fluid represents an expansion of only the extracellular water, whereas ICW remains unchanged. The excess fluid may reside within adipose tissue or lean tissue raising the hydration of the respective tissue above the “no
