Body Water Percentages and Ratios

Body water takes up the largest share of body composition, carries oxygen and essential nutrition to cells, and removes waste materials out of the body. Even a minor loss of 20% of body water could cause a serious death risk. Therefore, it is vital to keep your body constantly hydrated for proper body functioning. The standard range of body water is calculated considering the proportion of current total body water percentage compared to standard weight. * Ref. Nello et al.(1945) The Body Water and Chemically combined nitrogen content in relation to fat content

Intracellular Water: Among the body water, intracellular water is the water located inside cell membranes and is one of the constituents of somatic cells. In patients with hydrops abdominis or edema that usually causes an abnormal body water increase, muscle mass may be overestimated by the increased body water. Intracellular water does not change largely, but it is common that extracellular water increases abnormally in the patients, so that it is good to check intracellular water when assessing muscle mass for accurate muscle analysis.

Extracellular Water: Among the body water, extracellular water is the water located outside cell membranes and consists of tissue fluid, lymph fluid and water in plasma. In general, extracellular water accounts for approximately 40% of the body water, but it may largely increase by disease such as edema.

Extracellular Water Ratio: Extracellular water ratio is an indicator of the water balance in the body. It refers to the ratio of extracellular water to total body water.

Extracellular Water Ratio = Extracellular Water / Total Body Water

Extracellular water refers to water present outside the cell membrane amongst total body water and is composed of substances such as tissue water, lymph water, and water within plasma. The extracellular water ratio of a healthy person is between 0.36~0.39, but when an edema occurs in the human body, the extracellular water ratio may exceed the standard range due to excessively increased extracellular water. Edema is a phenomenon where the body’s water distribution is unbalanced and the body gets swollen. Edema accompanies the progression of a disease but is not referred to as a disease in itself. Some of the disease that causes edema are heart disease, renal (kidney) disease, liver disease, endocrinopathy, etc. It can also be caused by malnutrition or aging, thus when the extracellular water exceeds the standard ratio, expert consultation or getting a detailed diagnosis is recommended