| Body Water |
Article Index for Body |
Website Links For Body |
Information AboutBody Water |
|
In diseased states where body water is affected, the compartment or compartments that have changed can give clues to the nature of the problem. Body water is regulated by Hormone s, including Anti-diuretic Hormone (ADH), Aldosterone and Atrial Natriuretic Peptide . There are many methods that can be used to determine body water. One way to get a simple estimate is by calculation. CALCULATION OF BODY WATER In individuals of normal weight, water is abundant in most parts of the body, except in Adipose Tissue ( Fat ). These calculations are for adults of average build, and are inappropriate for Obese or overly muscular people. These proportions are very simplified and use round numbers for quick calculation. In men about 55% of the body mass is water. This value is about 51% in women due to a higher proportion of body fat. This is the ''total body water''. Body water is broken down into the following ''compartments:''1
MEASUREMENT OF BODY WATER Dilution and equilibration Total body water can be determined using Flowing Afterglow Mass Spectrometry FA-MS measurement of Deuterium abundance in breath samples from individuals. A known dose of deuterated water ( Heavy Water , D2O) is ingested and allowed to equilibrate within the body water. The FA-MS instrument then measures the deuterium-to-hydrogen (D:H) ratio in the exhaled breath water vapour. The total body water is then accurately measured from the increase in breath deuterium content in relation to the volume of D2O ingested. Different substances can be used to measure different fluid compartments:
Bioelectrical impedance analysis Another method of determining total body water percentage (TBW%) is via Bioelectrical Impedance Analysis (BIA). In the traditional BIA method, a person lies on a cot and spot electrodes are placed on the hands and bare feet. Electrolyte gel is applied first, and then a current of 50 kHz is introduced. BIA has emerged as a promising technique because of its simplicity, low cost, high reproducibility and noninvasiveness. BIA prediction equations can be either generalized or population-specific, allowing this method to be potentially very accurate. Selecting the appropriate equation is important to determining the quality of the results. For clinical purposes, scientists are developing a multi-frequency BIA method that may further improve the method's ability to predict a person's hydration level. New segmental BIA equipment that uses more electrodes may lead to more precise measurements of specific parts of the body. CONDITIONS ASSOCIATED WITH ABNORMAL BODY WATER SEE ALSO REFERENCES EXTERNAL LINKS |
|
|