Body fluids obesity

Creatinine excretion is intimately related to a relatively constant part of the body, the muscle mass. When studying the excretion of any metabolite, such as urea, calcium, or riboflavin, it might be undesirable to relate the amount of urinary metabolite to bodily weight, because the body contains compartments that are of minimal importance relative to metabolism. The body of an obese person contains a large amount of tissue (adipose tissue) that is inetaboiicaUy and biochemically irrelevant to the metabolism of compounds such as urea, calcium, and riboflavin. A person w hosc body contains excess body fluids also has extra mass that may be irrelevant to the metabolism of these as W cll as other compounds A meaningful comparison of excretion data from different subjects or from one subject at different times is facilitated by relating the data to urinary creatinine. 

Some general clinical conditions have an effect per se on the composition of body fluids. These conditions may exist in addition to the primary complaint that prompted a patient s admission to the hospital For example, obesity, blindness, fever, shock and trauma, and transfusions and infusions all affect laboratory results. 

The volume ratio interstitial intracellular water varies with age and body weight On a percentage basis, interstitial fluid volume is large in premature or normal neonates (up to 50% of body water), and smaller in the obese and the aged. 

Petersen VP. Body composition and fluid compartments in normal, obese and underweight human subjects. Acta Med Scand 1957 108 103-11. 

Thus pregnancy presents a multitude of changes for the expectant mother and places her at risk for several fluid, electrolyte, and acid-base imbalances should any of the body s compensatory mechanisms fail. Additionally, any preexisting conditions, such as obesity, atherosclerosis, or prediabetes, could convert to fully active conditions. 

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