Dehydration

Excessive loss of body water. Diseases of the gastrointestinal tract that cause vomiting or diarrhea may, for example, lead to dehydration. There are a number of other causes of dehydration including heat exposure, prolonged vigorous exercise (e.g., in a marathon), kidney disease, and medications (diuretics). One clue to dehydration is a rapid drop in weight. A loss of over 10% (15 pounds in a person weighing 150 pounds) is considered severe. Symptoms and signs of dehydration include increasing thirst, dry mouth, weakness or lightheadedness (particularly if worse on standing), and a darkening of the urine or a decrease in urination. Severe dehydration can lead to changes in the body’s chemistry, kidney failure, and become life-threatening. Dehydration due to diarrhea is a major cause of morbidity (disease) and mortality (death) in children. The young child has a more rapid turnover of body fluids than an adult. In rehydrating a child, there is less margin for error than for an adult. The younger the child, the more careful the rehydration must be. Cases that demand particular attention to detail are those in which organ function (especially skin, heart, brain, or kidney) is critically compromised. Overhydration may be as serious as severe dehydration in children; the rehydration should therefore be done under medical supervision. The best way to treat dehydration is to prevent it from occurring. If one suspects fluid loss is excessive, notify a physician. Intravenous or oral fluid replacement may be needed.

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1. Deprivation of water. SYN: anhydration. 2. Reduction of water content. 3. SYN: exsiccation (2). 4. SYN: desiccation.

- absolute d. actual water deficit as measured by a difference from the normal or from a given water content.

- relative d. water deficit relative to content of solutes contributing effective osmotic pressure; a state of increased effective osmotic pressure of body fluids.

- voluntary d. that physiologic lag or deficit that results when sensations of thirst are not strong enough to bring about complete replacement of water loss, as in rapid sweating.

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de·hy·dra·tion .dē-hī-'drā-shən n the process of dehydrating esp an abnormal depletion of body fluids

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n.

1. loss or deficiency of water in body tissues. The condition may result from inadequate water intake and/or from excessive removal of water from the body; for example, by sweating, vomiting, or diarrhoea. Symptoms include great thirst, nausea, and exhaustion. The condition is treated by drinking plenty of water; severe cases require oral rehydration therapy or intravenous administration of water and salts (which have been lost with the water).

2. the removal of water from tissue during its preparation for microscopical study, by placing it successively in stronger solutions of ethyl alcohol. Dehydration follows fixation and precedes clearing.

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de·hy·dra·tion (de″hi-draґshən) [de- + hydration] 1. removal of water from a substance. 2. the condition that results from excessive loss of body water. Cf. desiccation and xerosis.