signs of dehydration include:
•Headaches
•Fatigue
•Loss of appetite
•Flushed skin
•Poor skin turgor
•Heat intolerance
•Lightheadedness
•Dry mouth and eyes
•Dark urine with strong odor(Kleiner, 1999)
Maintenance of fluid balance is essential to good health and recovery from surgery, illness or injury. Increased fluid losses are associated with:
•Chronic or acute infections
•Fever
•
•Vomiting
•Diarrhea
•Laxative abuse
•Gastric drainage
•Ileostomy
•Excessive urinary losses
•Diuretics
•Glycosuria
•Diabetes insipidus
•High-protein diet
•Environment
•Elevated ambient temperature
•Low humidity
The decrease in body fluids causes reductions in both the extracellular and intracellular fluid compartments. Clinical manifestations of dehydration are closely related to intravascular volume depletion. Without treatment, dehydration progresses to hypovolemic shock, organ failure and death (Ellsbury, 2003).
Assessment FOR Dehydration
Assessment for dehydration in the hospitalized patient or long-term care resident involves:
•Physical assessment
•Recent history of food and fluid intake
•Laboratory assessment
During a dehydrated state, there is less water in the body. The concentration of blood constituents increases. The laboratory tests may present a misleading picture of the individual’s nutritional status. There are three types of dehydration based on serum sodium:
•Hypertonic dehydration
•Isotonic dehydration
•Hypotonic dehydration
Hypertonic dehydration occurs when body water losses are greater than sodium losses. This can be due to reduced oral intake, excessive losses from sweating or prolonged high fever. The sodium concentration rises in the extracellular compartment, which draws water osmotically from the intracellular fluids. A summary of laboratory tests used to diagnose different types of dehydration follows on Table 4. Additional information about each laboratory test is in the next section of this text.
Isotonic dehydration occurs when the body loses equal amounts of sodium and water. Gastrointestinal disturbances causing extreme diarrhea and/or vomiting can trigger isotonic dehydration. This type of dehydration is often seen with food borne illness or severe bleeding. The serum sodium levels, serum osmolality and specific gravity levels are within normal ranges. These individuals are not thirsty and do not sense the need for more fluid. Both fluid and sodium are needed to rehydrate the patient. Refer to Table 4.
Hypotonic dehydration occurs when the body sodium loss exceeds water loss. This is sodium depletion or hyponatremia. It occurs in the patient who is taking diuretics, on sodium restricted diets, experiencing diarrhea or vomiting, has excessive sweating, a renal sodium-wasting syndrome or a combination of these contributors. There is typically a reduction in extracellular fluid volume. The laboratory tests indicate abnormally low serum sodium levels. Treatment includes giving water-electrolyte solutions to rehydrate the patient. Refer to Table 4.
Table 4. Screening for Dehydration
| Lab Test | Hypertonic | Isotonic | Hypotonic |
| Osmolality (S) | >Normal | WNL | < Normal |
| Sodium, (S) | > Normal | WNL | < Normal |
| Hemoglobin | > Normal | > Normal | > Normal |
| Hematocrit | > Normal | > Normal | > Normal |
| Albumin, (S) | > Normal | > Normal | > Normal |
| BUN | > Normal | > Normal | > Normal |
| Urine Specific Gravity | > Normal | > Normal | < Normal |
Key: WNL= within normal limits
Assessment FOR Overhydration
Overhydration occurs when there is an increase in the extracellular fluid volume. The fluid shifts from the extracellular compartment to the interstitial fluid compartment. This is called edema and is typically caused by one of these mechanisms:
•
•
•
•Lymphatic obstruction (following surgery)
•Organ failure (kidney or liver)
•
Overhydration is categorized by serum sodium concentration levels which reflect the composition of the fluids retained. Each type of overhydration presents different pathophysiologic effects. There are three types of overhydration:
•Isotonic
