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Dehydration of the body
Medical expert of the article
Last reviewed: 07.07.2025
Dehydration is a decrease in the total water content when its loss exceeds its intake and formation, or when its sharp redistribution occurs.
Dehydration of the body accompanies many pathological conditions, complicating their course, since it is characterized by thickening of the blood due to a decrease in the BCC, with a violation of microcirculation and: tissue metabolism. Dehydration of the body symptoms are already expressed with a fluid imbalance of 1.5 liters of water (2.5% of body weight) - mild; moderate degree develops with a loss of 4-4.5 liters of water (3-6% of body weight); severe degree is noted with a loss of 5-7 liters of water (7-14% of body weight). Large loss of water leads to death, since cellular changes are irreversible.
Depending on the pathogenesis, dehydration is divided into 3 types:
Dehydration of the isoosmolar type, when water and electrolytes are simultaneously lost through the gastrointestinal tract, skin, kidneys, respiratory tract, with multiple trauma, infections, bleeding. Hypovolemic syndrome and signs of general dehydration come to the fore: dry mucous membranes, decreased skin turgor, oliguria or anuria, acidosis and azotemia, cerebral disorders in the form of apathy, adynamia, up to coma. Depending on the severity of dehydration, a decrease in blood pressure and central venous pressure, an increase in hematocrit are noted, but the sodium content and osmolarity of the blood remain normal.
Hyperosmolar dehydration, when more water is lost than electrolytes. This dehydration may occur with insufficient fluid intake (dry eating), significant water loss through the gastrointestinal tract (profuse diarrhea, laxative intake), kidneys (diuretics; diabetes insipidus), skin (profuse sweating), respiratory tract (intensive breathing), in cases of intensive therapy with the introduction of hyperosmolar solutions or with insufficient replenishment of the disturbed hydrobalance. Symptoms of cellular dehydration (pronounced thirst, increased body temperature; nervous system disorders) and extracellular dehydration (moderate hypotension, tachycardia, dry mucous membranes, decreased skin turgor, oliguria) are observed. Blood pressure and central venous pressure decrease moderately, signs of blood thickening come to the fore: increased hemoglobin, hematocrit, blood protein. Signs of hyperosmolarity: increased plasma and urine osmolarity, increased sodium levels. Metabolic acidosis, quite pronounced, often decompensated, accompanied by azotemia.
Hypoosmolar dehydration, when electrolytes are lost more than water. This occurs with electrolyte loss through the gastrointestinal tract, skin, kidneys, adrenal insufficiency, some types of trauma, fistulas, and with intravenous administration of large amounts of hypoosmolar solutions. Signs of cellular hyperhydration come to the fore: vomiting, convulsions, cerebral edema, pulmonary edema, coma. Signs of extracellular dehydration are also expressed: hypotension, tachycardia, heart failure, oliguria, metabolic and respiratory acidosis, azotemia. A decrease in plasma and urine osmolarity and a decrease in plasma sodium levels are characteristic.
In all cases of dehydration, the patient should be referred or transferred to the intensive care unit.
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