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Dehydration

Last updated: December 7, 2020

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Dehydration (exsiccosis) is a state of decreased total body water. This decrease in total body water occurs in excess of sodium (also called “free water loss”), resulting in a hypertonic and hypernatremic state. The terms “hypotonic” and “isotonic” are sometimes incorrectly used to describe dehydration, but these terms are only associated with _Definitions"#Z2c4b7b192fbfa8d2679ddc134ed0e9c5" data-lxid="Ig0Y92">hypovolemia and hypovolemic shock. Dehydration most often affects children and the elderly. Treatment of dehydration involves correcting the free water deficit.

References:[1][2][3][4][5]

Clinical feature Mild dehydration Moderate dehydration Severe dehydration
Decrease in body weight < 3% 3–9%

> 9%

Symptoms Mental status Alert Restless, irritable Lethargic, confused
Thirst Slightly increased Thirsty; drinks eagerly Refuses to drink
Urine output Normal ↓ (dark concentrated urine) ↓↓
Signs specific to dehydration Eyes Normal Slightly sunken Significantly sunken
Tears (especially children) Normal Decreased Absent
Tongue Moist Dry Parched
Skin turgor Instant recoil Recoil within 2 seconds Recoil after 2 seconds; significant skin tenting
In infants: anterior fontanelle Normal Slightly sunken Significantly sunken
Signs of hypovolemia and hypovolemic shock Pulse rate Normal Mildly tachycardic Initially tachycardia → later bradycardia
Blood pressure Normal Normal; postural hypotension may be present Hypotension
Capillary refill time Normal (< 2 seconds) 2–3 seconds > 3 seconds
Extremities Warm Cool Mottled
Breathing Normal Tachypnea Tachypnea with deep breathing (Kussmaul breathing)

References:[3][4][6][7][8]

References:[3][4][7][9][10][11][12]

Patients who are _Definitions"#Z2c4b7b192fbfa8d2679ddc134ed0e9c5" data-lxid="Ig0Y92">hypovolemic as a result of severe dehydration require immediate fluid resuscitation with crystalloid solutions.

  1. Fluid resuscitation
  2. Correction of electrolyte abnormalities

References:[3][13][14][15]

References:[16][17][18][19]

We list the most important complications. The selection is not exhaustive.

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  12. Chiasson J, Aris-Jilwan N, Bélanger R et al. Diagnosis and treatment of diabetic ketoacidosis and the hyperglycemic hyperosmolar state. CMAJ. 2003; 168 (7): p.859–866.
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