Dehydration

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Dehydration Slideshow

Quick GuideDehydration Pictures Slideshow: Causes, Symptoms and Tips to Stay Hydrated

Dehydration Pictures Slideshow: Causes, Symptoms and Tips to Stay Hydrated

What are the complications of dehydration?

Complications of dehydration may occur because of the consequences of dehydration, and/or because of the underlying disease or situation that causes the fluid loss.

Kidney failure

Kidney failure is a common occurrence and often is reversible, if it is due to dehydration and is treated early. As dehydration progresses, the volume of fluid in the body decreases, and blood pressure may fall. This can decrease blood flow to vital organs including the kidneys, and like any organ with a decreased blood flow; it has the potential to fail to do its job.

Coma

Decreased blood supply to the brain may cause confusion and even coma. 

Shock

When the fluid loss overwhelms the body's ability to compensate, blood flow and oxygen delivery to the body's vital organs become inadequate and cell and organ function can begin to fail. If enough organs begin to malfunction, the body itself may fail and death can occur.

Heat-related illnesses and associated complications

In heat-related illness, the body's attempt to cool itself by sweating may cause dehydration to the point that muscles may go into spasm (heat cramps). It is often the muscles that are being stressed that will spasm (for example, in people who work outside in a hot environment, arm and leg muscles may spasm from lifting and moving heavy objects or equipment; in athletes, leg muscles may cramp from running). As fluid loss increases, the symptoms of heat exhaustion can occur and include weakness, lightheadedness, nausea, and vomiting. If the symptoms are recognized and the patient isn't moved from the heat and rehydrated, the situation may progress to heat stroke. The patient will stop sweating, have a change in mental status that includes confusion and coma, and the body temperature may spike to 106 F (41 C) or higher. Heat stroke is a true medical emergency and 911 or the emergency response system should be activated immediately in this situation.

Electrolyte abnormalities

In dehydration, electrolyte abnormalities may occur since important chemicals (like sodium, potassium, and chloride) are lost from the body through sweat. For example, patients with profuse diarrhea or vomiting may lose significant amounts of potassium, causing muscle weakness and heart rhythm disturbances. The health care professional may decide to monitor electrolyte levels by checking blood tests. Examples of symptoms caused by abnormal electrolyte levels include muscle weakness due to low potassium, heart rhythm disturbances due to either low or high potassium, and seizures due to low (hyponatremia) or high sodium (hypernatremia). In many patients with dehydration, the kidneys are able to compensate and regulate electrolyte levels.

It is important to remember that dehydration does not occur quickly, and sometimes it may take hours to slowly correct the fluid deficit and allow the electrolytes to redistribute themselves appropriately in the different spaces in the body. If rehydration is done too slowly, the patient may remain hypotensive and in shock for too long. If done too quickly, water and electrolyte concentrations within organ cells can be negatively affected, causing cells to swell and eventually become damaged.

Medically Reviewed by a Doctor on 6/30/2015

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