Dipsesis is the medical term for excessive thirst. Conditions that cause extreme fluid loss and leave the body water-depleted trigger excessive thirst. Body water can be lost through excessive urination, vomiting, diarrhea, sweating and increased body temperature. A variety of conditions can cause a total body water deficit and excessive thirst.
Uncontrolled Diabetes Mellitus
Diabetes mellitus causes abnormally high blood sugar levels if not controlled with medication. Normally, the kidneys conserve blood sugar and it is not excreted in the urine. However, when the blood sugar is abnormally high, the kidneys are unable to handle the sugar overload. In this circumstance, sugar spills into the urine taking with it an excessive amount of body water. The body is left in a state of water depletion causing excessive thirst. Excessive thirst and urination along with weight loss and hunger are the classic symptoms of undiagnosed type 1 diabetes mellitus. The Juvenile Diabetes Research Foundation reports more than 15,000 children are diagnosed with type 1 diabetes annually in the U.S.
The kidneys are the workers that control water balance in the body, excreting excess water when present and conserving water when body levels are low. Although the kidneys do the work, the regulation of water balance is controlled by the hypothalamus, a small gland in the brain. The hypothalamus secretes antidiuretic hormone, which acts on the kidneys causing water conservation. With diabetes insipidus, antidiuretic hormone is not produced in sufficient amounts or the kidney does not respond to it. In either case, the kidneys excrete excessive amounts of water causing chronic, excessive thirst. Failure of the hypothalamus to produce sufficient antidiuretic hormone is a rare condition. In the text “Neuroendocrinology, Hypothalamus, and Pituitary,” Dr. Ball and Dr. Bayliss report the prevalence of hypothalamic diabetes insipidus is approximately one in every 25,000 people.
Many illnesses can cause an acute loss of body water, a condition called dehydration. Food poisoning and other diarrheal illnesses, heat exhaustion, burns and infections that cause high fever are examples. As total body water decreases, symptoms appear including dry mouth, fatigue, lightheadedness, confusion and extreme thirst. In moderate to severe dehydration, nausea and vomiting may develop complicating fluid replacement. If fluids cannot be taken by mouth, intravenous fluids may be required. Severe dehydration can be life-threatening. The Sabin Vaccine Institute reports more than 500,000 children die annually around the world of rotavirus, the most common cause of diarrhea-related deaths in children. Massive losses of total body water and resultant dehydration are the primary cause of death.