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Diseases With Excessive Thirst

Jun 9, 2010 | By Ruth Coleman, M.D.

Drinking water on a daily basis is essential to proper body functioning. Therefore when people experience prolonged and excessive thirst, it can be a sign of illness. There are several diseases in which excessive thirst is a common symptom. Usually it is related to a loss of fluids, which causes a thirst response as the body attempts to replace the fluid that was lost.

Diabetes Mellitus

People with diabetes mellitus have hyperglycemia, or high levels of glucose in their blood. This disease is categorized as either type I or type II diabetes.
Excessive thirst, or what is referred to as polydipsia, is a common sign of both types of diabetes. Hyperglycemia leads to glucose in the urine and subsequent frequent urination as the body tries to correct the hyperglycemia by ridding itself of the excess glucose. This causes excessive thirst because the body is also trying to replace the lost fluids.
In type I, an autoimmune process in which the body attacks itself destroys the beta cells of the pancreas, according to Merck Manuals. The beta cells secrete insulin, which moves glucose from the blood into the cells and tissues. Only the brain, liver and red blood cells do not need insulin in order to receive glucose.
People with type II diabetes have beta cells, but their cells and tissues do not respond to insulin like they should. Their tissues are resistant to insulin. After some time, the amount of insulin released by the beta cells cannot keep up with the resistance of the cells and tissues, and hyperglycemia develops.

Diabetes Insipidus

Antidiuretic hormone, or ADH, is secreted by the posterior pituitary gland of the brain. ADH directs the kidneys to hold water. In people with nephrogenic diabetes insipidus, the kidneys do not respond to ADH, writes Elizabeth Corwin, Ph.D. in "Handbook of Pathophysiology." This can happen because of kidney disease, low levels of potassium or high levels of calcium in the bloodstream, or genetic defects. Because the kidneys do not hold onto water, people with this condition will urinate a lot. In response, they will have an excessive thirst.
In central diabetes insipidus, the posterior pituitary gland does not secrete ADH. This is due to an autoimmune process, genetic defect, tumor or infection. As a result, the kidneys do not receive the message to retain water. This results in frequent urination and excessive thirst to replace the lost fluids.

Primary Hyperaldosteronism

Primary hyperaldosteronism is a common disease that causes approximately 5 to 10 percent of all hypertension cases in America, according to "Current Medical Diagnosis & Treatment." Aldosterone is a hormone made in the outer part of the adrenal gland, called the adrenal cortex. It makes the kidneys retain sodium and release potassium. Having low levels of potassium in the bloodstream for a period of time, however, makes the kidneys resistant and unresponsive to ADH. People with this disease frequently urinate and have excessive thirst.

Sepsis

In sepsis, bacteria in the body spread to the bloodstream. As the bacteria circulate, the systems in the body respond to fight the infection. But as explained by the Merck Manuals, sepsis can lead to the failure of organs and shock. Blood pressure can drop very low and the body can lose a lot of fluid from the bloodstream. In response to the loss of fluids, excessive thirst develops.

Psychogenic Polydipsia

The "Handbook of Pathophysiology" explains that some psychiatric disorders, especially schizophrenia, can cause excessive thirst. When this occurs, it is referred to as psychogenic polydipsia. Physicians do not yet know the reason for this disorder that is characterized by a compulsion to drink large amounts of water. If not controlled, sufferers may develop seizures or go into a coma as the high volume of water consumed severely reduces sodium levels in the bloodstream.

References

Article reviewed by Libby Swope Wiersema Last updated on: Jun 9, 2010

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