The sensation of thirst is one that all humans experience, and it’s a natural neurological signal from the body that we need to take in more fluids. But, when our thirst becomes excessive or prolonged, what is our body trying to tell us?
The basics of thirst
In the brain, a small collection of cells named the lamina terminalis can detect the levels of both fluid and sodium in the body at any given moment, and if fluid levels are deemed low, the drive to drink is initiated through the sensation of thirst. The lamina also processes information sent from other parts of the brain regarding blood pressure, blood volume and other important aspects of homeostasis.
The balance of sodium and other electrolytes is key to many bodily functions, and when fluid levels are too low or high, electrolyte levels are impacted by relative dilution or concentration and can trigger all manner of physiological responses, some of which can be problematic or even life-threatening.
Thirst is triggered under many conditions, and the drive to replace lost fluids keeps our bodies functioning optimally. So, when thirst is excessive (polydipsia), something is amiss.
Causes of excessive thirst
Excessive or constant thirst are signals that we need to pay close attention to. Some potential causes of these symptoms are:
- Diabetes mellitus
- Exercise
- Spicy foods
- Vomiting and diarrhea
- Significant blood loss
- Poor fluid intake due to various causes such as dementia, or certain mental illnesses
- Burns
- Heart, liver or kidney failure
- Anemia
- Cushing’s syndrome
- Sjogren’s syndrome
- Pregnancy
- Smoking
- Dehydration
- Kidney failure
- Diabetes insipidus
In diabetes, excess sugar…
in the blood spills into the kidneys and pulls fluids with it, leading to excessive urination (polyuria) and fluid loss.
In diabetes insipidus (which is not directly related to diabetes mellitus, the form of diabetes we generally refer to), the kidneys are unable to conserve fluids and excessive urination—and thirst to replace lost fluids—result.
Acute dehydration can lead to delirium, kidney stone formation, seizures, and other potentially life-threatening conditions.
There are many causes of excessive thirst, and symptoms of this condition must be taken seriously and assessed, diagnosed and treated appropriately.
Treating excessive thirst
When a patient is experiencing pathological levels of thirst, a medical provider will run a number of laboratory tests, the most common of which will include a check for diabetes, electrolyte imbalances and other abnormalities or conditions.
If diabetes is detected, treatment with diet, medications and lifestyle changes will be initiated. If failure of the heart, liver or kidneys is found to be the cause, these can be serious and must be aggressively addressed. And, when the only cause appears to be dementia (some individuals with dementia will forget or refuse to drink), behavioral interventions will be needed.
Dehydration can be caused by strenuous exercise, heat exposure, burns and other causes, and is usually treated with intravenous (IV) fluids and other measures. Excessive blood loss (or hemorrhage) calls for replacement of fluids in the form of donated blood and various formulations of IV fluids.
Respect and respond to thirst
Thirst is natural, yet when it is excessive, constant or prolonged, action must be taken.
Infants, children, young people and adults of all ages can suffer when the causes of excessive thirst are not addressed. Thus, this normal biological drive must be respected and responded to when it appears to be out of balance, and is sending us the warning signs that immediate action and prudent intervention are called for.