Among the rarest symptoms and conditions that can be found, adipsia is one of the most surprising. This medical problem is the complete absence of thirst, even when the body needs urgent hydration.
The theories behind this bizarre problem involve both problems in specific areas of the brain and issues with the regulation of neurotransmitters, blood salts, and hormones.
Below, we’ll take a closer look at what adipsia is, what causes it, why it’s hard to diagnose, and what its treatment is.
What is adipsia?
Adipsia, also known as hypodipsia, is a medical condition in which the patient has a complete absence of thirst, i.e. a lack of desire to drink fluidsEven when the body has little water or contains an excessive amount of salts. It is normal not to feel thirsty throughout the day in case you are well hydrated, however, in adipsia the problem is that there is a physiological urge to drink water, but this does not. is not felt.
This medical condition has been linked to an increase in osmolarity or the concentration of solutes in the urine, which stimulates the secretion of antidiuretic hormone (ADH) from the hypothalamus to the kidneys. As a result, the person does not have the subjective feeling of thirst, because it receives physiological signals indicating that the body has sufficient water.
Adipsia is a fairly rare symptom, and although some theories have been raised as to why it occurs, it is not yet clear what the process behind the onset of this condition is. What is known is that it may be linked to medical conditions such as diabetes insipidus and hypernatremia, that is, high levels of sodium in the blood. too much it is known that in the absence of seven, the hypothalamus, pituitary and corpus callosum may be involved..
There are two main theories to explain the onset of adipsia. One of them has to do with the neurotransmitter dopamine, which is closely related to eating behavior, while the other indicates dysfunctions and injuries in the hypothalamus.
Dopamine is a neurotransmitter that has been linked to eating behavior. The absence of this substance was studied in mice that were affected by the dopamine regulatory system, measuring the amount of food and water consumed by rodents without this substance.
Research has shown that the dopamine-free mice, as they neither ate nor drank on their own because they had no interest in doing so, would have starved and dehydrated if they had not been forced to feed.
In these same mice, the scientists injected the chemical precursor of dopamine, L-DOPA, lacto, which caused the rodents to feed on their own. Although the mice were born without a dopaminergic system, injection of the substance elicited the feeding behavior.
Although dopamine deficiency caused adipsia in mice, those with low levels of this substance were not adiptic. They wanted to eat and drink when their bodies needed it. Based on this, we wondered if dopamine is really the determining substance in the absence of thirst.
However, another theory suggests that dopamine is heavily involved in thirst, especially in the black streak path. If this route is seriously degraded, the animal becomes adiptic, aphagic and loses interest in exploring the surroundings.
The hypothalamus is an important region of the brain, in which is the area that regulates thirst, especially its front part. This structure is close to osmoreceptors, which regulate the secretion of the antidiuretic hormone or ADH.
DHA is one of the main mechanisms by which sodium levels are regulated and osmolar homeostasis is achieved. When small increases in osmolarity occur in the blood serum, this hormone is secreted.
Thirst is said to be the subjective sensation resulting from increased osmolarity levels of blood serum, which led to increased secretion of antidiuretic hormone. It is an indicator that fluids must be consumed to return to homeostasis.
Based on this, adipsia could be explained by lesions of the hypothalamic regions involved in the regulation of thirst. These injuries can be congenital, acquired, due to trauma, or even some type of surgery.
It can also be explained by the presence of a bronchial tumor which causes the syndrome of inadequate secretion of antidiuretic hormone, hydrocephalus and stroke near the hypothalamus.
Diagnosing adipsia is not an easy task because there is no set of physical and objective signs that clearly establish that the patient is suffering from this condition, Except for his lack of thirst. This condition is, in turn, a symptom and can occur along with other medical conditions such as hyperpnea, muscle weakness, insomnia, lethargy, and seizures.
As it has been linked to hypothalamus dysfunctions, in case the patient indicating that he is not thirsty has a history of brain tumors or birth defects, the alarms are activated. It is also important make sure the person has not suffered a brain injury recent which can explain the symptom, verifying it with neuroimaging techniques.
To check for organic issues, it is necessary to perform various analyzes. Among the tests that can be performed we have electrolyte analysis, blood urea nitrogen analysis and monitoring creatinine levels. Osmolarity in blood serum and urine is also monitored, as is the presence of hormones in the blood, such as vasopressin. In fact, vasopressin is an indicator of adipsia because in this condition it is at very low levels.
As we have already mentioned, people with adipsia exhibit a pathological lack of thirst, although they do not have physical difficulties that prevent them from consuming fluids. By not receiving the physiological signal to drink if necessary, people with regular exercise need to be educated and trained in a fluid intake routine to avoid dehydration. This is not to get them to drink all the time, but to do so from time to time, to make sure that the body has enough fluid.
There is no medication to cure adipsia, although as long as the person is properly hydrated, the presence of this condition does not imply serious organ damage. The patient can exercise and continue with their normal diet, incorporating the necessary water, unless otherwise directed by their doctor.
People with diabetes insipidus may use the hormone desmopressin acetate intranasally or orally., Which is molecularly and functionally similar to vasopressin, which makes the person thirsty when it is necessary to hydrate the body. Desmopressin helps the kidneys reabsorb water.
- Koeppen BM, Stanton BA (2019), Regulation of osmolality of body fluids: regulation of water balance. A: Koeppen BM, Stanton BA, eds. Renal physiology. 6th ed. Philadelphia, PA: Elsevier: Chapter 5.
- Słodki I, Skorecki K (2016). Water and sodium homeostasis disorders. A: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders ;: chapter 116.