Adipsia: characteristics, possible causes and treatment of this condition

This rare condition occurs in people who do not experience the sensation of thirst.

Among the rarer symptoms and conditions that can be encountered, adipsia is one of the most surprising.. This medical problem is the total absence of thirst, even when the body needs urgent hydration.

The theories behind this strange problem relate both to problems in specific areas of the brain and problems in the regulation of neurotransmitters, Blood salts and hormones.

Next we will see more in depth what is the adipsia, which are its causes, why it is difficult to diagnose it and which is its treatment.

What is adipsia?

Adipsia, also known as hypodipsia, is a medical condition in which the patient presents a total absence of thirst, i.e. there is a lack of desire to drink liquids, even when the body has little water or an excessive amount of salts.even when the body is low in water or has an excessive amount of salts. It is normal not to feel thirsty throughout the day if you are well hydrated, however, in adipsia the issue is that there is a physiological need to drink water, but you do not feel it.

This medical condition has been related to an increase in the osmolarity or concentration of solutes in the urine, which stimulates the secretion of antidiuretic hormone (ADH) from the hypothalamus to the kidneys. As a consequence, the person does not have the subjective sensation of thirst, since he/she receives physiological signals that the receives physiological signals that the body has enough water..

Adipsia is a fairly rare symptom and, although some theories have been put forward as to why it occurs, it is still not known for certain what the process behind the occurrence of this condition is. What is known is that it can be related to medical conditions such as diabetes insipidus and hypernatremia, that is, high levels of sodium in the blood. Also it is known that the hypothalamus, pituitary and corpus callosum may be involved in the lack of thirst..

Causes

There are two main theories to explain the occurrence of adipsia. One of them has to do with the neurotransmitter dopamine, which is closely related to eating behavior, while the other points to dysfunctions and lesions in the hypothalamus.

Dopamine

Dopamine is a neurotransmitter that has been linked to eating behavior.. The absence of this substance has been studied in mice whose dopamine regulation system has been affected, measuring how much food and water the rodents consumed without this substance.

The research showed that the mice without dopamine, since they did not eat or drink on their own because they had no interest in doing so, would have ended up dying of starvation and dehydration if they had not been forced to feed themselves.

In these same mice, the scientists injected the chemical precursor of dopamine, L-DOPA, which caused the rodents to start eating on their own. Although the mice were born without dopamine systems, injecting them with the substance awakened their feeding behavior.

Although the lack of dopamine caused the mice to show adipsia, those with low levels of dopamine were not adiptic. They felt like drinking and feeding when their organism needed it. On this basis, it has been questioned whether dopamine is really the determining substance in the absence of thirst..

Yet another theory suggests that dopamine is heavily involved in thirst, especially in the nigrostriatal pathway. If this pathway is severely impaired, the animal becomes adiptic, aphagic and loses interest in exploring the environment.

Hypothalamus

The hypothalamus is an important region of the brain in which the area that regulates thirst is located, specifically its anterior part.. This structure is close to the osmoreceptors, which regulate the secretion of antidiuretic hormone or ADH.

ADH is one of the main mechanisms by which sodium levels are regulated and osmolar homeostasis takes place. When there are low increases in blood serum osmolarity this hormone is secreted.

Thirst would be the subjective sensation resulting from increased blood serum osmolarity levels, which have led to increased secretion of antidiuretic hormone. This is an indicator that fluids should be consumed to return to homeostasis.

On this basis, adipsia could be explained by lesions in the hypothalamic regions involved in thirst regulation.. These lesions could be congenital, acquired, due to trauma or even due to some type of surgery.

It can also be explained by the presence of a bronchial tumor causing syndrome of inappropriate antidiuretic hormone secretion, hydrocephalus and stroke near the hypothalamus.

Diagnosis

Diagnosing adipsia is not a simple task due to the fact that there is no set of physical and objective signs to clearly establish that the patient suffers from this condition, except his lack of thirst.except for a lack of thirst. This condition is, in turn, a symptom, and may be accompanied by other medical conditions such as hyperpnea, muscle weakness, insomnia, lethargy and convulsions.

As it has been linked to hypothalamic dysfunctions, in case the patient indicating that he/she is not thirsty has a history of brain tumors or congenital malformations, alarm bells are set off. It is also important to also important to ensure that the person has not suffered a recent brain injury that could recent brain injury that could explain the symptom, by checking with neuroimaging techniques.

To check for organic problems, it is necessary to perform different tests. Among the tests that can be performed are electrolyte analysis, blood urea nitrogen analysis and creatinine level check.. Osmolarity in blood serum and urine is also monitored, as well as the presence of hormones in the blood, such as vasopressin. In fact, vasopressin is an indicator of adipsia, since in this condition it is found in very low levels.

Treatment

As we have already mentioned, people with adipsia show a pathological lack of thirst, although they do not have physical difficulties that prevent them from consuming liquids. By not receiving the physiological signal that they need to drink when necessary, adiptic people need to be educated, adiptic individuals need to be educated and trained in a fluid intake routine to avoid dehydration. to avoid becoming dehydrated. It is not a matter of making them drink all the time, but rather every so often, to ensure that the body has enough fluid.

There is no drug to cure adipsia, although, as long as the person is properly hydrated, the presence of this condition does not imply serious organic damage. The patient can do sports and continue with his normal diet, incorporating the necessary water, unless his doctor has indicated otherwise.

People suffering from diabetes insipidus have the option of using the hormone desmopressin acetate intranasally or orally.desmopressin acetate, which is molecularly and functionally similar to vasopressin, causing the person to feel thirsty when it is necessary to hydrate the body. Desmopressin helps the kidneys to reabsorb water.

Bibliographic references:

• Koeppen BM, Stanton BA (2019), Regulation of body fluid osmolality: regulation of water balance. In: Koeppen BM, Stanton BA, eds. Renal Physiology. 6th ed. Philadelphia, PA: Elsevier:chap 5.
• Słodki I, Skorecki K (2016). Disorders of sodium and water homeostasis. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders;:chap 116.