DI also known as diabetes insipidus is actually a rare form of diabetes that is not linked to blood glucose-related diabetes mellitus, but has some of its symptoms and signs.
This is actually an uncommon disorder that leads to an imbalance of water in the body. That imbalance causes the excretion of large amounts of urine also known as polyuria and thirst after consuming fluids also known as polydipsia.
When it comes to diabetes mellitus, increased blood glucose induces the production of a big volume of urine to aid remove the excess sugar. On the other hand in diabetes insipidus, the water balance system in the body does not work properly.
Diabetes insipidus causes frequent urination which is the clearest and most common symptom. In extremely severe cases, urination can be more than even 20 L on a daily basis. Increased thirst comes as a secondary symptom, due to passing too much water.
Children who suffer from this condition might become listless and irritable, and also there is the possibility of vomiting and fever.
You should know that diabetes insipidus has more forms. These forms have a different causal mechanism and connect to the hormone vasopressin.
Central (vasopressin-sensitive or neurogenic) diabetes insipidus is a partial or total lack of production of vasopressin, the pituitary gland of the brain fails to secrete this hormone.
Nephrogenic diabetes insipidus has normal vasopressin secretion. However, there is a disordered response regarding the hormone from the kidneys.
Its primary symptom, excessive urine output, and polyuria might have other causes. However, these are usually ruled out before a diagnosis of diabetes insipidus is given. For instance, poorly managed or undiagnosed diabetes mellitus might lead to frequent urination.
When it comes to diabetes insipidus, polyuria causes polydipsia which is excessive thirst. Excessive intake of water by primary polydipsia in other cases might cause polyuria.
Examples of primary polydipsia are a disorder of thirst by lesions in the hypothalamus, which can also lead to adipic diabetes insipidus, and psychogenic polydipsia which is a psychological habit of consuming an excessive amount of water.
This can occur by an absent or lowered secretion of vasopressin which can be secondary or primary. Often the cause of the primary central diabetes insipidus is unknown.
Other causes occur from abnormalities found in the gene which is responsible for the vasopressin. Furthermore, secondary central diabetes insipidus is an acquired form of the condition by diseases that adversely affect the secretion of vasopressin.
For instance, different brain lesions which result from brain surgery and head injuries might lead to secondary central diabetes insipidus.
Same as central DI, the nephrogenic DI can be primary, secondary, or inherited. Nephrogenic affects the response of the kidneys to vasopressin.
The inherited form might affect all people, and in 90 percent of cases, it occurs as a result of the mutation in the AVPR2 gene. In rare cases, which is around 10 percent, the inherited form can occur as a result of the mutations in the aquaporin-2 (AQP2) gene.
The acquired form can reduce the ability of the kidneys to concentrate urine when then water needs to be conserved.
The secondary form might have different causes such as:
Pregnancy, in rare cases, can cause disturbance of vasopressin. This happens because the placenta releases an enzyme that degrades vasopressin. This effect shows during the 3rd trimester.
Also, pregnancy leads to a lower thirst threshold. Therefore women consume more fluids. Also, there are other normal changes during pregnancy that influence the response of the kidneys to vasopressin.
Gestational DI, affects only a couple of cases in every 100,000 pregnancies. Gestational DI resolves around 2 or 3 weeks after birth.
DI can lead to electrolyte imbalance. You should know that electrolytes are actually minerals in the blood like potassium and sodium which maintain the balance of the fluids found in the body.
DI can cause the body to retain little water in order to function properly, and that can lead to dehydration.