Diabetes insipidus is not a new term now. Many individuals suffer every year with this disorder. Diabetes insipidus is a disorder where a person experiences excessive thirst that results in excretion of large amount of diluted urine which is responsible for the reduction in the amount of the body fluid. It is commonly called as DI and there are various reasons that favour occurrence of DI in humans. The most prevalent type of diabetes insipidus is the neurogenic DI which is caused by the deficiency of the anti-diuretic hormone typically recognized as argentine vasopressin. Another type of DI is nephrogenic DI which is the result of non-responsiveness of the kidneys towards the vasopressin.
The symptoms of diabetes insipidus comprise excessive urination and feeling of frequent thirst. The symptom including excessive urination resembles that of the diabetes mellitus with a difference that no blood glucose is present in the urine. Blurring of the eye vision may also occur but is rare. Dehydration may also occur as a person is unable to conserve water resulting in loss of body water. The loss of water through frequent urination may persist throughout the day and may continue till night. The children suffering from DI may show loss of appetite, body weight, growth, fever, vomiting and diarrhea. Adult individuals with untreated DI may tend to remain healthy until the water loss is minimized but they are at greater risk of potassium ion depletion.
Diabetes insipidus may be diagnosed by testing the calcium level, bicarbonate level and the blood glucose level. The sodium ion is found to be comparatively high in the electrolyte test. The analysis of urine reveals dilute urine with low specific gravity and low electrolyte level. The fluid deprivation test reveals that whether the disorder is the result of excessive uptake of fluid or defect in the ADH production or due to unresponsiveness of the kidneys towards ADH. The fluid deprivation test also indicates the changes in body weight, urine output, and urine composition. The patients continue to urinate frequently in absence of any fluid intake. Desmopressin is given to the patients which is responsible for the reduction of the urine output and increases the osmolarity of the urine and the kidneys tend to function normally.
Electrolyte and volume homeostasis are the complex mechanisms of the human body that regulate the blood pressure and sodium and potassium ions in blood. Urine production is under the control of hypothalamus which secretes ADH from the supraoptic and the paravenrticular nuclei. After the synthesis of ADH, it is transported in the form of neurosecretory granules through the axons of hypothalamic neurons to the posterior lobe of the pituitary gland where it is stored to be used further. The ventromedial nucleus of the hypothalamus is responsible for the regulation of the thirst. Kidney is the main effector organ the fluid homeostasis. ADH is responsible for the absorption of the water into the bloodstream and concentrating the urine.
There are several forms of DI. One such type is the neurogenic diabetes insipidus which is commonly recognized as the central DI. It is caused when the production of the hormone vasopressin is lost in the brain. Other type is the nephrogenic DI which is the result of the failure of the response of the kidneys towards ADH. Third type of the diabetes insipidus is the gestational DI which is caused only during the period of pregnancy. It has been reported that all the pregnant ladies produce an enzyme vasopressinase in the placenta that breaks the ADH; this can attain many hazardous forms in the gestational DI. GDI in most cases is treated with desmopressin. Diabetes insipidus is also responsible for causing several dangerous diseases in the period of pregnancy like the pre-eclampsia, HELLP Syndrome and Acute fatty liver of pregnancy. These diseases are caused by the activation of the hepatic vasopressinase. Failure in the treatment of any of these diseases can lead to the death foetus. Another form of DI is the dipsogenic DI which occurs due to the defect or damage of the thirst mechanism that is controlled by the hypothalamus. This results in the abnormal intake of fluid and increase in the thirst which suppresses the ADH secretion resulting in increased production of urine. Desmopressin is ineffective for its treatement.
Central DI and gestational DI can be treated with the help of desmopressin but it is ineffective for the treatment of the nephrogenic diabetes insipidus. Indomethacin is used for the treatment of the nephrogenic DI. Several types of amilorides are available for the treatment of DI. Diabetes insipidus if treated carefully will be kept under control.
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