There are four types of diabetes insipidus including:
- Central or cranial diabetes insipidus, also called neurogenic diabetes insipidus
- Nephrogenic diabetes insipidus
- Dipsogenic diabetes insipidus due to malfunction of the thirst mechanism
- Gestational diabetes insipidus which occurs during pregnancy
Central or cranial diabetes insipidus
This occurs if there is a low level of vasopressin or antidiuretic hormone (ADH) in the body. The deficiency means the kidneys are not prevented from excreting large amounts of urine and instead large volumes of dilute urine are expelled, even when the body has become dehydrated. This also causes blood to lose water and become more concentrated and higher in salt. This results in dehydration and stimulation of the thirst centre in the hypothalamus of the brain which causes a person to drink more.
This is the most common type of diabetes insipidus and it is mainly caused by disease, infection or injury to the pituitary gland or the hypothalamus gland.
The causes of cranial diabetes insipidus include:
Nephrogenic diabetes insipidus
This condition describes when the ADH level in the body is normal but the kidneys do not respond adequately to the hormone. This may occur due to kidney damage or medications such as lithium reducing the expression of water channels in the kidneys called aquaporins.
Nephrogenic diabetes insipidus may be caused by:
Other types of diabetes insipidus
- Dipsogenic diabetes insipidus arises due to malfunction of the thirst mechanism. Damage to the hypothalamus or pituitary gland may lead to this condition.
- Gestational diabetes insipidus that occurs pregnancy as a result of the placenta producing vasopressinase - an enzyme that breaks down vasopressin (ADH). This leads to ADH deficiency. The symptoms usually resolve after childbirth.