When most people think of diabetes, they associate the term with high sugar levels. However, this kind of diabetes is called diabetes mellitus, as diabetes is a general term that refers to abnormalities with the urine. Diabetes insipidus is an entirely different disorder that can be caused by problems with the kidneys or with hormone release.
Diabetes Inspidus
Diabetes inspidus is a condition in which the body is unable to properly handle fluids. The end result is a massive quantity of urine produced. Large quantities of urine can cause dehydration and massive thirst. As a result of the fluid loss, electrolyte imbalances (too much sodium, potassium or calcium) in the body may also occur, which can be fatal if left untreated.
Kidneys and ADH
The kidneys are responsible for controlling the body's fluid load. When the body's overall fluid level is low, the kidneys work to concentrate the urine so as to prevent the loss of water through urination. The kidneys concentrate the urine by absorbing compounds such as sodium, which causes water to be reabsorbed as well due to a force called osmotic pressure. The kidneys can be instructed to absorb more sodium (and thus more water) via the action of a hormone called antidiuretic hormone (also known as vasopressin), which is produced by the hypothalamus in response to low levels of water in the body.
Nephrogenic Diabetes Inspidius
Diabetes insipidus can be caused by a variety of dysfunctions. In the case of nephrogenic diabetes insipidus, the kidneys become damaged and no longer respond properly to vasopressin. As a result, the kidneys are unable to respond to signals that the body is dehydrated and instead produce large quantities of urine.
Causes
Nephrogenic diabetes insipidus can be due to a number of causes. One cause is hereditary: The X chromosome can develop a genetic mutation that causes the kidneys to not respond to vasopressin. Because males only have one X chromosome, hereditary nephrogenic diabetes insipidus tends to affect males. It can also be caused by certain medications, such as lithium. Finally, nephrogenic diabetes insipidus can be caused by chronic kidney disease, such as polycystic kidney disease, severe kidney infections, sickle cell anemia, and an autoimmune disorder known as Sjogren's syndrome.
Diagnosis and Treatment
Nephrogenic diabetes insipidus is usually diagnosed based on its symptoms (extreme thirst and massive urine output) as well as testing the urine for high sodium levels coupled with otherwise dilute urine. Blood tests can also detect vasopressin. High levels of vasopressin combined with high urine output indicate nephrogenic diabetes insipidus.
In general, the best treatment is to have the patient drink large quantities of water each day to prevent dehydration. Non-steroidal anti-inflammatory drugs and thiazide diuretics can also be used to help lower the daily urine output.
