Diabetes insipidus

Diabetes Insipidus occurs in a person whose fluid regulation system gets damaged, and there exists no control in fluid intake and the amount of urine excreted.
The fluid regulation system in our body plays an important role of keeping balance in fluid intake and excretion of the fluid by the kidney, and volume and composition of the body fluids. Diabetes Insipidus occurs in a person when this system gets disrupted, i.e., the system does not function effectively. The person will not be able to control the fluids he consumes, nor will he be able to control the number of times he excretes his urine. Thus, it is a medical condition (endocrine disorder) caused due to the deficiency of a hormone named Vasopressin, an antidiuretic hormone (ADH) that is secreted by the pituitary gland in the brain, or development of insensitivity of the kidneys to the ADH hormone.

A large amount of highly-diluted urine is excreted because of the inability of the kidney to concentrate the urine. The amount of urine excreted remains high even if the amount of fluid intake is reduced to any level.

(Excessive urination in medical terms, is considered when a patient urinates more than 50ml of urine per kg of his/her body weight in an interval of about 2 hours; or in simple words, more than 14 liters a day.)

Causes

As mentioned earlier, this condition mainly occurs due to the following reasons:
Antidiuretic hormone deficiency in body that is secreted by hypothalamus in brain to maintain balance of water in urine and blood
If the kidneys lose their ability to recognize the antidiuretic hormones
People suffering from some kind of injury or a tumor in the brain (it can be either hereditary or caused by surgery or injury)
Diseased pituitary gland causing lowered production of ADH
Signs and Symptoms
The patient feels extremely thirsty, and continues to urinate day and night in an excessive amount.
The blood glucose level in urine unlike diabetes mellitus, is not high and doesn't taste sweet.
The patient also experiences blurred vision.
Symptoms in children include problems related to the physical growth, affected hunger, weight gain, diarrhea, vomiting, and fever.
Excessive urination in adults can lead to dehydration if not compensated with proper intake of liquid. People may wake up several times in the night to urinate.
Types
Central Diabetes Insipidus: A damaged hypothalamus causes abnormal behavior of thirst mechanism, leading to this condition.
Nephrogenic Diabetes Insipidus: This is caused due to the inability of the kidney to identify antidiuretic hormones.
Dispogenic Diabetes Insipidus: This is caused due to damage or improper behavior of the thirst mechanism (which is located in the hypothalamus).
Gestational Diabetes Insipidus: This is a rare form, and occurs only during pregnancy. An enzyme is produced in the placenta, which destroys antidiuretic hormones. This can lead to deficiency of ADH if the production exceeds the minimum level.
Diagnosis

Other than excess urination, the condition is pretty hard to diagnose, and it is even harder to confirm the underlying causes of the disease.

Your doctor may perform blood test for ADH, calcium bicarbonate and sugar level, urine test, etc., and examine the frequency and volume of urine. Magnetic Resonance Imaging of the patient's brain can also help. Your doctor may also direct you to an endocrinologist.

Treatment

Once it is confirmed that the patient is suffering from this health problem, the doctor may perform some additional tests to narrow down on the underlying cause. One such test available is Fluid Deprivation Test (includes study and analysis of fluid intake and urination, body weight, and other factors), which helps in finding out if the condition is caused due to lack of ADH in blood, kidney disorder, or improper fluid intake.

Your doctor may choose to administer the ADH level in your body and use a synthetic ADH hormone DDAVP, which can be taken through an injection, in a pill form, and can also be inhaled. The treatment may take some time to help the patient restore the normal level/volume of urination (it always depends on the response of patient's body to the treatment).

In case if the hypothalamus/pituitary gland is damaged and causing problem, your doctor may suggest you undergo a surgery to remove the damaged gland (or tumor on the gland if any). This mode of treatment is generally used in Central Diabetes Insipidus.

In the other types, medication or hormone therapy may show some good result, avoiding need for surgery.