Diabetes insipidus is a rare condition that affects an estimated 1 in 25,000 people worldwide.
Adults are more likely to develop the condition, however, it can occur at any age. Despite sharing the same signs and symptoms, it is not related to diabetes.
Diabetes insipidus is caused by complications with the chemical vasopressin (AVP), also known as antidiuretic hormone (ADH).
The hormone AVP is produced by the hypothalamus and stored in the pituitary gland (both glands are located in the brain). The healthy AVP hormone controls water in the body by regulating the kidney’s urine production.
As the body’s water level decreases through urination, the pituitary gland releases AVP which works to reduce excessive water loss. In diabetes insipidus, AVP erroneously regulates water levels, causing too much urine to pass from the body. This can result in dehydration.
The two types of diabetes insipidus are:
- Cranial diabetes insipidus, where the body doesn’t produce enough AVP
The most common causes are head injury, a brain tumor causing damage to the pituitary gland or hypothalamus, or complications resulting from brain or pituitary surgery, and—in about 1/3 of cases—undetermined causes.
Less common, accounting for another 1/3 of cranial diabetes insipidus cases, is a rare genetic disorder called Wolfram syndrome that can occur as a result of a stroke or a near-drowning accompanied by a sudden loss of oxygen; cancers that spread to the brain from another part of the body; brain-damaging infections such as encephalitis and meningitis.
Another 1/3 of cases are called idiopathic cranial diabetes insipidus. While such cases are considered undetermined, they are thought to be related to the immune system.
- Nephrogenic diabetes insipidus, where the liver doesn’t respond properly to correct levels of AVP that the body produces
The causes of nephrogenic diabetes insipidus are varied. Tiny structures in the kidneys contain nephrons that work to filter waste from the blood, help make urine, and also control the amount of water that is reabsorbed into the body. In nephrogenic diabetes insipidus, the nephrons are unresponsive to AVP’s signals, resulting in excessive water loss through urine.
Nephrogenic diabetes insipidus can present itself at birth (congenital) due to genetic abnormalities, or it can present itself later in life (acquired) as a result of an external factor. A common external factor is lithium, often used as a therapy to treat bipolar disorder. A less common external factor is when people take tetracycline. Other factors include kidney infection (pyelonephritis), or ureteral obstruction, where the ureters that connect the bladder and kidneys become blocked, causing too much calcium in the blood (hypercalcemia), or causing insufficient potassium in the blood (hypokalemia).
The most common symptoms of diabetes insipidus are
- excessive thirst;
- excessive urination, as often as every 15-20 minutes;
- pale urine
In extreme cases, a patient can pee up to 20 liters in 1 day.
These symptoms undoubtedly result in the daytime and nighttime disruptions that may cause loss of appetite, irritability and sleepiness for youth and adults. The very young may show signs of crying and/or irritability. Parents might notice other symptoms such as unexplained weight loss, slow growth, and elevated body temperature (hyperthermia).
The symptoms of diabetes insipidus may resemble other conditions, particularly those of diabetes. Therefore, it is important to see a healthcare provider who may refer a patient to an endocrinologist, a specialist in hormonal diseases and conditions.
The physician will conduct a number of tests that may include:
- Water deprivation (Vasopressin), a test that involves prohibiting liquid for several hours
Testing will assess the amount of urine produced over time and its color. Further testing can assess the levels, if any, of glucose (blood sugar), potassium and calcium. Upon assessment of the reaction(s) to water deprivation, a patient may receive an injection containing a small dose of the hormone AVP that may stop excessive urination. If excessive urination stops, the patient is likely in need of AVP and will be diagnosed as having cranial diabetes insipidus.
If, however, a patient continues displaying excessive urination, the patient might be diagnosed with nephrogenic diabetes insipidus. This means that the condition likely involves the liver for which further testing will be performed to include:
- Blood test to assess ADH levels and possibly sugar (glucose) levels in the blood
- Urine test to assess the levels of glucose, potassium, and calcium
High levels of glucose in the blood and/or urine might indicate diabetes. If so, further testing may be conducted. However, if test results point to diabetes insipidus, indicated by diluted urine and unhealthy levels of substances in urine or blood—such as high calcium or low potassium—then the doctor will perform other tests to determine the type of diabetes insipidus, cranial diabetes insipidus or nephrogenic diabetes insipidus.
- Magnetic Resonance Imaging (MRI) can scan the body to provide internal images, including images of the brain. If the physician notes possible damage to the pituitary gland or the hypothalamus, an MRI may be ordered. If any damage or abnormality is detected, treatment will be ordered.
There are several treatments aimed at reducing the amount of urine and also controlling other symptoms for patients diagnosed with diabetes insipidus.
Mild diabetes insipidus is treated by drinking more water, an amount determined by the physician or endocrinologist.
In treating more severe cranial diabetes insipidus, the physician may prescribe desmopressin, a substitute for AVP. This manufactured version of AVP stops the kidneys from producing urine when the body’s water level is low, to avoid dehydration.
Desmopressin is available as a tablet, a spray, and as a melt-in-the-mouth tablet. Because the bloodstream absorbs nasal spray more effectively than tablets, the spray is a preferred method of treatment. Both the spray and the tablet form are prescribed one or more times a day. Although desmopressin is considered to be very safe, there are possible side effects that can include:
- stomach pain;
- runny or blocked nose;
- a feeling of sickness
If a patient drinks too much fluid or takes too much desmopressin, the body may retain excess water, resulting in:
- hyponatremia (too little sodium in the blood)
Hyponatremia symptoms include prolonged or severe headache, confusion, nausea, and vomiting. Patients showing signs of hyponatremia should call their physician immediately. Otherwise, seek help at a local clinic or ER.
In treating nephrogenic diabetes insipidus, a physician may discontinue lithium and/or tetracycline, or try alternative treatments. In mild cases, the doctor might recommend that a patient reduce salt, meat and other protein-rich foods like eggs, processed foods and nuts. The rationale is simple: such foods encourage dehydration. Limit dehydration by avoiding these foods and by also drinking plenty of water. In cases where the disorder isn’t inherited, correcting the underlying abnormality typically restores normal kidney function.
Treating more severe nephrogenic diabetes insipidus may require reducing the amount of urine a patient’s kidneys produce. The physician will prescribe a combination of a non-steroidal anti-inflammatory drug (NSAID) and thiazide diuretics. While NSAIDs (Ibuprofen is an example) reduce the kidney’s production of urine, thiazide diuretics draw excess water from the body through the process of removing chloride and sodium, thus increasing one’s urine flow.
Because a stomach ulcer may develop with NSAID use, doctors sometimes prescribe a third medication, a proton pump inhibitor (PPI).