Overview: What is diabetes insipidus?
If it is very hot or you are doing a sweaty sport, it is quite normal and necessary for you to feel thirsty and drink a lot. The kidneys are responsible for the water balance in your body: controlled by the antidiuretic hormone (ADH or vasopressin), they ensure that sufficient water is absorbed and also excreted again. Diabetes insipidus occurs when there is a lack of ADH or the kidneys do not respond to it. They then excrete very large quantities of very thin urine (up to 30 liters per day, depending on how much they drink). To avoid dehydration, you feel very thirsty and need to drink a lot.
Diabetes insipidus should not be confused with diabetes mellitus. Despite their similar names, the two diseases have completely different causes. What the two have in common are the symptoms of great thirst and frequent urination.
Diabetes insipidus: causes of the hormonal imbalance
Your kidneys have the task of controlling your body’s fluid balance. With the help of the antidiuretic hormone (ADH, vasopressin), these ensure that you absorb or excrete enough water, depending on your needs. The hypothalamus (diencephalon) usually produces ADH, from where it reaches the pituitary gland (hypophysis). There it is stored or released as required. If, for example, you need a lot of fluids on a hot day, your body will use the available water sparingly. To do this, the pituitary gland releases ADH into the blood. The hormone inhibits the kidneys from excreting fluid. If you have drunk a lot, the brain does not release ADH and the kidneys excrete more fluid.
Two forms: Diabetes insipidus centralis and diabetes insipidus renalis
Diabetes insipidus centralis (= central diabetes insipidus): The most common form occurs because the hypothalamus either produces or releases too little ADH. Various diseases can be the cause:
- Tumors on the hypothalamus or pituitary gland
- Inflammations, such as meningitis or encephalitis
- Injuries due to accident or surgery
Around 30 to 50 percent of cases are idiopathic, i.e. no cause can be found despite appropriate examinations. However, a hereditary predisposition seems to have an influence. In some cases, the immune system also attacks the ADH-producing cells and destroys them.
Diabetes insipidus renalis (= renal, or nephrogenic diabetes insipidus): In this case, the kidneys do not respond to the ADH present – the cause of the disorder therefore lies in the kidneys themselves. This form is rare. Possible causes are:
- permanent damage to the kidneys due to a disease
- Highly elevated calcium levels in the blood (hypercalcemia)
- a rare hereditary defect that mothers pass on to their sons. It causes receptors in the kidneys to be defective, to which ADH normally binds.
- Certain medications for depression (lithium salts) can impair kidney function in some cases.
Endocrinology consultation
Diabetes insipidus is a rare disease overall. In the clinics for endocrinology, diabetology and clinical nutrition, we offer a great deal of experience in the diagnosis of diabetes insipidus. In our endocrinology consultation, we carry out the necessary clarifications and, if necessary, additional special tests can be carried out as an inpatient or outpatient in our function room. Experts from the Department of Neuroradiology analyze the imaging results and, thanks to cooperation with specialists in neurosurgery, radiotherapy and oncology, treatment strategies can be determined on an interdisciplinary basis depending on the cause. Patients who require replacement treatment with Desmopressin are trained and cared for by us in order to ensure the optimum dosage.
Symptoms: Increased thirst and strong urge to urinate
Diabetes insipidus often begins very suddenly, but sometimes the symptoms develop gradually. The two main symptoms of diabetes insipidus are that you…
- Excreting large amounts of urine day and night, which is highly diluted (hypotonic) – this can be 3 to 30 liters within 24 hours
- feel very thirsty as a result.
Other symptoms are
- Sleep disturbances because those affected have to drink or go to the toilet several times during the night. Also bedwetting in children.
- Due to the high loss of fluid, the blood salts become unbalanced and the sodium level rises, which can lead to seizures and even coma.
- Irritability, confusion and mental abnormalities due to excess sodium
- dry skin, dry mucous membranes and constipation due to the large loss of fluids.
- Affected infants develop thirst fever. Diarrhea may also occur instead of urine excretion. Growth disorders can also be the result.
- In the case of diabetes insipidus centralis, this growth retardation may also be due to a loss of function of the pituitary gland.
Complications due to diabetes insipidus
The danger of diabetes insipidus lies in possible complications: As you excrete so much fluid, your body does not have enough water available if you do not drink enough. This could even lead to death if left untreated. If you overdose on desmopressin, which is often the drug of choice for diabetes insipidus centralis, you may experience clouding of consciousness with convulsions.
Diabetes insipidus: diagnosis at the USZ
If you are very thirsty and excrete large amounts of urine, we will examine you for diabetes insipidus. First, we will test your urine and blood to check your salt balance and rule out other diseases associated with increased urine excretion, e.g. diabetes mellitus. If the suspicion persists after the initial examinations, additional tests are necessary to confirm the diagnosis. Above all, it is important to distinguish diabetes insipidus from so-called primary polydipsia, in which the increased drinking volume (and subsequent urine excretion) is usually the result of learned increased drinking behavior.
Thirst test with vasopressin or saline infusion test confirm the diagnosis
For the so-called thirst test, you are not allowed to drink anything, while we regularly check your urine production, the amount of salts in your blood and urine and your body weight. After 16 hours – or earlier if appropriate termination criteria are met – the test ends and we inject vasopressin. The diagnosis of diabetes insipidus centralis is confirmed if, in response to vasopressin, the excessive urine excretion stops, the urine becomes more concentrated, the blood pressure rises and your heart beats normally again. The diagnosis of nephrogenic diabetes insipidus is made if excessive urine excretion persists after the injection and the urine remains diluted.
An alternative is the saline infusion test to differentiate between diabetes inspidus centralis and primary polydipsia. One advantage of the test is its shorter duration. At the hospital, the patient is given an infusion of highly concentrated saline solution. The blood values are determined before and after the infusion. Your sodium level is then brought back to normal through fluid intake and infusion.
To determine the cause of the disease in the case of central diabetes insipidus, a magnetic resonance imaging (MRI ) scan of the diencephalon is performed to detect tumors or inflammation.
Central diabetes insipidus: prevention, early detection, prognosis
It is not possible to prevent diabetes insipidus through preventive measures. Early detection is also difficult because the symptoms of the disease usually start suddenly.
The prognosis of diabetes insipidus depends on the underlying disease that causes it: if the underlying inflammation can be cured or the tumor on the hypothalamus can be removed, it may even be completely cured.
If this is not possible, a suitable drug therapy can enable you to lead a normal life. However, an annual check-up by your doctor is necessary.
Central diabetes insipidus: treatment depending on the cause
The first step in treating diabetes insipidus is to stabilize the electrolyte balance and circulation. The next steps depend on the severity and cause of the illness.
If, for example, a tumor has caused the disease, we will try to remove it with surgery, medication or radiotherapy. If a traumatic brain injury or surgery is the cause, diabetes insipidus sometimes resolves itself.
If you suffer from a mild form of central diabetes insipidus in which the body’s own ADH is still partially effective, you may not need therapy. The prerequisite is that you get used to the increased feeling of thirst and also to the fact that you have to urinate more often. Otherwise, therapy with desmopressin (DDAVP) is recommended. This is an artificially produced derivative of the hormone ADH.
Desmopressin works like ADH, but is effective for longer. You can administer it as nasal drops, nasal spray or in tablet form. When dosed correctly, desmopressin is well tolerated and causes hardly any side effects. It is important that you use the medication according to the doctor’s instructions, i.e. with a slowly increasing dosage. Otherwise, water retention (edema) in the tissue and a sodium deficiency may occur in some cases, especially if you continue to drink a lot. Signs of this include headaches, nausea, vomiting, stomach pain or weight gain. In severe cases, there is a risk of edema forming in the brain, which is associated with seizures.
