People with Diabetes insipidus excrete excessive amounts of urine and suffer from increased thirst – just like diabetics, i.e. patients with diabetes mellitus. In contrast to diabetes, diabetes insipidus is based on a hormonally induced disturbance of the water-salt balance. Read here what can cause this disorder, what other symptoms can occur besides increased urination and drinking, and how diabetes insipidus is treated!
Brief overview
Definition: hormonally induced disturbance of the water-electrolyte balance due to excessive excretion of urine. Kidneys are unable to concentrate urine and retain water. Causeseither deficiency of antidiuretic hormone, ADH (diabetes insipidus centralis) or poor kidney response to ADH (diabetes insipidus renalis) SymptomsExcessive urination (polyuria), very dilute urine, excessive thirst and increased fluid intake (polydipsia), possibly diabetes mellitus, often also simple diabetes. neurological symptoms (such as confusion, weakness) Diagnostics: blood and urine tests, thirst test treatmentDepending on the form and severity of the disease, medication (desmopressin as an ADH substitute, if necessary) may be necessary. Elimination of the cause. Sometimes, in addition to treating the causes, it is sufficient to salt-. Low protein diet as well as adequate fluid intake. Sometimes, in addition to the cause treatment, a saline-. Low protein diet as well as adequate fluid intake.
Diabetes insipidus: Definition
Diabetes insipidus ("water urine dysfunction") is a rare disease caused by a hormonal disorder. This unbalances the water-electrolyte balance (water-salt balance): the kidneys are unable to concentrate urine and retain water in the body. As a result, sufferers excrete large amounts of dilute urine (up to 20 liters daily!).
Forms of the disease
The hormone disorder behind diabetes insipidus affects the Antidiuretic hormone (ADH). That too Vasopressin The hormone is produced in the hypothalamus, a part of the diencephalon. However, it is stored and released as needed by the neighboring pituitary gland (hypophysis).
ADH is involved in the regulation of water balance. When there is a lack of water in the body, the pituitary gland releases ADH into the blood. It causes the kidneys to concentrate the urine more – that is, to retain more water.
In diabetes insipidus, this regulatory mechanism is disturbed. Depending on the exact location of the disorder, physicians distinguish between the following forms of the disease:
Diabetes insipidus centralis: Here, a disturbance in the area of hypothalamus resp. Pituitary gland has an ADH deficiency – the hormone is completely absent or present in insufficient amounts. In both cases, the body cannot (sufficiently) signal the kidneys to retain water in the body. Central diabetes insipidus is also called "diabetes insipidus neurohormonalis" called. diabetes insipidus renalis: In renal diabetes insipidus, there is sufficient ADH but the kidneys do not respond or do not respond sufficiently to it. So there is an ADH resistance. This form of the disease is also called nephrogenic diabetes insipidus ("nephrogenic" stands for "originating from the kidney").
Diabetes mellitus: similarities and differences
Despite a different disease mechanism, diabetes insipidus and diabetes mellitus (diabetes) have one thing in common, which is the common name "diabetes" reflects. The term means "flow and indicates pathologically increased urine excretion in both diseases to.
As mentioned, diabetes insipidus is caused by the inability of the kidney to concentrate urine. This is diluted – hence the name diabetes insipidus .
In contrast, the frequent urination in diabetes mellitus is due to the abnormally elevated blood glucose level. The body tries to get rid of the excess sugar (glucose) through the urine. And because sugar physically binds water, a lot of water is also lost: the patient therefore excretes large amounts of urine containing sugar – hence the name"honeyed flow".
Diabetes insipidus: symptoms
The leading symptoms of diabetes insipidus are:
Polyuria: excessive urine output of more than 2.5 liters in 24 hours (sometimes diarrhea in infants instead of polyuria). The increased urination is particularly noticeable at night – nighttime urination (nocturia) repeatedly wakes the affected person up. Polydipsia: Increased thirst and fluid intake (often ice cold water is preferred) Asthenuria: inability of the kidney to concentrate the urine, which is why it is diluted (measurable as decreased osmolality = decreased concentration of dissolved particles)
If patients cannot compensate for increased water loss by drinking more, the body becomes dehydrated. Doctors refer to this as Dehydration (or dehydration).
Sometimes diabetes insipidus also causes neurological symptoms to: The increased urine output increases the sodium level in the blood (hypernatremia). This may be reflected, for example, in confusion, muscle weakness and lethargy. Lethargy is a disorder of consciousness with drowsiness and physical and mental slowing down (sluggishness).
In some patients, diabetes insipidus is the result of another disease (see below: Causes). Then come Symptoms of the underlying disease added.
Diabetes insipidus: diagnostics
In conversation with the patient (or. in the case of children with the parents), the doctor first ascertains the Medical history (anamnesis). In addition, he inquires, among other things, about the occurring symptoms and any known underlying diseases. A common Physical examination is also part of the routine when someone comes to the doctor with unexplained symptoms such as increased urination.
What to do with hay fever? How pollen allergy sufferers can get through the allergy season without worrying and enjoy nature. In diabetes insipidus, increased values for sodium can be. Detect other salts (electrolytes). Sodium levels are particularly markedly elevated in patients who do not (cannot) drink enough fluids to compensate for water loss. Urine: Urine over 24 hours is collected and then analyzed. In diabetes insipidus, it is diluted (lowered concentration of dissolved particles = lowered osmolality). The specific urine weight is reduced, the sugar content in the urine is normal (distinguishing feature from diabetes mellitus – where the sugar in the urine is increased).
Thirst test
The suspected diagnosis of diabetes insipidus can be compared with a Thirst test (water deprivation test) confirm. The exact test procedure may vary. Basically, however, it works as follows:
The patient may be allowed to drink for several hours (z.B. 12 hours) do not drink anything. During this time, he is continuously monitored by a physician in case he becomes dangerously dehydrated. Various parameters are measured regularly, such as the amount of urine passed, the amount of dissolved particles (osmolality) in the urine and blood, and the patient's body weight.
Despite lack of fluid intake, patients with diabetes insipidus continue to excrete urine, and this urine is dilute without change (unchanged urine osmolality), while blood serum osmolality increases. In healthy individuals, on the other hand, the amount of urine would decrease and the urine osmolality would increase during the thirst test.
The test is stopped either after the scheduled duration or earlier if the patient's blood prere drops, heart rate increases or body weight decreases by more than five percent.
Differentiation between central and renal diabetes insipidus
If the measurements in the thirst test confirm diabetes insipidus, the physician can find out which form of the disease is present by administering a hormone preparation before stopping the test:
For this purpose, he injects the patient with ADH, i.e. vasopressin (or its synthetic derivative desmopressin, which is alternatively available as a nasal spray). Subsequently, the discharged urine is analyzed again:
– Diabetes insipidus centralis : Vasopressin administration decreases urine excretion and the urine is less dilute – recognizable by an increase in urine osmolality: it is 50 to 100 percent if the disease is due to total ADH deficiency, and still 15 to 45 percent in case of partial ADH deficiency (lowered ADH level). – Diabetes insipidus renalis : Despite vasopressin intake, excessive urine excretion continues, and the urine is only slightly less dilute (slight increase in urine osmolality) – after all, the problem here is not a lack of hormone, but a lack of or inadequate response of the kidneys to the hormone.
It would also be possible to distinguish between the two forms by direct measurement of ADH in the blood, at the end of the thirst test (before vasopressin injection). In diabetes insipidus centralis, the ADH level would be low; in diabetes insipidus renalis, it would be appropriately elevated. However, this measurement is difficult. Does not belong to the routine program. In addition, the thirst test provides sufficiently accurate results.
Differential diagnosis psychogenic polydipsia
When someone drinks and excretes many liters of fluid per day, it is not always due to a form of diabetes. Thirst and subsequently urination may also be increased above normal as a result of a mental illness such as schizophrenia.
When clarifying a suspected diabetes insipidus, the physician must exclude such psychogenic polydipsia, which is not always easy to do. However, there are some indications. For example, people with psychogenic polydipsia do not suffer from nocturnal urination (nocturia) that repeatedly rouses them from sleep – unlike people with diabetes insipidus. Hair loss is for men. Women equally troublesome. More about the causes and treatment options for hereditary hair loss.
Diabetes insipidus: treatment
Treatment of diabetes insipidus depends on the form, cause, and severity of the condition. It aims to reduce urine output to the point where the patient can lead a normal life and is no longer awakened at night by an excessive urge to urinate.
Therapy of diabetes insipidus centralis
Diabetes insipidus centralis is usually treated with a hormone replacement necessary – the missing hormone ADH must be replaced by medication, namely by regular administration of desmopressin. This artificial derivative of antidiuretic hormone acts in the same way as its natural counterpart, but has a longer duration of action. It can be applied in different ways. Many patients administer desmopressin to themselves as a nasal spray. The active ingredient is also available as a tablet and as an injection under the skin or into a vein. The dosage is adjusted individually in all cases.
Desmopressin is also often used to treat children (and adults) who wet the bed at night (bedwetting, enuresis) – it suppresses the urge to urinate at night.
In addition to or as an alternative to desmopressin, diabetes insipidus centralis may still be treated with other medications can be useful:
– Thiazide diuretics : These are dehydrating drugs that paradoxically can reduce the amount of urine in patients with diabetes insipidus centralis (and diabetes insipidus renalis). – ADH-releasing drugs : They increase ADH production and are thus suitable for patients with partial ADH deficiency (i.e., when the body can still provide small amounts of ADH). These agents include, for example, the blood sugar-lowering agent chlorpropamide and the epilepsy drug carbamazepine. They can be combined with thiazide diuretics. – Prostaglandin inhibitors: drugs such as indomethacin (an anti-inflammatory and pain reliever in the NSAID group) can reduce urine output, although usually only slightly. However, the effect can be increased if the patient also takes a thiazide diuretic and eats a low-sodium diet.
Regardless of whether the ADH deficiency is complete or partial, if possible in cases of central diabetes insipidus, the patient should always also Cause eliminated. For example, a brain tumor that causes ADH deficiency can often be surgically removed.
Therapy of diabetes insipidus renalis
The treatment of this form of diabetes insipidus is more difficult. It consists of several components:
– Drinking an adequate amount of water – Low salt and low protein diet – If possible, eliminating the cause of the disease
If diabetes insipidus symptoms persist despite these measures, the doctor prescribes medications that reduce the amount of urine. Agents that are partly given in diabetes insipidus centralis come into question: dehydrating drugs (thiazide diuretics or the potassium-saving diuretic amiloride) or NSAIDs (such as indometacin).
Sufficient drinking is extremely important in diabetes insipidus renalis: even several hours without fluid intake can cause severe dehydration!
Diabetes insipidus: causes
Both forms of the disease – central and renal diabetes insipidus – can be hereditary or acquired his (for example, due to various diseases). In addition, there are cases in which no cause of the disease can be found. They are called"idiopathic" describes.
Causes of diabetes insipidus centralis
As Primary Diabetes insipidus centralis is the name given by physicians to a hereditary variant of the disease. Often a mutation of the vasopressin gene on chromosome 20 is behind it.
A secondary Diabetes insipidus centralis is acquired. It can have triggers including the following:
– Cranial injuries (v.a. tumors above or inside the saddle of the skull (a saddle-shaped part of the skull bone, in the depression of which the pituitary gland is located) – nodular tie formations (granulomas), malformations (such as aneurysms) of the arteries supplying the brain – infectious inflammation of the brain or meninges (encephalitis, meningitis) – total removal of the pituitary gland (hypophysectomy), z.B. in the case of a pituitary tumor
Diabetes insipidus centralis may also develop transiently in the second half of pregnancy: The placenta may produce an enzyme (vasopressinase) that provides for increased breakdown of ADH. The hormone level can then drop so much that the kidneys can no longer retain sufficient water in the body.
Causes of diabetes insipidus renalis
In some patients, diabetes insipidus renalis Hereditary. In most cases, the cause is a gene mutation on the X chromosome, i.e. the female sex chromosome. Affected males always develop renal diabetes insipidus because they have only one X chromosome. In women with their two X chromosomes, on the other hand, the mutation can have different effects: Some women have no symptoms, others develop polydipsia and polyuria to varying degrees, and still others develop diabetes insipidus renalis with the same severity as men with this mutation.
More rarely, hereditary diabetes insipidus renalis is due to a gene mutation on a different chromosome (not a sex chromosome, but a non-sex-determining autosome). This mutation can then lead to the onset of the disease regardless of gender.
Acquired forms Of diabetes insipidus renalis are the result of diseases or medications that affect the kidneys. Examples are:
– Polycystic kidney disease: hereditary disease in which numerous fluid-filled cavities (cysts) form in the kidneys – at the expense of intact kidney tie. – Renal pelvic inflammation – Sickle cell anemia: hereditary disease in which sickle-shaped instead of disc-shaped red blood cells (erythrocytes) are formed. These can clog vessels. Thus damaging the kidneys, among other things. – Amyloidosis: rare disease with abnormally folded proteins (proteins consist of long chains of amino acids that are normally folded in a certain way). The abnormal proteins can be deposited in the kidneys, among other places, and thus damage them. – Sjogren's syndrome – certain cancers (such as myeloma, sarcoma) – various drugs: v.a. Lithium (for mental disorders), but also others such as demeclocycline and ofloxacin (antibiotics), amphotericin B (antifungals), dexamethasone (a cortisone), ifosfamide (cancer drug), orlistat (for obesity)
Diabetes insipidus: prognosis
In most cases, diabetes insipidus can be easily treated. Acquired forms of the disease are sometimes even curable – provided the cause (z.B. a brain tumor) can be eliminated. If not, however, with appropriate therapy and good medical care, affected individuals can usually lead normal lives.
There is no cure for congenital (hereditary) diabetes insipidus. With the right treatment and care, however, the disease can be kept under control, so that a normal life is generally possible. However, early treatment is important! If, for example, babies are born with hereditary diabetes insipidus renalis, but this is not recognized and treated immediately, there is a risk of permanent brain damage with reduced intelligence.