Diabetes insipidus
Encyclopedia
Diabetes insipidus is a condition
characterized by excessive thirst
and excretion of large amounts of severely diluted urine
, with reduction of fluid intake having no effect on the concentration of the urine. There are several different types of DI, each with a different cause. The most common type in humans is central DI, caused by a deficiency of arginine vasopressin
(AVP), also known as antidiuretic hormone (ADH). The second common type of DI is nephrogenic diabetes insipidus
, which is caused by an insensitivity of the kidney
s to ADH. It can also be an iatrogenic artifact of drug use.
Although they have a common name, diabetes mellitus
and diabetes insipidus are two entirely separate conditions with unrelated mechanisms. Both cause large amounts of urine to be produced (polyuria
), and the term diabetes is derived from the Greek name for this symptom. However, diabetes insipidus is either a problem with the production of antidiuretic hormone (cranial diabetes insipidus) or kidney's response to antidiuretic hormone (nephrogenic diabetes insipidus), whereas diabetes mellitus causes polyuria via a process called osmotic diuresis
, due to the high blood sugar leaking into the urine and taking excess water along with it.
The incidence of diabetes insipidus in the general population is 3 in 100,000. The name refers to the inability to retain fluid (diabetes = passing [water] through) and the lack of sugar in the urine (insipidus = tasteless).
, with the distinction that the urine does not contain glucose and there is no hyperglycemia
(elevated blood glucose). Blurred vision is a rarity. Signs of dehydration
may also appear in some individuals since the body cannot conserve much (if any) of the water it takes in.
The extreme urination continues throughout the day and the night. In children, DI can interfere with appetite, eating, weight gain, and growth
as well. They may present with fever
, vomiting
, or diarrhea
. Adults with untreated DI may remain healthy for decades as long as enough water is consumed to offset the urinary losses. However, there is a continuous risk of dehydration
and loss of potassium.
levels, and calcium
levels need to be tested. Measurement of blood electrolyte
s can reveal a high sodium
level (hypernatremia
as dehydration
develops). Urinalysis
demonstrates a dilute urine with a low specific gravity
. Urine osmolarity and electrolyte levels are typically low.
A fluid deprivation test
helps determine whether DI is caused by:
This test measures changes in body weight, urine output, and urine composition when fluids are withheld and as dehydration occurs. The body's normal response to dehydration is to concentrate urine and conserve water, so urine becomes more concentrated and urination becomes less frequent. Those with DI continue to urinate large amounts of dilute urine in spite of not drinking any fluids. In primary polydipsia, the urine osmolality should increase and stabilize at above 280 Osm/kg with fluid restriction, while a stabilization at a lower level indicates diabetes insipidus. Stabilization in this test means, more specifically, when the hourly increase in osmolality is less than 30 Osm/kg per hour for at least 3 hours. Sometimes measuring blood levels of ADH during this test is also necessary, but is more time consuming to perform.
To distinguish between the main forms, desmopressin
stimulation is also used; desmopressin can be taken by injection, a nasal spray, or a tablet. While taking desmopressin, a patient should drink fluids or water only when thirsty and not at other times, as this can lead to sudden fluid accumulation in the central nervous system. If desmopressin reduces urine output and increases osmolarity, the pituitary production of ADH is deficient, and the kidney responds normally. If the DI is due to renal pathology, desmopressin does not change either urine output or osmolarity.
If central DI is suspected, testing of other hormones of the pituitary, as well as magnetic resonance imaging
(MRI), is necessary to discover if a disease process (such as a prolactinoma
, or histiocytosis
, syphilis
, tuberculosis
or other tumor
or granuloma
) is affecting pituitary function. Most people with this form have either experienced past head trauma or have stopped ADH production for an unknown reason.
Habit drinking (in its severest form termed psychogenic polydipsia
) is the most common imitator of diabetes insipidus at all ages. While many adult cases in the medical literature are associated with mental disorders, most patients with habit polydipsia have no other detectable disease. The distinction is made during the water deprivation test, as some degree of urinary concentration above isosmolar is usually obtained before the patient becomes dehydrated.
is a complex mechanism that balances the body's requirements for blood pressure
and the main electrolytes sodium
and potassium
. In general, electrolyte regulation precedes volume regulation. When the volume is severely depleted, however, the body will retain water at the expense of deranging electrolyte levels.
The regulation of urine production occurs in the hypothalamus
, which produces ADH
in the supraoptic
and paraventricular
nuclei. After synthesis, the hormone is transported in neurosecretory granules down the axon of the hypothalamic neuron to the posterior lobe of the pituitary gland
where it is stored for later release. In addition, the hypothalamus regulates the sensation of thirst in the ventromedial nucleus
by sensing increases in serum osmolarity and relaying this information to the cortex
.
The main effector organ for fluid
homeostasis is the kidney
. ADH acts by increasing water permeability in the collecting ducts and distal convoluted tubules, specifically it acts on proteins called aquaporin
s and more specifically aquaporin 2 in the following cascade; ADH (aka argenine vasopressin-AVP) produced in the hypothalmus and stored in the posterior pituitary. When released, ADH binds to V2 G-protein coupled receptors within the distal convoluted tubules, increasing cyclic AMP, which couples with protein kinase A stimulating transcription of the aquaporin 2 channel stored in the cytoplasm
of the distal convoluted tubules and collecting ducts into the apical membrane. These transcripted channels allow water into the collecting duct cells. The increase in permeability allows for reabsorption of water into the bloodstream, thus concentrating the urine.
Hereditary forms of diabetes insipidus account for less than 10% of the cases of diabetes insipidus seen in clinical practice.
production in the brain.
. During pregnancy, all women produce vasopressinase in the placenta
, which breaks down ADH. Gestational DI is thought to occur with excessive vasopressinase production.
Most cases of gestational DI can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and desmopressin should not be used.
Diabetes insipidus is also associated with some serious diseases of pregnancy, including pre-eclampsia
, HELLP Syndrome
and acute fatty liver of pregnancy
. These cause diabetes insipidus by activating hepatic vasopressinase. It is important to consider these diseases if a woman presents with diabetes insipidus in pregnancy, because their treatments require delivery of the baby before the disease will improve. Failure to treat these diseases promptly can lead to maternal or perinatal mortality.
. Carbamazepine
, an anti-convulsive medication, has also had some success in this type of DI. Also gestational DI tends to abate on its own 4 to 6 weeks following labour, though some women may develop it again in subsequent pregnancies. In dipsogenic DI, desmopressin is not usually an option.
Desmopressin will be ineffective in nephrogenic DI. Instead, the diuretic
hydrochlorothiazide
(a thiazide diuretic) or indomethacin can improve nephrogenic diabetes insipidus. Thiazide diuretics are sometimes combined with amiloride
to prevent hypokalemia
. It seems paradoxical to treat an extreme diuresis with a diuretic but the thiazide diuretics will decrease distal convoluted tubule reabsorption of sodium and water, thereby causing diuresis. This decreases plasma volume, thus lowering GFR and enhancing the absorption of sodium and water in the proximal nephron. Less fluid reaches the distal nephron so overall fluid conservation is obtained.
Lithium-induced nephrogenic DI may be effectively managed with the administration of amiloride, a potassium-sparing diuretic often used in conjunction with thiazide or loop diuretics. Clinicians have been aware of lithium toxicity for many years and traditionally have administered thiazide diuretics for lithium-induced polyuria and nephrogenic diabetes insipidus. However, recently amiloride has been shown to be a successful treatment for this condition.
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
characterized by excessive thirst
Polydipsia
Polydipsia is a medical symptom in which the patient displays excessive thirst. The word derives from the Greek πολυδιψία, which is derived from πολύς + δίψα...
and excretion of large amounts of severely diluted urine
Polyuria
Polyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
, with reduction of fluid intake having no effect on the concentration of the urine. There are several different types of DI, each with a different cause. The most common type in humans is central DI, caused by a deficiency of arginine vasopressin
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
(AVP), also known as antidiuretic hormone (ADH). The second common type of DI is nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus is a form of diabetes insipidus due primarily to pathology of the kidney. This is in contrast to central/neurogenic diabetes insipidus, which is caused by insufficient levels of antidiuretic hormone /Argenine Vasopressin...
, which is caused by an insensitivity of the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
s to ADH. It can also be an iatrogenic artifact of drug use.
Although they have a common name, diabetes mellitus
Diabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
and diabetes insipidus are two entirely separate conditions with unrelated mechanisms. Both cause large amounts of urine to be produced (polyuria
Polyuria
Polyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
), and the term diabetes is derived from the Greek name for this symptom. However, diabetes insipidus is either a problem with the production of antidiuretic hormone (cranial diabetes insipidus) or kidney's response to antidiuretic hormone (nephrogenic diabetes insipidus), whereas diabetes mellitus causes polyuria via a process called osmotic diuresis
Osmotic diuresis
Osmotic diuresis is increased urination caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed...
, due to the high blood sugar leaking into the urine and taking excess water along with it.
The incidence of diabetes insipidus in the general population is 3 in 100,000. The name refers to the inability to retain fluid (diabetes = passing [water] through) and the lack of sugar in the urine (insipidus = tasteless).
Signs and symptoms
Excessive urination and extreme thirst (especially for cold water and sometimes ice or ice water) are typical for DI. Symptoms of diabetes insipidus are quite similar to those of untreated diabetes mellitusDiabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
, with the distinction that the urine does not contain glucose and there is no hyperglycemia
Hyperglycemia
Hyperglycemia or Hyperglycæmia, or high blood sugar, is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a glucose level higher than 13.5mmol/l , but symptoms may not start to become noticeable until even higher values such as 15-20 mmol/l...
(elevated blood glucose). Blurred vision is a rarity. Signs of dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
may also appear in some individuals since the body cannot conserve much (if any) of the water it takes in.
The extreme urination continues throughout the day and the night. In children, DI can interfere with appetite, eating, weight gain, and growth
Human development (biology)
Human development is the process of growing to maturity. In biological terms, this entails growth from a one-celled zygote to an adult human being.- Biological development:...
as well. They may present with fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, or diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
. Adults with untreated DI may remain healthy for decades as long as enough water is consumed to offset the urinary losses. However, there is a continuous risk of dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
and loss of potassium.
Diagnosis
In order to distinguish DI from other causes of excess urination, blood glucose levels, bicarbonateBicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...
levels, and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
levels need to be tested. Measurement of blood electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
s can reveal a high sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
level (hypernatremia
Hypernatremia
Hypernatremia or hypernatraemia is an electrolyte disturbance that is defined by an elevated sodium level in the blood. Hypernatremia is generally not caused by an excess of sodium, but rather by a relative deficit of free water in the body...
as dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
develops). Urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
demonstrates a dilute urine with a low specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
. Urine osmolarity and electrolyte levels are typically low.
A fluid deprivation test
Fluid deprivation test
A fluid or water deprivation test is a medical test which can be used to determine whether the patient has diabetes insipidus as opposed to other causes of polydipsia...
helps determine whether DI is caused by:
- excessive intake of fluid (primary polydipsia)
- a defect in ADH production
- a defect in the kidneys' response to ADH
This test measures changes in body weight, urine output, and urine composition when fluids are withheld and as dehydration occurs. The body's normal response to dehydration is to concentrate urine and conserve water, so urine becomes more concentrated and urination becomes less frequent. Those with DI continue to urinate large amounts of dilute urine in spite of not drinking any fluids. In primary polydipsia, the urine osmolality should increase and stabilize at above 280 Osm/kg with fluid restriction, while a stabilization at a lower level indicates diabetes insipidus. Stabilization in this test means, more specifically, when the hourly increase in osmolality is less than 30 Osm/kg per hour for at least 3 hours. Sometimes measuring blood levels of ADH during this test is also necessary, but is more time consuming to perform.
To distinguish between the main forms, desmopressin
Desmopressin
Desmopressin is a synthetic replacement for vasopressin, the hormone that reduces urine production. It may be taken nasally, intravenously, or as a tablet...
stimulation is also used; desmopressin can be taken by injection, a nasal spray, or a tablet. While taking desmopressin, a patient should drink fluids or water only when thirsty and not at other times, as this can lead to sudden fluid accumulation in the central nervous system. If desmopressin reduces urine output and increases osmolarity, the pituitary production of ADH is deficient, and the kidney responds normally. If the DI is due to renal pathology, desmopressin does not change either urine output or osmolarity.
If central DI is suspected, testing of other hormones of the pituitary, as well as magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
(MRI), is necessary to discover if a disease process (such as a prolactinoma
Prolactinoma
A prolactinoma is a benign tumor of the pituitary gland that produces a hormone called prolactin. It is the most common type of pituitary tumor...
, or histiocytosis
Histiocytosis
In medicine, histiocytosis refers to an excessive number of histiocytes, , and is typically used to refer to a group of rare diseases which share this as a characteristic...
, syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
, tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
or other tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
or granuloma
Granuloma
Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
) is affecting pituitary function. Most people with this form have either experienced past head trauma or have stopped ADH production for an unknown reason.
Habit drinking (in its severest form termed psychogenic polydipsia
Psychogenic polydipsia
Primary polydipsia or psychogenic polydipsia is a special form of polydipsia. It is usually associated with a patient's increasing fluid intake due to the sensation of having a dry mouth....
) is the most common imitator of diabetes insipidus at all ages. While many adult cases in the medical literature are associated with mental disorders, most patients with habit polydipsia have no other detectable disease. The distinction is made during the water deprivation test, as some degree of urinary concentration above isosmolar is usually obtained before the patient becomes dehydrated.
Pathophysiology
Electrolyte and volume homeostasisHomeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
is a complex mechanism that balances the body's requirements for blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
and the main electrolytes sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
and potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
. In general, electrolyte regulation precedes volume regulation. When the volume is severely depleted, however, the body will retain water at the expense of deranging electrolyte levels.
The regulation of urine production occurs in the hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
, which produces ADH
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
in the supraoptic
Supraoptic nucleus
The supraoptic nucleus is a nucleus of magnocellular neurosecretory cells in the hypothalamus of the mammalian brain. The nucleus is situated at the base of the brain, adjacent to the optic chiasm...
and paraventricular
Paraventricular nucleus
The paraventricular nucleus is a neuronal nucleus in the hypothalamus. It contains multiple subpopulations of neurons that are activated by a variety of stressful and/or physiological changes. Many PVN neurons project directly to the posterior pituitary where they release oxytocin or vasopressin...
nuclei. After synthesis, the hormone is transported in neurosecretory granules down the axon of the hypothalamic neuron to the posterior lobe of the pituitary gland
Pituitary gland
In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...
where it is stored for later release. In addition, the hypothalamus regulates the sensation of thirst in the ventromedial nucleus
Ventromedial nucleus
The ventromedial nucleus is a nucleus of the hypothalamus.-Division:It has four subdivisions:* anterior * dorsomedial * ventrolateral * central ....
by sensing increases in serum osmolarity and relaying this information to the cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
.
The main effector organ for fluid
Body water
In medicine, body water is the water content of the human body. A significant fraction of the human body is water. Arthur Guyton 's Textbook of Medical Physiology states that "the total amount of water in a man of average weight is approximately 40 litres, averaging 57 percent of his total body...
homeostasis is the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
. ADH acts by increasing water permeability in the collecting ducts and distal convoluted tubules, specifically it acts on proteins called aquaporin
Aquaporin
Aquaporins are proteins embedded in the cell membrane that regulate the flow of water.Aquaporins are integral membrane proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells....
s and more specifically aquaporin 2 in the following cascade; ADH (aka argenine vasopressin-AVP) produced in the hypothalmus and stored in the posterior pituitary. When released, ADH binds to V2 G-protein coupled receptors within the distal convoluted tubules, increasing cyclic AMP, which couples with protein kinase A stimulating transcription of the aquaporin 2 channel stored in the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
of the distal convoluted tubules and collecting ducts into the apical membrane. These transcripted channels allow water into the collecting duct cells. The increase in permeability allows for reabsorption of water into the bloodstream, thus concentrating the urine.
Hereditary forms of diabetes insipidus account for less than 10% of the cases of diabetes insipidus seen in clinical practice.
Neurogenic
Neurogenic diabetes insipidus, more commonly known as central diabetes insipidus, is due to a lack of vasopressinVasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
production in the brain.
Nephrogenic
Nephrogenic diabetes insipidus is due to the inability of the kidney to respond normally to vasopressin.Dipsogenic
Dipsogenic DI is due to a defect or damage to the thirst mechanism, which is located in the hypothalamus. This defect results in an abnormal increase in thirst and fluid intake that suppresses vasopressin secretion and increases urine output. Desmopressin is ineffective, and can lead to fluid overload as the thirst remains.Gestational
Gestational DI only occurs during pregnancyPregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. During pregnancy, all women produce vasopressinase in the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
, which breaks down ADH. Gestational DI is thought to occur with excessive vasopressinase production.
Most cases of gestational DI can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and desmopressin should not be used.
Diabetes insipidus is also associated with some serious diseases of pregnancy, including pre-eclampsia
Pre-eclampsia
Pre-eclampsia or preeclampsia is a medical condition in which hypertension arises in pregnancy in association with significant amounts of protein in the urine....
, HELLP Syndrome
HELLP syndrome
HELLP syndrome is a life-threatening obstetric complication usually considered to be a variant of pre-eclampsia. Both conditions usually occur during the later stages of pregnancy, or sometimes after childbirth.HELLP is an abbreviation of the main findings:...
and acute fatty liver of pregnancy
Acute fatty liver of pregnancy
Acute fatty liver of pregnancy is a rare life-threatening complication of pregnancy that occurs in the third trimester or the immediate period after delivery. It is thought to be caused by a disordered metabolism of fatty acids by mitochondria in the mother, caused by deficiency in the LCHAD enzyme...
. These cause diabetes insipidus by activating hepatic vasopressinase. It is important to consider these diseases if a woman presents with diabetes insipidus in pregnancy, because their treatments require delivery of the baby before the disease will improve. Failure to treat these diseases promptly can lead to maternal or perinatal mortality.
Treatment
Central DI and gestational DI respond to desmopressinDesmopressin
Desmopressin is a synthetic replacement for vasopressin, the hormone that reduces urine production. It may be taken nasally, intravenously, or as a tablet...
. Carbamazepine
Carbamazepine
Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...
, an anti-convulsive medication, has also had some success in this type of DI. Also gestational DI tends to abate on its own 4 to 6 weeks following labour, though some women may develop it again in subsequent pregnancies. In dipsogenic DI, desmopressin is not usually an option.
Desmopressin will be ineffective in nephrogenic DI. Instead, the diuretic
Diuretic
A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
hydrochlorothiazide
Hydrochlorothiazide
Hydrochlorothiazide, abbreviated HCTZ, HCT, or HZT, is a first-line diuretic drug of the thiazide class that acts by inhibiting the kidneys' ability to retain water. This reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms, is...
(a thiazide diuretic) or indomethacin can improve nephrogenic diabetes insipidus. Thiazide diuretics are sometimes combined with amiloride
Amiloride
Amiloride is a potassium-sparing diuretic, first approved for use in 1967 , used in the management of hypertension and congestive heart failure. Amiloride was also tested as treatment of cystic fibrosis, but it was revealed inefficient in vivo due to it's short time of action, therefore...
to prevent hypokalemia
Hypokalemia
Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
. It seems paradoxical to treat an extreme diuresis with a diuretic but the thiazide diuretics will decrease distal convoluted tubule reabsorption of sodium and water, thereby causing diuresis. This decreases plasma volume, thus lowering GFR and enhancing the absorption of sodium and water in the proximal nephron. Less fluid reaches the distal nephron so overall fluid conservation is obtained.
Lithium-induced nephrogenic DI may be effectively managed with the administration of amiloride, a potassium-sparing diuretic often used in conjunction with thiazide or loop diuretics. Clinicians have been aware of lithium toxicity for many years and traditionally have administered thiazide diuretics for lithium-induced polyuria and nephrogenic diabetes insipidus. However, recently amiloride has been shown to be a successful treatment for this condition.
Further reading
- The public domainPublic domainWorks are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...
document "Diabetes Insipidus", NIH Publication No. 01-4620, December 2000.