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The incidence of SIADH rises with increasing age. Residents of nursing homes are at highest risk.
In a study of 1,034 symptomatic adults, Sheehan syndrome was found to be the sixth most frequent etiology of growth hormone deficiency, being responsible for 3.1% of cases (versus 53.9% due to a pituitary tumor).
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by excessive unsuppressible release of antidiuretic hormone (ADH) either from the posterior pituitary gland, or an abnormal non-pituitary source. Unsuppressed ADH causes an unrelenting increase in solute-free water being returned by the tubules of the kidney to the venous circulation.
ADH is derived from a preprohormone precursor that is synthesized in cells in the hypothalamus and stored in vesicles in the posterior pituitary. "Appropriate" ADH secretion is regulated by osmoreceptors on the hypothalamic cells that synthesize and store ADH: plasma hypertonicity activates these receptors, ADH is released into the blood stream, the kidney increases solute-free water return to the circulation, and the hypertonicity is alleviated. "Inappropriate" ADH secretion causes a "unrelenting increase" in solute-free water ("free water") absorption by the kidneys, with two consequences. First, in the extracellular fluid (ECF) space, there is a dilution of blood solutes, causing hypoosmolality, including a low sodium concentration - hyponatremia. Then virtually simultaneously, in the intracellular space, cells swell, i.e. intracellular volume increases. Swelling of brain cells causes various neurological abnormalities which in severe or acute cases can result in convulsions, coma, and death.
The causes of SIADH are grouped into six categories: 1) central nervous system diseases that directly stimulate the hypothalamus, the site of control of ADH secretion; 2) various cancers that synthesize and secrete ectopic ADH; 3) various pulmonary diseases; 4) numerous (at least seventeen) drugs that chemically stimulate the hypothalamus; 5) inherited mutations that cause aquaporins always to be "turned on"; and 6) miscellaneous largely transient conditions.
Potential treatments of SIADH include restriction of fluid intake, correction of an identifiable reversible underlying cause, and/or medication which promotes solute-free water excretion by the kidney. The presence of cerebral edema may necessitate intravenous isotonic or hypertonic saline administration.
SIADH was originally described in 1957 in two people with small-cell carcinoma of the lung.
Dipsogenic DI or primary polydipsia results from excessive intake of fluids as opposed to deficiency of arginine vasopressin. It may be due to a defect or damage to the thirst mechanism, located in the hypothalamus; or due to mental illness. Treatment with DDAVP may lead to water intoxication.
Nephrogenic diabetes insipidus is due to the inability of the kidney to respond normally to vasopressin.
In the developed world it is a rare complication of pregnancy, usually occurring after excessive blood loss. The presence of disseminated intravascular coagulation (i.e., in amniotic fluid embolism or HELLP syndrome) also appears to be a factor in its development.
This condition has several known causes, dietary and genetic. Dietary causes include the chronic excessive ingestion of licorice. Licorice inhibits the 11-beta hydroxysteroid dehydrogenase type II () enzyme resulting in inappropriate stimulation of the mineralocorticoid receptor by cortisol.
Genetic causes include Liddle's syndrome.
Genetically, there is a postzygotic mutation (spontaneous mutation) of the gene GNAS, on the long (q) arm of chromosome 20 at position 13.3, which is involved in G-protein signaling. This mutation, which occurs only in the mosaic state, leads to constitutive receptor signaling and inappropriate production of excess cAMP.
The mutation that causes McCune–Albright syndrome arises very early during embryogenesis. It is not passed down from parent to child. There are no known risk factors for acquiring McCune–Albright syndrome, and no exposures during pregnancy that are known to either cause or prevent the mutation from occurring.
This condition is characterized by hypertension, kaliuresis and reduced plasma renin.
Children with PSS have extremely low levels of growth hormone. These children possibly have a problem with growth hormone inhibiting hormone (GHIH) or growth hormone releasing hormone (GHRH). The children could either be unresponsive to GHRH, or too sensitive to GHIH.
Children who have PSS exhibit signs of failure to thrive. Even though they appear to be receiving adequate nutrition, they do not grow and develop normally compared to other children of their age.
An environment of constant and extreme stress causes PSS. Stress releases hormones in the body such as epinephrine and norepinephrine engage what is known as the 'fight or flight' response. The heart speeds up and the body diverts resources away from processes that are not immediately important; in PSS, the production of growth hormone (GH) is thus affected. As well as lacking growth hormone, children with PSS exhibit gastrointestinal problems due to the large amounts of epinephrine and norepinephrine, resulting in their bodies lacking proper digestion of nutrients and further affecting development.
While the cure for PSS is questionable, some studies show that placing the child affected with the disease in a foster or group home increases growth rate and socialization skills.
Nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD) is a rare and serious syndrome that involves fibrosis of skin, joints, eyes, and internal organs. The first cases were identified in 1997 and its cause is not fully understood. However, evidence suggests NSF is associated with exposure to gadolinium (with gadolinium-based MRI contrast agents being frequently used as contrast agents for magnetic resonance imaging (MRI)) in patients with severe kidney failure. Epidemiological studies suggest that the incidence of NSF is unrelated to gender, ethnicity, or age and it is not thought to have a genetic basis. A registry for NSF has identified about 335 cases as of 2011.
Most patients with NSF have undergone hemodialysis for kidney failure, some have never undergone dialysis and others have received only peritoneal dialysis. Many people with NSF have taken immunosuppressive medications and have other diseases, such as hepatitis C. Four of the seven gadolinium contrast agents approved by the U.S. Food and Drug Administration have been principally implicated in NSF, including gadodiamide, gadopentetate, and gadoversetamide. Gadobenate has also been associated with NSF, but further research has shown that gadobenate diglumine might be safe even in patients undergoing dialysis.
The first cases of NSF were identified in 1997, but NSF was first described as an independent disease entity in 2000. While skin involvement is on the foreground, the process may involve any organ and resembles diffuse scleroderma or systemic sclerosis. In 2006, the link between NSF and gadolinium-containing contrast agents was made. As a result, gadolinium-containing contrast is now considered contraindicated in patients with an estimated glomerular filtration rate (a measure of renal function) under 60 and especially under 30 ml/mn. One retrospective study of the Veterans Affairs Electronic Medical Record found no cases of NSF among 141 patients receiving hemodialysis for chronic kidney disease who received gadoteridol.
During pregnancy, the placenta, which is fetal tissue, synthesizes large amounts of estrogen. The levels of estrogen in the mother can elevate 100-fold higher than normal cycling levels. In fetal aromatase deficiency, the placenta synthesizes the intermediates in the biosynthesis of the estrogens, androstenedione and testosterone, but cannot convert them the rest of the way due to the absence of aromatase. These compounds, which are androgens, subsequently accumulate to high levels and circulate, severely masculinizing both the fetus and the mother. The mother will experience cystic acne, hirsutism, deepening of the voice, and clitoromegaly, which will partially reverse following parturition. The fetus, if female, will be born with severely masculinized external genitalia, including labioscrotal fusion and a greatly enlarged phallus. A male fetus will be born with normal genitalia.
At puberty, due to the lack of aromatase, estrogens will not be synthesized by the ovaries, and normal puberty, including breast development and the onset of menses, will not occur. Instead, androgens will elevate once again above normal levels, and may cause additional virilization, such as acne, hirsutism, and further enlargement of the clitoris, unless treatment with estrogen is given.
Aromatase deficiency in the baby can also affect the mother during gestation, with cystic acne, hirsutism, deepening of the voice, and clitoromegaly. Increased circulating testosterone levels are the cause. The mother's symptoms resolve after she gives birth.
Renal tuberculosis
And other causes of hypercalcemia (and thus hypercalciuria)
- Immobilization (leading to hypercalcemia and hypercalciuria)
- Milk-alkali syndrome
- Hypervitaminosis D
- Multiple myeloma
The prognosis of nephrocalcinosis is determined by the underlying cause. Most cases of nephrocalcinosis do not progress to end stage renal disease, however if not reated it can lead to renal dysfunction this includes primary hyperoxaluria, hypomagnesemic hypercalciuric nephrocalcinosis and Dent's disease. Once nephrocalcinosis is found, it is unlikely to be reversed, however, partial reversal has been reported in patients who have had successful treatment of hypercalciuria and hyperoxaluria following corrective intestinal surgery.
Other causes of acquired NDI include: low blood potassium, post-obstructive polyuria, sickle cell disease/trait, amyloidosis, Sjogren syndrome, renal cystic disease, Bartter syndrome, and various medications (Amphotericin B, Orlistat, Ifosfamide, Ofloxacin, Cidofovir, Vaptanes).
In addition to kidney and systemic disorders, nephrogenic DI can present itself as a side-effect to some medications. The most common and well known of these medications is lithium, although there are many other medications that cause this effect with lesser frequency.
McCune–Albright syndrome is suspected when two or more of the following features are present:
- Hyperfunctioning endocrine disease (gonadotropin independent precocious puberty, hyperthyroidism, growth hormone excess, neonatal Cushing syndrome)
- Fibrous dysplasia
- Café au lait macules
Patients may have one or many of these features, which may occur in any combination.
The clinical presentation varies greatly depending on the disease features. Patients with fibrous dysplasia may have bone fractures, pain, and deformities.
Cafe-au-lait skin macules tend to have characteristic features, including jagged "coast of Maine" borders, and location respecting the midline of the body.
Endocrine disease in McCune–Albright syndrome results from increased hormone production. The most common endocrinopathy is precocious puberty, which presents in girls with recurrent estrogen-producing cysts leading to episodic breast development, growth acceleration, and vaginal bleeding. Precocious puberty may also occur in boys with McCune–Albright syndrome, but is much less common. Additional potential endocrinopathies include hyperthyroidism and growth hormone excess. Cushing syndrome is a very rare feature that develops only in infancy. Patients with polyostotic fibrous dysplasia may develop low blood phosphate levels due to overproduction of the hormone fibroblast growth factor-23.
McCune–Albright syndrome has different levels of severity. For example, one child with McCune–Albright syndrome may be entirely healthy, with no outward evidence of bone or endocrine problems, enter puberty at close to the normal age, and have no unusual skin pigmentation. Diagnosis may be made only after decades. In other cases, children are diagnosed in early infancy, show obvious bone disease, and obvious increased endocrine secretions from several glands.
Even though there is no evidence of malignant potential, transurethral resection is recommended together with long-term antibiotic prophylaxis for at least one year after resection. Prolonged antibiotic therapy is suggested due to the frequent finding of UTI as an associated or causative factor.
Nephrogenic adenoma, also mesonephric adenoma and nephrogenic metaplasia, is a benign growth typically found in the urinary bladder.
It is thought to result from displacement and implantation of renal tubular cells, as this entity in kidney transplant recipients has been shown to be kidney donor derived.
This entity should not be confused with the similar-sounding "metanephric adenoma".
Psychosocial short stature (PSS) or psychosocial dwarfism, sometimes called psychogenic or stress dwarfism, or Kaspar Hauser syndrome, is a growth disorder that is observed between the ages of 2 and 15, caused by extreme emotional deprivation or stress.
The symptoms include decreased growth hormone (GH) and somatomedin secretion, very short stature, weight that is inappropriate for the height, and immature skeletal age. This disease is a progressive one, and as long as the child is left in the stressing environment, his or her cognitive abilities continue to degenerate. Though rare in the population at large, it is common in feral children and in children kept in abusive, confined conditions for extended lengths of time. It can cause the body to completely stop growing but is generally considered to be temporary; regular growth will resume when the source of stress is removed.
Placental villous immaturity, also villous immaturity and villous dysmaturity, is chorionic villous development that is inappropriate for the gestational age.
It is associated with diabetes mellitus
and fetal death near term, i.e. intrauterine demise close to the normal gestational period.
This form of DI can also be hereditary due to defects in either of the following genes:
Placental villous immaturity, as the name implies, is characterized by chorionic villi that are inappropriately developed for the gestational age. The development and maturation of chorionic villi is essential for normal fetal development.
Immature chorionic villi are larger and have more central blood vessels; thus, the diffusion distance for gas and nutrient exchange is larger and, therefore, placental function is impaired.
Psychogenic polydipsia is found in patients with mental illnesses, most commonly schizophrenia, but also anxiety disorders and rarely affective disorders, anorexia nervosa and personality disorders. PPD occurs in between 6% and 20% of psychiatric inpatients. It may also be found in people with developmental disorders, such as those with autism. While psychogenic polydipsia is usually not seen outside the population of those with serious mental disorders, it may occasionally be found among others in the absence of psychosis, although there is no existent research to document this other than anecdotal observations. Such persons typically prefer to possess bottled water that is ice-cold, consume water and other fluids at excessive levels. However, a preference for ice-cold water is also seen in diabetes insipidus.