pituitrin and Demyelinating-Diseases

Hyponatremia and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are associated with significant mortality and morbidity. The effectiveness and safety of oral urea for SIADH are still debated.. To evaluate the efficacy and safety of urea for the treatment of SIADH.. A systematic search of Medline and Embase was conducted for controlled and uncontrolled studies of urea for SIADH in adult patients. The primary outcome was serum sodium concentration after treatment. Secondary outcomes included the proportion of patients with osmotic demyelination syndrome (ODS), intracranial pressure, and resource use such as length of stay.. Twenty-three studies involving 537 patients with SIADH were included, of which 462 were treated with urea. The pooled mean baseline serum sodium was 125.0 mmol/L (95% CI, 122.6-127.5 mmol/L). The median treatment duration with oral urea was 5 days. Urea increased serum sodium concentration by a mean of 9.6 mmol/L (95% CI, 7.5-11.7 mmol/L). The mean increase in serum sodium after 24 hours was 4.9 mmol/L (95% CI, 0.5-9.3 mmol/L). Adverse events were few, mainly consisting of distaste or dysgeusia, and no case of ODS was reported. Resource use was too infrequently reported to be synthesized.. In this systematic review of the use of urea in SIADH and despite the lack of randomized clinical trials, lower-quality evidence was identified that suggests that urea may be an effective, safe, and inexpensive treatment modality that warrants further exploration.

Topics: Adult; Demyelinating Diseases; Humans; Inappropriate ADH Syndrome; Sodium; Urea; Vasopressins

Abnormalities in thirst and vasopressin (AVP) release play key roles in the genesis of hyponatremia; both processes are under the control of osmoreceptive neurons in the central nervous system (CNS). The acute development of hyponatremia in turn leads to profound cerebral edema, whereas treatment of chronic hyponatremia can be associated with osmotic demyelination syndrome (ODS). The brain is thus both "culprit" and "victim" in hyponatremia. This review summarizes recent advances in the understanding of osmoreception in the brain, the CNS response to acute and chronic hyponatremia, and the pathophysiology of ODS.

Topics: Animals; Brain; Demyelinating Diseases; Humans; Hyponatremia; Models, Biological; Osmosis; Thirst; Vasopressins

Etiopathogenesis, diagnostics and therapy of hyponatremias are summarized for clinicians. Hyponatremia is the most common electrolyte abnormality. Mild to moderate hyponatremia and severe hyponatremia are found in 15-30% and 1-4% of hospitalized patients, respectively. Pathophysiologically, hyponatremias are classified into two groups: hyponatremia due to non-osmotic hypersecretion of vasopressin (hypovolemic, hypervolemic, euvolemic) and hyponatremia of non-hypervasopressinemic origin (pseudohyponatremia, water intoxication, cerebral salt wasting syndrome). Patients with mild hyponatremia are almost always asymptomatic. Severe hyponatremia is usually associated with central nervous system symptoms and can be life-threatening. Diagnostic evaluation of patients with hyponatremia is directed toward identifying the extracellular fluid volume status, the neurological symptoms and signs, the severity and duration of hyponatremia, the rate at which hyponatremia developed. The first step to determine the probable cause of hyponatremia is the differentiation of the hypervasopressinemic and non-hypervasopressinemic hyponatremias with measurement of plasma osmolality, glucose, lipids and proteins. For further differential diagnosis of hyponatremia, the determination of urine osmolality, the clinical assessment of extracellular fluid volume status and the measurement of urine sodium concentration provide important information. The most important representative of euvolemic hyponatremias is SIADH. The diagnosis of SIADH is based on the exclusion of other hyponatremic conditions; low plasma osmolality (<275 mosmol/kg) and inappropriate urine concentration (urine osmolality >100 mosmol/kg) are of pathognomic value. Acute (<48 hrs) severe hyponatremia (<120 mmol/l) necessitates emergency care with rapid restoration of normal osmotic milieu (1 mmol/l/hr increase rate of serum sodium). Patients with chronic symptomatic hyponatremia have a high risk of osmotic demyelination syndrome in brain if rapid correction of the plasma sodium occurs (maximal rate of correction of serum sodium should be 0.5 mmol/l/hr or less). The conventional treatments for chronic asymptomatic hyponatremia (except hypovolemic patients) include water restriction and/or the use of demeclocycline or lithium or furosemide and salt supplementation. Vasopressin receptor antagonists have opened a new forthcoming therapeutic era. V2 receptor antagonists, such as lixivaptan, tolvaptan, satavaptan and the V2+

Topics: Antidiuretic Hormone Receptor Antagonists; Azepines; Benzamides; Benzazepines; Blood Volume; Brain Diseases; Central Nervous System; Chronic Disease; Demeclocycline; Demyelinating Diseases; Diagnosis, Differential; Diuretics; Extracellular Fluid; Furosemide; Humans; Hyponatremia; Inappropriate ADH Syndrome; Lithium Compounds; Morpholines; Osmolar Concentration; Osmosis; Pyrroles; Severity of Illness Index; Sodium; Spiro Compounds; Time Factors; Tolvaptan; Vasopressins

Osmotic demyelination of the brain (ODS) is a dreaded complication that typically occurs several days after aggressive therapy for chronic hyponatraemia, but is eminently avoidable. In this teaching exercise, Professor McCance, an imaginary consultant, is asked to explain how he would have treated a 28-year-old female who had hyperkalaemia, hypoglycaemia, hypotension and hyponatraemia (118 mM) to prevent the development of ODS. He begins with a review of the physiology, including his own landmark work on chronic hyponatraemia associated with a contracted extracellular fluid volume. Adding quantitative analysis, the cause of the excessive rise in plasma sodium concentration is revealed, and a better plan for therapy is proposed.

Topics: Addison Disease; Adult; Brain Diseases; Demyelinating Diseases; Female; Humans; Hyperkalemia; Hypoglycemia; Hyponatremia; Hypotension; Renal Agents; Syndrome; Vasopressins; Water-Electrolyte Imbalance

Chlorpropamide (CPM) has been reported to produce impaired water excretion due to the enhancement of renal vasopressin (ADH) action and/or due to centrally enhanced ADH release, but it is still unknown whether CPM gives rise to ADH release with a subsequent hyponatremia in diabetes mellitus (DM), which, in turn, causes an impairment of the central nervous system. In 3 patients with DM, who developed hyponatremia during the treatment with CPM, an acute water load (WL) was carried out in the presence and absence of the drug, and plasma ADH was determined with plasma and urine osmolalities. Moreover, in 2 cases, MRI scans of the brain were taken. In all the patients, acute WL tests failed to suppress completely ADH release in response to changes in plasma osmolality in the presence of CPM, which, in turn, resulted in the impaired water excretion. In the absence of CPM, an acute WL normally suppressed plasma ADH leading to the diuresis. MRI scans illustrated the presence of central pontine myelinolysis. It is likely that CPM might stimulate ADH release in DM with a subsequent hyponatremia and brain damages.

Topics: Aged; Chlorpropamide; Demyelinating Diseases; Diabetes Complications; Diabetes Mellitus; Female; Humans; Hypoglycemic Agents; Hyponatremia; Magnetic Resonance Imaging; Male; Middle Aged; Osmolar Concentration; Pons; Vasopressins

We describe a 71 year old man with a neurodegenerative condition who developed chronic inappropriate antidiuretic hormone secretion and hypothermia resulting in recurrent episodes of impaired consciousness. This combination of abnormalities is attributable to hypothalamic disease and has not to our knowledge been previously reported with clearly documented antidiuretic hormone excess.

Topics: Aged; Chronic Disease; Demyelinating Diseases; Humans; Hyponatremia; Hypothermia; Male; Vasopressins; Water Intoxication

Pontine myelinolysis can be suspected clinically on the basis of the following criteria: (1) Electrolyte disturbance manifested mainly by hyponatremia; (2) progressive neurologic deficits resulting in a "locked-in" syndrome; (3) usually, but not necessarily, alcohol abuse; and (4) frequent iatrogenic precipitation of the syndrome by inappropriate rehydration of patients at risk. A major pathophysiologic mechanism for this disorder seems to be the anatomic grid structure of the base of the pons, which is more vulnerable to edema than the cerebral hemispheres. Treatment should be focused on rapid reversal of electrolyte imbalance and judicious use of dehydrating agents. Early diagnosis and treatment might reverse an otherwise malignant syndrome.

Topics: Adolescent; Adult; Aged; Alcoholism; Brain Edema; Brain Stem; Child; Child, Preschool; Demyelinating Diseases; Female; Humans; Hyponatremia; Male; Middle Aged; Pons; Vasopressins; Water-Electrolyte Imbalance

Autopsy in a patient with severe hyponatremia showed central pontine myelinolysis. Review of our patients with central pontine myelinolysis and those described in the English literature to data disclosed that 61 percent had documented hyponatremia. While the exact mechanism involving hyponatremia and central pontine myelinolysis cannot be defined, a circumstantial relationship is apparent. The purpose of this paper is to emphasize this relationship and to suggest that the possibility of central pontine myelinolysis be considered in any patient with hyponatremia and neurologic dysfunction.

Topics: Alcoholism; Demyelinating Diseases; Diuretics; Fatty Liver; Female; Humans; Hypertension; Hyponatremia; Liver Function Tests; Middle Aged; Pons; Sodium; Vasopressins

Topics: Autopsy; Blood Glucose; Blood Urea Nitrogen; Brain Diseases; Caudate Nucleus; Cerebral Cortex; Corpus Callosum; Creatinine; Demyelinating Diseases; Diabetic Coma; Female; Humans; Hypotension; Male; Metabolic Diseases; Middle Aged; Osmolar Concentration; Pons; Sodium; Vasopressins; Water-Electrolyte Balance

Topics: Autopsy; Chlorthalidone; Demyelinating Diseases; Female; Humans; Hypertonic Solutions; Hyponatremia; Methyclothiazide; Middle Aged; Pons; Potassium; Pulmonary Embolism; Reserpine; Vasopressins; Water-Electrolyte Balance

Topics: Adenosine Triphosphatases; Brain Edema; Demyelinating Diseases; Glucosephosphate Dehydrogenase; Histocytochemistry; Myelin Sheath; Neurochemistry; Neuroglia; Oxidoreductases; Pathology; Rats; Research; Tin; Vasopressins