Breast cancer presenting with the syndrome of inappropriate secretion of antidiuretic hormone after simple mastectomy.
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A 71-year-old woman showed disorientation 7 days after simple mastectomy for right breast cancer. Computed tomography of the brain was normal. The level of serum sodium was very low (110 mEq/l), while the urine sodium level was normal. The osmolality of urine was higher (342 mosmol/kg) than that of serum (220 mosmol/kg). These data suggested a syndrome of inappropriate secretion of antidiuretic hormone. A fluid restriction, infusion of hypertonic saline and administration of diuretics gradually increased the level of serum sodium. Subsequently, disorientation disappeared. This is a rare case of the syndrome of inappropriate secretion of antidiuretic hormone caused by simple mastectomy, a relatively minor surgical procedure. (+info)
Syndrome of inappropriate secretion of ADH (SIADH) following cisplatin administration in a pulmonary adenocarcinoma patient with a malignant pleural effusion.
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We report a patient with pulmonary adenocarcinoma complicated by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) following systemic chemotherapy with cisplatin (CDDP) and vindesine (VDS). A 66-year-old woman was diagnosed as having pulmonary adenocarcinoma with malignant pleural effusion following investigations for cough and dyspnea. After drainage of the effusion she received combination chemotherapy with CDDP and VDS. She developed SIADH 48 hours following chemotherapy. Interestingly, the use of carboplatin (CBDCA) and VDS in the subsequent treatment course was well tolerated indicating that the SIADH was most likely to have been induced by administration of CDDP. (+info)
Overexpression of vasopressin in the rat transgenic for the metallothionein-vasopressin fusion gene.
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Arginine vasopressin (AVP) is a major antidiuretic hormone, the overproduction of which causes diluting hyponatremia in humans and is called the syndrome of inappropriate antidiuresis (SIAD). To study physiological changes resulting from AVP overproduction and to develop an animal model of hyponatremia, the human AVP gene was expressed under the control of the metallothionein promoter in transgenic (Tg) rats. Analyses of AVP immunoreactivity (irAVP) in the tissues revealed that the transgene is expressed mainly in the central nervous system. Gel filtration showed that irAVP in the brain and plasma was properly processed AVP. AVP purified from the brains of both Tg and control rats also exerted equal bioactivity to generate cAMP in LLC-PK1 cells. The founder rats did not show any physical or anatomical abnormalities. Under basal conditions, Tg rats had high plasma AVP levels (Tg 13.8 +/- 2.5 pg/ml; control 2.7 +/- 1.2 pg/ml; n=6 in both groups; means +/- S.E.M.), decreased urine volume, and normal plasma [Na(+)]. Hypertonic saline injected i.p. did not affect AVP secretion in Tg rats. In response to a zinc-supplemented liquid diet, plasma AVP decreased in control rats, but increased in Tg rats (Tg 32.7 +/- 2.7 pg/ml; control 1.0+/-0.1 pg/ml; n=6), resulting in hyponatremia (Tg 135.2 +/- 2.5 mEq/l; control 140.8 +/- 0.4 mEq/l; n=6). To our knowledge, this is the first transgenic animal to show diluting hyponatremia. This transgenic rat may therefore provide a useful model in which to investigate various physiological alterations resulting from the oversecretion of AVP which involve SIAD, stress response, behavior, and blood pressure. (+info)
Efficacy of phenytoin against hyponatremic seizures due to SIADH after administration of anticancer drugs in a neonate.
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A neonate with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) developed refractory hyponatremic seizures following administration of anticancer drugs. The seizures did not respond to diazepam, phenobarbital, or lidocaine, but resolved immediately with administration of phenytoin. The low water-excretion capacity in neonates should be taken into consideration when fluid loading is attempted, to avoid renal damage upon administration of drugs such as cisplatin that have a potential damaging effect on the kidney. Phenytoin could be the therapy of choice for SIADH and resulting seizures in the neonatal period. (+info)
The hyponatremic patient: a systematic approach to laboratory diagnosis.
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Hyponatremia (serum sodium level less than 134 mmol/L) is a common electrolyte disturbance. Its high prevalence and potential neurologic sequelae make a logical and rigorous differential diagnosis mandatory before any therapeutic intervention. A history of concurrent illness and medication use as well as the assessment of extracellular volume status on physical examination may provide useful clues as to the pathogenesis of hyponatremia. Measurement of the effective serum tonicity (serum osmolality less serum urea level) is the first step in the laboratory evaluation. In patients with normal or elevated effective serum osmolality (280 mOsm/kg or greater), pseudohyponatremia should be excluded. In the hypo-osmolar state (serum osmolality less than 280 mOsm/kg), urine osmolality is used to determine whether water excretion is normal or impaired. A urine osmolality value of less than 100 mOsm/kg indicates complete and appropriate suppression of antidiuretic hormone secretion. A urine sodium level less than 20 mmol/L is indicative of hypovolemia, whereas a level greater than 40 mmol/L is suggestive of the syndrome of inappropriate antidiuretic hormone secretion. Levels of hormones (thyroid-stimulating hormone and cortisol) and arterial blood gases should be determined in difficult cases of hyponatremia. (+info)
An autopsy case of amyotrophic lateral sclerosis accompanied by syndrome of inappropriate secretion of antidiuretic hormone.
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We report an autopsy-confirmed case of amyotrophic lateral sclerosis (ALS) accompanied by syndrome of inappropriate secretion of antidiuretic hormone (SIADH). A 67-year-old man was admitted to our hospital with muscle weakness, dysarthria and dysphagia. During hospitalization, respiratory insufficiency was ingravescent, and hyponatremia, hypo-osmolarity, elevated osmotic pressure of urine, and elevated urinary sodium excretion were noted. Based on these findings we diagnosed ALS with SIADH, and treatment with infusion of concentrated NaCl was started. However, the patient died of respiratory failure on day 50. We assumed that severely restrictive ventilatory impairment was the cause of SIADH in this case. (+info)
Vasopressin V2 receptor antagonists.
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Hyponatremia, whether due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or disorders of water retention such as congestive heart failure and cirrhosis, is a very common problem encountered in the care of medical patients. To date, available treatment modalities for disorders of excess arginine vasopressin (AVP) secretion or action have been limited and suboptimal. The recent discovery and development of nonpeptide AVP V(2) receptor antagonists represents a promising new treatment option to directly antagonize the effects of elevated plasma AVP concentrations at the level of the renal collecting ducts. By decreasing the water permeability of renal collecting tubules, excretion of retained water is promoted, thereby normalizing or improving hypo-osmolar hyponatremia. In this review, SIADH and other water retaining disorders are briefly discussed, after which the published preclinical and clinical studies of several nonpeptide AVP V(2) receptor antagonists are summarized. The likely therapeutic indications and potential complications of these compounds are also described. (+info)
Severe hyponatraemia: investigation and management in a district general hospital.
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AIMS: To study the incidence, investigation, and management of severe hyponatraemia (serum sodium < 120 mmol/litre) over a period of six months in a district general hospital. METHODS: The laboratory computer was used to identify all inpatients who had a serum sodium concentration of less than 120 mmol/litre over a six month period. The records of these patients were reviewed for the relevant demographic, clinical, and laboratory data, in addition to diagnosis, treatment, and outcome of hospitalisation. RESULTS: Forty two patients were studied, with a female to male ratio of 2 : 1. Nine patients had central nervous system symptoms, and four of these patients died in hospital. Only 14 patients had their urinary electrolytes and/or osmolality checked. A diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was mentioned in eight patients, sometimes without checking their urinary electrolytes or osmolality. Twenty one patients died in hospital. The patients who died did not have lower serum sodium values or a higher rate of correction of hyponatraemia, but they all suffered from advanced medical conditions. CONCLUSIONS: The possible cause of hyponatraemia should always be sought and that will require an accurate drug history, clinical examination, and assessment of fluid volume, plus the measurement of urinary electrolytes and osmolality in a spot urine sample. The diagnosis of SIADH should not be confirmed without the essential criteria being satisfied. The current or recent use of diuretics is a possible pitfall in the diagnosis of SIADH. The rate of serum sodium correction of less than 10 mmol/day is probably the safest option in most cases. (+info)