Pathophysiologic and pharmacologic alterations in the release and action of ADH

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Effect of Geumgwe-Sinkihwan on Renal Dysfunction in Ischemia/Reperfusion-Induced Acute Renal Failure Mice

Renal ischemia-reperfusion (I/R) injury is an important cause of acute renal failure (ARF). Geumgwe-sinkihwan (GSH) was recorded in a traditional Chines medical book named “Bangyakhappyeon” in 1884. GSH has been used for treatment for patients with diabetes and glomerulonephritis caused by deficiency of kidney yang and insufficiency of kidney gi. Here we investigate the effects of GSH in mice model of ischemic acute kidney injury. The mice groups are as follows; sham group: C57BL6 male mice, I/R group: C57BL6 male mice with I/R surgery, GSH low group: I/R + 100 mg/kg/day GSH, and GSH high group: I/R + 300 mg/kg/day GSH. Ischemia was induced by clamping both renal arteries and reperfusion. Mice were orally given GSH (100 and 300 mg/kg/day) during 3 days after surgery. Treatment with GSH significantly ameliorated creatinine clearance, creatinine, and blood urea nitrogen levels. Treatment with GSH reduced neutrophil gelatinase associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1), specific renal injury markers. GSH also reduced the periodic acid–Schiff and picro sirius red staining intensity in kidney of I/R group. Western blot and real-time RT-qPCR analysis demonstrated that GSH decreased protein and mRNA expression levels of the inflammatory cytokines in I/R-induced ARF mice. Moreover, GSH inhibited protein and mRNA expression of inflammasome-related protein including NLRP3 (NOD-like receptor pyrin domain-containing protein 3, cryoprin), ASC (Apoptosis-associated speck-like protein containing a CARD), and caspase-1. These findings provided evidence that GSH ameliorates renal injury including metabolic dysfunction and inflammation via the inhibition of NLRP3-dependent inflammasome in I/R-induced ARF mice.

Paraneoplastic Syndromes Associated with Laryngeal Cancer

OBJECTIVES

Paraneoplastic syndromes occur rarely in association with laryngeal cancer. When present, the syndrome may be the first sign of the malignancy. The aim of the present study was to review and report on all published cases in the international literature.

METHODS

A search of PubMed was conducted for "paraneoplastic syndromes in laryngeal cancer" without any restrictions on language or publication year. The full texts of all relevant articles were reviewed and all cases of paraneoplastic syndromes associated with any type of laryngeal cancer were extracted and analyzed.

RESULTS

We identified 59 cases of paraneoplastic syndromes related to laryngeal cancer in the literature published from 1963 until recently. There were 46 squamous cell carcinomas and 10 neuroendocrine carcinomas. Twenty-two of the paraneoplastic syndromes involved the endocrine system, 21 were dermatologic or cutaneous, 8 neurologic, 5 osteoarticular or rheumatologic, 1 ocular, 1 muscular, and 1 hematologic. Treatment strategies included surgery, radiotherapy, chemotherapy, and often multimodal therapy, depending on the histology and stage of the laryngeal cancer.

CONCLUSIONS

Because of their rarity, paraneoplastic syndromes associated with laryngeal cancer are difficult to diagnose. By presenting and systematically reviewing all published cases in the international literature, the present review may help clinicians to recognize them and to suspect the diagnosis of laryngeal cancer at an earlier stage than otherwise might be possible.

SIADH Induced by Pharyngeal Squamous Cell Carcinoma: Case Report and Literature Review

Background. The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is considered to be the most common cause of euvolemic hyponatremia. The most common malignancy associated with SIADH is small cell lung cancer. We present a rare case of a patient with SIADH secondary to well differentiated squamous cell carcinoma of the naso-oropharynx. Case. A 46-year-old Caucasian woman presented to emergency department with four-week history of progressive dysphagia. On examination, she was found to have a pharyngeal mass. CT scan and MRI of neck confirmed a mass highly suspicious of carcinoma. Patient's serum sodium level decreased to 118 mEq/L and other labs including serum and urine osmolality confirmed SIADH. She was started on fluid restriction and oral sodium tablets which gradually improved her serum sodium levels. Biopsy confirmed diagnosis of squamous cell carcinoma of pharynx. Conclusion. SIADH can be caused by squamous cell carcinoma. Appropriate management includes fluid restriction.

A Case Report and Review of the Literature

A case report of a patient who developed water intoxication during carbamazepine therapy is described. The discontinuation of carbamazepine, along with supportive care, resulted in spontaneous diuresis and the resolution of both the laboratory and clinical signs and symptoms of water intoxication.

A review of the literature regarding carbamazepine-associated water intoxication and a discussion of the mechanism of its antidiuretic effect is presented.

Paraneoplastic Syndromes in Patients with Cancer of the Larynx and Hypopharynx

Paraneoplastic syndromes may be the first sign of a malignancy. They are systemic, nonmetastatic manifestations associated with a variety of malignant neoplasms and occurring in a minority of cancer patients. These associations of symptoms and signs are not directly related to the site or local manifestations of a malignant tumor or its metastases, but their recognition may facilitate the detection of malignancies or recurrences. Paraneoplastic syndromes are categorized into 6 types: Dermatologic or cutaneous, endocrine, hematologic, neurologic, osteoarticular or rheumatologic, and ocular. Different oncotypes have rarely been associated with paraneoplastic syndromes in patients with cancer of the larynx and hypopharynx. The world literature has been reviewed.

Hyponatremia as the Initial Presentation of Cryptococcal Meningitis After Liver Transplantation

INTRODUCTION

Meningoencephalitis is the most common clinical manifestation of cryptococcal infection, as the organism has a propensity to invade the CNS. Patients often present with elevated intracranial pressure, focal motor deficits, altered mentation and internal hydrocephalus. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been reported as a notable cause of euvolemic hyponatremia in immunocompromised patients.

CASE PRESENTATION

A 67-year-old male with liver transplantation due to hepatitis C (HCV) related liver cirrhosis developed severe hyponatremia four months after liver transplantation, which was discovered during routine clinic visit. Patient was referred to the emergency department, treated and discharged with normal serum sodium level. Few days later, he presented with dizziness, confusion, ataxia, abnormal muscle movements and leg pain. Laboratory investigations were consistent with SIADH and revealed a sodium level of 115 mmol/L. Brain MRI showed a leptomeningeal enhancement in the superior cerebellar sulci suspicious for infection. Lumbar puncture was performed and consistent with Cryptococcus neoformans infection; therefore, cryptococcal meningitis was diagnosed. Amphotericin B was started for the patient for six weeks followed by fluconazole for one year. His level of consciousness improved significantly, and his serum sodium level slowly returned to its normal baseline over three weeks after starting amphotericin B.

CONCLUSIONS

Symptomatic hyponatremia secondary to SIADH remains a rare complication of cryptococcal meningitis.

Syndrome of inappropriate anti-diuretic hormone in non-small cell lung carcinoma: a case report

Paraneoplastic syndrome (PNS) related to lung cancer is very common. However, the syndrome of inappropriate anti-diuretic hormone secretion (SIADH) is rare in non-small cell lung cancer (NSCLC). We are reporting the case of a 58-year-old female presenting with dyspnea, cough, weight loss, digital clubbing, and one week of haemoptysis. CT showed a mediastinal mass completely encasing her superior vena cava, causing significant narrowing of the trachea and right mainstem bronchus. Bronchoscopy and biopsy identified a non-resectable NSCLC. Palliative radiation therapy was initiated. The day after her first radiation treatment, the patient developed asymptomatic hyponatremia, confirmed to be SIADH by laboratory evaluation. NSCLC-associated SIADH has been reported only thrice over the past two decades and never following radiation therapy with clinical improvement. The patient was discharged home on fluid restriction after her respiratory status improved to continue outpatient radiation and chemotherapy. SIADH in the setting of NSCLC is discussed.

Hyponatraemia masking the diagnosis of cryptococcal meningitis

Patients with acute hyponatraemia present with neurologic symptoms resulting from cerebral oedema induced by water movement into the brain. The author reports a male patient who presented to our emergency department with headache for 3 days and confusion for a day. The reported patient was on two immunosuppressive drugs, namely prednisone and azathiorprine for his ulcerative colitis. Laboratory data were consistent with syndrome of inappropriate antidiuretic hormone secretion (SIADH) which was appropriately corrected; however his mental status deteriorated. The patient's initial presentation was considered to be secondary to hyponatraemia. There was lapse of 36 h where the hyponatraemia was corrected; however the cause of the SIADH was not investigated. On further investigation of the patient a diagnosis of cryptococcal meningitis was ascertained. This case highlights the importance of considering a central nervous system infection in an immuno-suppressed patients presenting with hyponatraemia secondary to SIADH.

Oxytocin receptors in the primate ovary: molecular identity and link to apoptosis in human granulosa cells

BACKGROUND

Oxytocin (OT) is produced by granulosa cells (GCs) of pre-ovulatory ovarian follicles and the corpus luteum (CL) in some mammalian species. Actions of OT in the ovary have been linked to luteinization, steroidogenesis and luteolysis. Human IVF-derived (h)GCs possess a functional OT receptor (OTR), linked to elevation of intracellular Ca(2+), but molecular identity of the receptor for OT in human granulosa cells (hGCs) and down-stream consequences are not known.

METHODS AND RESULTS

RT-PCR, sequencing and immunocytochemistry identified the genuine OTR in hGCs. OT (10 nM-10 microM) induced elevations of intracellular Ca(2+) levels (Fluo-4 measurements), which were blocked by tocinoic acid (TA; 50 microM, a selective OTR-antagonist). Down-stream effects of OTR-activation include a concentration dependent decrease in cell viability/metabolism, manifested by reduced ATP-levels, increased caspase3/7-activity (P < 0.05) and electron microscopical signs of cellular regression. TA blocked all of these changes. Immunoreactive OTR was found in the CL and GCs of large and, surprisingly, also small pre-antral follicles of the human ovary. Immunoreactive OTR in the rhesus monkey ovary was detected in primordial and growing primary follicles in the infantile ovary and in follicles at all stages of development in the adult ovary, as well as the CL: these results were corroborated by RT-PCR analysis of GCs excised by laser capture microdissection.

CONCLUSIONS

Our study identifies genuine OTRs in human and rhesus monkey GCs. Activation by high levels of OT leads to cellular regression in hGCs. As GCs of small follicles also express OTRs, OT may have as yet unknown functions in follicular development.

Sarcoidosis presenting with diabetes insipidus followed by acute cranial nerve syndrome. A case report

Diabetes insipidus in a previously healthy 16-year-old girl led to surgical exploration of a pituitary stalk intumescence detected by oxygen cisternography with the use of tomography. Biopsy of the pituitary stalk contained chronically inflamed brain tissue. Subsequent liver and bone biopsies showed characteristic granulomata, confirming the diagnosis of sarcoidosis. Subfrontal craniotomy was followed by a rapidly progressive basal meningoencephalitis with multiple cranial nerve involvement. The need to establish a causal diagnosis in diabetes insipidus is stressed. The rarity of the disorder and the presumed role of subfrontal craniotomy with regard to the flare-up of the sarcoidosis of the brain are discussed.

The syndrome of inappropriate secretion of antidiuretic hormone. A case report

A 72-year-old woman with the syndrome of inappropriate secretion of antidiuretic hormone of unknown cause during more than one year of observation is reported. Plasma vasopressin levels were excessively elevated, even during a water load test. Her serum electrolyte abnormalities and general state were ameliorated after fluid restriction. During treatment with demeclocycline the patient was able to increase fluid without deterioration.

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion caused by squamous cell carcinoma of the nasopharynx: case report

The Paraneoplastic syndromes include the disorders that accompany benign or malignant tumors but are not directly related to mass effects or invasion by the primary tumor or its metastases. Neoplastic cells can produce a variety of peptides that exert biologic actions at local and distant sites and can elicit responses that cause a variety of hormonal, hematologic, dermatologic and neurologic symptoms. Almost every type of malignancy has the potential to produce hormones or cytokines or to induce immunologic responses. Lung cancers, both non-small cell and small cell, are capable of producing a variety of paraneoplastic syndromes. The majority of such syndromes are caused by small cell carcinomas, including many endocrinopathies. Syndrome of inappropriate antidiuretic hormone (SIADH) has been commonly associated with small cell carcinoma and is often seen in these patients. However, SIADH associated with squamous cell carcinoma has rarely been reported on, and the mechanism for this rare association is still unknown. We present here a case of a 77-yr-old man who developed SIADH caused by squamous cell carcinoma of the nasopharynx.

Paraneoplastic syndromes in patients with primary head and neck cancer

Paraneoplastic syndromes represent the clinical manifestations of the indirect and remote effects produced by tumor metabolites or other products. The clinical spectrum of the various paraneoplastic syndromes related to primary malignancies of the head and neck region is presented. A review of the literature on paraneoplastic syndromes in patients with primary head and neck cancer was carried out. Paraneoplastic syndromes related to primary malignancies of the head and neck region can be categorized as: endocrine, cutaneous or dermatologic, hematologic, neurologic, osteoarticular or rheumatologic, ocular syndromes. Sometimes, paraneoplastic syndromes can be more serious than the consequences of the primary tumor itself and can precede, follow or be concurrent to the diagnosis of a malignancy; moreover, they can dominate the clinical picture and thus lead to errors with respect to the origin and type of the primary tumor. Physicians who deal with cancer-associated syndromes should be able to differentiate the paraneoplastic syndromes from the benign disorders that mimic them. Patients with a suspected paraneoplastic disorder should undergo a complete panel of laboratory studies, in addition to imaging studies and endoscopy. Identification of paraneoplastic syndromes allow the clinician to make an early diagnosis and to provide adequate treatment of tumors, with a favorable oncologic outcome and improved life expectancy for the patient. These syndromes can follow the clinical course of the tumor and thus be useful for monitoring its evolution.

Syndrome of inappropriate antidiuretic hormone secretion in a patient with cryptococcal meningoencephalitis: a hidden mediastinal small cell carcinoma

We report a 59-year-old man with cryptococcal meningoencephalitis who presented with typical features of syndrome of inappropriate antidiuretic hormone secretion (SIADH). There was no evidence of lung disease or drugs causing SIADH. Studies for endocrine functions and tumor markers were normal. The patient's hyponatremia was refractory to treatment (Na 120-125 mmol/L) after resolution of the cryptococcal infection. Three months after completion of antifungal treatment, a radiograph of the chest disclosed widening of the mediastinum. Computed tomography revealed a mediastinal mass. A tentative diagnosis of extrapulmonary cryptococcoma or a tumor was made. Positron emission tomography using F-fluorodeoxy glucose demonstrated an intense uptake mass in the mediastinum without lesions elsewhere in the body. A biopsy of the mass clearly showed small cell carcinoma (SCC) with positive immunoreactivity for arginine vasopressin and atrial natriuretic peptide. The hyponatremia completely resolved and tumor size dramatically decreased after chemotherapy. To the best of our knowledge, this is the first case of mediastinal SCC associated with SIADH. Patients with otherwise unexplained SIADH should be meticulously scrutinized for a possible malignancy.

Yukmijihwang-tang ameliorates ischemia/reperfusion-induced renal injury in rats

The present study was designed to examine whether Yukmijihwang-tang (YJT), which is a Korean decoction for the treatment of renal disease, has an effect on renal functional parameters in association with the expression of aquaporin 2 (AQP 2), Na,K-ATPase, heme oxygenase-1 (HO-1) in rats with ischemia/reperfusion-induced acute renal failure (ARF). Polyuria caused by down-regulation of renal AQP 2 in the ischemia/reperfusion-induced ARF rats was markedly restored by administration of YJT (100 or 200 mg/kg, p.o.) with restoring expression of AQP 2 in the kidney. The expressions of Na,K-ATPase alpha1 and beta1 subunits in the renal medulla and cortex of the ARF rats were also restored in them by the administration of YJT. Administration of YJT lowered the expression of renal HO-1, which was up-regulated in rats with ischemia/reperfusion-induced ARF. The renal functional parameters including creatinine clearance, urinary sodium excretion, urinary osmolality, and solute-free reabsorption were also markedly restored in ischemia-ARF rats by administration of YJT. Histological study also showed that renal damages in the ARF rats were abrogated by administration of YJT. Taken together, these data indicate that YJT ameliorates renal defects in rats with ischemia/reperfusion-induced ARF.

Hyponatremia and Arginine Vasopressin Dysregulation: Mechanisms, Clinical Consequences, and Management

Hyponatremia, the most common electrolyte disorder, occurs frequently in older people and in hospitalized patients. Physiological changes of aging that interact with diseases and drugs commonly present in older people put this population at greater risk for hyponatremia. It can accompany central nervous system disorders, pulmonary and renal disease, cancer, congestive heart failure, and liver cirrhosis, as well as many commonly used drugs. Delayed recognition can lead to symptomatic hyponatremia with consequent cerebral edema and possibly irreversible neurological damage. Symptoms and signs of hyponatremia may be subtle or not attributed to hyponatremia. Most cases are of the euvolemic type, in which extracellular fluid volume is normal and is often due to the syndrome of inappropriate secretion of antidiuretic hormone. Hyponatremia can also occur in association with hypervolemia or hypovolemia. Common to all of these circumstances is increased secretion of arginine vasopressin (AVP). Understanding of the pathophysiological basis of hyponatremia and of brain compensatory mechanisms is critical to safe treatment. Fluid restriction or infusion of hypertonic saline can improve symptoms and normalize serum sodium levels but does not address excess AVP, which in most cases is the underlying cause of the disorder. A major new approach to treatment of hyponatremia is the development of aquaretics: AVP-receptor antagonists that provide a targeted therapeutic approach to correcting the many kinds of hyponatremia caused by excess AVP levels.

Is hyperosmotic neurosecretion from motor nerve endings a calcium-dependent process?

Spontaneous liberation of neurotransmitter quanta is strongly affected by the osmotic pressure of the extracellular fluid. Elevation of the osmolarity by 20-30% increases the rate of release from motor nerve endings by more than one order of magnitude. In this respect the neuromuscular junction resembles some other secretory systems. The mechanism of this hyperosmotic neurosecretion is not yet understood; extracellular calcium ions are not directly responsible, since this effect can be produced in their absence. Recently, it has been suggested that the liberation of neurotransmitter is regulated by the intracellular concentration of free calcium ions. We have therefore examined the hypothesis that hyperosmotic neurosecretion originates from an increase in internal calcium concentration ([Ca]in). At the frog neuromuscular synapse however, it is impossible at present to estimate directly free [Ca]in; hence we used an indirect technique, which is based on two assumptions; first, the frequency of the miniature endplate potentials (m.e.p.p.s.) reflects free [Ca]in. Second, the movement of calcium ions across the presynaptic membrane is governed by the electrochemical gradient, and by the calcium conductance (g(Ca)). If hyperosmotic neurosecretion is caused by an increase in [Ca]in, then increasing g(Ca), under reversed electrochemical gradient for the calcium should cause a reduction in the effect of hyperosmotic stress on transmitter release. We report that hyperosmotic neurosecretion is dependent on [Ca]in.

Rehmannia glutinose Ameliorates Renal Function in the Ischemia/Reperfusion-Induced Acute Renal Failure Rats

The present study was designed to examine whether aqueous extract of steamed root of Rehmannia glutinose (ARR) has an ameliorative effect on renal functional parameters in association with the expressions of aquaporin 2 (AQP 2), Na,K-ATPase, and heme oxygenase-1 (HO-1) in the ischemia-reperfusion induced acute renal failure (ARF) rats. Polyuria caused by down-regulation of renal AQP 2 in the ischemia-induced ARF rats was markedly restored by administration of ARR (200 mg/kg, p.o.) with restoring expression of AQP 2 in the kidney. The expressions of Na,K-ATPase alpha1 and beta1 subunits in the renal medullar and cortex of the ARF rats were also restored in the ARF rats by administration of ARR. On the other hand, administration of ARR lowered the renal expression of HO-1 up-regulated in rats with ischemia-induced ARF. The renal functional parameters including creatinine clearance, urinary sodium excretion, urinary osmolality, and solute-free reabsorption were also markedly restored in ischemia-ARF rats by administration of ARR. Taken together, these data indicate that RSR ameliorates renal defects in rats with ischemia-induced ARF.

Lithospermic acid B isolated from Salvia miltiorrhiza ameliorates ischemia/reperfusion-induced renal injury in rats

The present study was designed to examine whether lithospermic acid B (LSB) isolated from Salvia miltiorrhiza has an ameliorative effect on renal functional parameters in association with the expression of aquaporin 2 (AQP 2) and Na,K-ATPase in the ischemia-reperfusion induced acute renal failure (ARF) rats. LSB showed strong antioxidant activity against production of reactive oxygen species (ROS), ROS-induced hemolysis, and production of lipid peroxide in a dose-dependent manner. Polyuria caused by down-regulation of renal AQP 2 in the ischemia-reperfusion induced ARF rats was partially restored by administration of LSB (40 mg/kg, i.p.), restoring expression of AQP 2, in renal inner and outer medulla. The expression of Na,K-ATPase alpha1 subunit in outer medulla of the ARF rats was also restored in the ARF rats by administration of LSB, while beta1 subunit level was not altered. The renal functional parameters including creatinine clearance, urinary sodium excretion, urinary osmolality, and solute-free reabsorption were also partially restored in ischemia-ARF rats by administration of LSB. Histological study also showed that renal damages in the ARF rats were abrogated by administration of LSB. Taken together, these data indicate that LSB ameliorates renal defects in rats with ischemia-reperfusion induced ARF, most likely via scavenging of ROS.

Complications of head injury

Management of head injury is based on two concepts, proper treatment of the acute insult and the prevention and treatment of secondary insults. The head injured patient is subject to both intracranial and extracranial secondary insults. This paper will review complications related to the central nervous system as well as the pulmonary, infectious, gastrointestinal, and psychiatric complications frequently seen following traumatic brain injury. Complications following head trauma lead to significant acute and chronic morbidity and mortality. It is essential that clinicians be able to recognize and treat these complications in order to more effectively manage head trauma, improve outcome, and care for patients.

The release of antidiuretic hormone is appropriate in response to hypovolemia and/or sodium administration in children with severe head injury: a trial of lactated Ringer's solution versus hypertonic saline

We conducted an open, randomized, and prospective study to determine the effect of hypertonic saline on the secretion of antidiuretic hormone (ADH) and aldosterone in children with severe head injury (Glasgow coma scale <8). Thirty-one consecutive patients at a level III pediatric intensive care unit at a children's hospital received either lactated Ringer's solution (Ringer's group, n = 16) or hypertonic saline (Hypertonic Saline group, n = 15) over a 3-day period. Serum ADH levels were significantly larger in the Hypertonic Saline group as compared with the Ringer's group (P = 0.001; analysis of variance) and were correlated to sodium intake (Ringer's group: r = 0.39, R(2) = 0.15, P = 0.02; Hypertonic Saline group: r = 0.42, R(2) = 0.18, P = 0.02) and volume of fluids given IV (Ringer's group: r = 0.38, R(2) = 0.15, P = 0.02; Hypertonic Saline group: r = 0.32, R(2) = 0.1, P = not significant). Correlation of ADH to plasma osmolality was significant if plasma osmolality was >280 mOsm/kg (r = 0.5, R(2) = 0.25, P = 0.06), indicating an osmotic threshold for ADH release. Serum aldosterone levels were larger on the first day than during Days 2 and 3 in both groups and inversely correlated to serum sodium levels only in the Ringer's group (r = -0.55, R(2) = 0.3, P < 0.001). This group received a significantly larger fluid volume on Day 1 (P = 0.05, Mann-Whitney U-test) than did patients in the Hypertonic Saline group, indicating hypovolemia during the first day. Head-injured children have appropriate levels of ADH. They may be hypovolemic during the first day of treatment, especially if they receive lactated Ringer's solution.

IMPLICATIONS

In head-injured patients, we recommend fluid restriction to avoid inappropriate secretion of antidiuretic hormone. In a prospective, randomized, and controlled study in 31 children, we were able to show that the antidiuretic hormone levels are appropriate in response to hypovolemia, sodium load, or both.

Paraneoplastic syndromes in patients with laryngeal and hypopharyngeal cancers

Paraneoplastic syndromes are systemic, nonmetastatic manifestations associated with a variety of malignant neoplasms and occurring in a minority of cancer patients. Paraneoplastic syndromes in association with cancers of the larynx and hypopharynx are considered rare. The world literature is reviewed, dividing paraneoplastic syndromes into 4 main groups, ie, cutaneous (acanthosis nigricans, Bazex's syndrome, Bowen's disease, bullous pemphigoid, dermatomyositis, pruritus, Sweet's syndrome, yellow nail syndrome, and tylosis), endocrine (carcinoid syndrome, adrenocorticotropic hormone syndrome, Schwartz-Bartter syndrome, hypercalcemia), hematologic (Trousseau's syndrome), and neurologic (cerebellar degeneration, Eaton-Lambert myasthenic syndrome). A paraneoplastic syndrome may precede the clinical manifestations of a persistent or recurrent tumor or of asymptomatic metastases, and its onset may even, in a minority of cases, be the presenting sign of a malignancy. Otolaryngologists and head and neck surgeons should have a knowledge of the paraneoplastic syndromes in order to facilitate their detection of malignancies or recurrences.

Syndrome of inappropriate antidiuretic hormone secretion associated with head neck cancers: review of the literature

In a minority of patients with malignant tumors, signs and symptoms develop that cannot be explained on the basis of the mass effect produced by the primary tumor or its metastases, or production of a hormone normally associated with the tissue type that has given rise to the malignant tumor; these peculiar symptom complexes are known as paraneoplastic syndromes, and may be divided into endocrinologic, dermatologic, hematologic, neurologic, and osteoarticular manifestations. In the head and neck region in particular, the syndrome of inappropriate antidiuretic hormone production (SIADH, or Schwartz-Bartter syndrome) is a well-recognized form of paraneoplastic syndrome that may accompany head and neck malignancies. Most of such tumors are squamous carcinomas, with lesser numbers of olfactory neuroblastomas, small cell neuroendocrine carcinomas, adenoid cystic carcinomas, and undifferentiated carcinomas; sarcoma was reported in only a single instance. The lesions associated with the development of SIADH have most often been located in the oral cavity, and less often in the larynx, nasopharynx, hypopharynx, nasal cavity, maxillary sinus, parapharyngeal space, salivary glands, and oropharynx. Key features of SIADH include serum hypo-osmolality; an unexpectedly high urinary specific gravity; an absence of edema or dehydration; normal adrenal, thyroid, and renal function; hyponatremia; and an elevation of plasma vasopressin.

Fluid and electrolyte homeostasis in the elderly: physiological changes of ageing and clinical consequences

Characteristic of the normal ageing process are changes in the renal, hormonal and thirst regulatory systems involved in the control of sodium and water balance. In the presence of disease or drug use, the ageing changes put the elderly person at increased risk of either sodium retention or loss and of water retention or loss. Clinically, these alterations in water and sodium balance are commonly expressed as either hyponatraemia or hypernatraemia with central nervous system dysfunction as the symptomatic expression. Thus, the impaired homeostasis of the many systems affecting fluid balance in the elderly is readily influenced by many of the disease states and medications which are often present in the elderly with resultant adverse clinical consequences. Awareness of these age-associated circumstances can allow the physician to anticipate the impact of illnesses and drugs and to implement a rational approach to therapeutic intervention and management.

Inferior petrosal sinus sampling in healthy subjects reveals a unilateral corticotropin-releasing hormone-induced arginine vasopressin release associated with ipsilateral adrenocorticotropin secretion

Arginine vasopressin (AVP) acts synergistically with corticotropin-releasing hormone (CRH) to stimulate ACTH release from the anterior pituitary. In a previous study of bilateral simultaneous inferior petrosal sinus (IPS) sampling in healthy human subjects, we observed lateralized ACTH secretion, suggesting lateralized secretion of an ACTH-regulating hypothalamic factor. To investigate this possibility, we measured ACTH, CRH, AVP, and oxytocin (OT) levels in the IPS and the peripheral circulation in nine normal volunteers, before and after 1 microgram/kg i.v. bolus ovine CRH (oCRH). At baseline, ACTH, AVP, and OT exhibited a significant (P < 0.05) two to threefold intersinus gradient (ISG), indicating the existence of a dominant petrosal sinus. Endogenous CRH was undetectable in all samples. Despite similar exogenous oCRH levels in both petrosal sinuses, oCRH caused a significant increase (P < 0.001) in the ACTH ISG (15.8 +/- 5.6, mean +/- SEM), suggesting increased responsiveness of one dominant side of the anterior pituitary. This was associated with an ipsilateral CRH-induced AVP release and a significant increase (P < 0.01) in the AVP ISG (8.6 +/- 2.3), suggesting lateralized AVP secretion by the hypothalamus. Furthermore, the increased AVP ISG after oCRH correlated strongly with the ACTH ISG (r = 0.92, P < 0.01). oCRH administration did not affect OT. These findings suggest that there is a dominant petrosal sinus in healthy volunteers that appears to reflect a dominant side of the adenohypophysis, characterized by increased functional activity and/or responsiveness of the pituitary corticotrophs. This may reflect lateralized hypothalamic and/or suprahypothalamic function resulting in CRH-responsive lateralized secretion of AVP from parvocellular and/or magnocellular axons in the median eminence and the posterior pituitary. Although the functional and teleologic significance of these findings remains to be investigated, our data suggest a novel mechanism for CRH-mediated ACTH release, namely CRH-induced release of AVP which then enhances CRH action on the corticotrophs. Furthermore, our data represent the first direct evidence for the concept of brain lateralization with respect to neuroendocrine secretion.

Elevated arginine vasopressin levels in squamous cell cancer of the head and neck

The reported effectiveness of single tumor markers (TMs) associated with squamous cell cancer of the head and neck ranges from 15% to 71%, with most studies reporting sensitivity no higher than 50%. An increased incidence of the syndrome of inappropriate secretion of antidiuretic hormone or arginine vasopressin (SIADH) in patients with head and neck cancer has been reported. Serum arginine vasopressin (AVP) was studied as a possible TM in these patients. Sixty-three patients with squamous cell carcinoma of the head and neck determined as potentially curable were prospectively evaluated before treatment and compared to 17 patients with apparent cure of head and neck squamous cell cancer who served as controls. Serum AVP levels were obtained and determined by radioimmunoassay in the preoperative period and 1 week postoperatively in 15 patients. Thirty-four patients were staged as T4, 26 as T3, and 3 as T2. Twenty-one (33%) of the 63 patients had no neck involvement. Twenty-four (38%) of 63 patients had elevated serum AVP levels corrected for serum osmolarity. Of the 15 patients evaluated before and after surgery, 8 (53%) had elevated serum AVP levels preoperatively. Of these 8 patients, 3 had reduction in AVP levels and 5 had complete normalization after 1 week. The result obtained for serum AVP do not exceed results of other TMs reported. AVP may also not be as specific as other TMs for cancer of the head and neck. Our group with AVP sampled postoperatively is too small for us to draw conclusions, but reduction of its levels after treatment in all patients may be significant. These preliminary results indicate that further evaluation of AVP during the posttreatment course in a larger number of cases, and perhaps with other TMs as well, is warranted.

Cerebral salt wasting syndrome: a review

Hyponatremia is frequently seen in neurosurgical patients and is often attributed to inappropriate secretion of antidiuretic hormone. A number of studies in recent years have shown that hyponatremia in many patients with intracranial disease may actually be caused by cerebral salt wasting, in which a renal loss of sodium leads to hyponatremia and a decrease in extracellular fluid volume. The appropriate treatment of cerebral salt wasting fluid and salt replacement, is opposite from the usual treatment of hyponatremia caused by inappropriate secretion of antidiuretic hormone. This review summarizes the evidence in favor of cerebral salt wasting in patients with intracranial disease, examines the possible mechanisms responsible for this phenomenon, and discusses methods for diagnosis and treatment.

Gemfibrozil treatment is associated with elevated adrenal androgen, androstanediol glucuronide and cortisol levels in dyslipidemic men

We have investigated the role of steroid hormones as coronary risk factors in the Helsinki Heart Study population of dyslipidemic middle-aged men. We compare here the effects of gemfibrozil and placebo on the serum levels of dehydroepiandrosterone (DHEA), its sulfate (DHEAS), their metabolite androstanediol glucuronide (3 alpha-AdiolG), androstenedione, cortisol, testosterone, and sex-hormone binding globulin (SHBG) in non-smokers. We also examined the associations between steroid and lipoprotein levels in both treatment groups. Compared with placebo gemfibrozil treatment was associated with significant elevations of the mean levels of DHEA 10.2 vs 8.0 nmol/l; P < 0.005, of DHEAS 8.0 vs 5.8 mumol/l; P < 0.001, of 3 alpha AdiolG 18.3 vs 8.4 nmol/l; P < 0.001, of androstenedione 5.7 vs 5.1 nmol/l; P < 0.02, and of cortisol 426 vs 358 nmol/l; P < 0.001. The mean SHBG levels decreased from 46.4 to 41.7 nmol/l; P = 0.03 with gemfibrozil treatment. No difference was found in testosterone levels 17.7 vs 18.8 nmol/l; P = 0.11, or the ratio of testosterone/SHBG 0.45 vs 0.43; P = 0.23. Positive correlations were found between high density lipoprotein-cholesterol and DHEAS (r = 0.267; P < 0.01) and DHEA (r = 0.282; P < 0.01) levels and negative correlations between low density lipoprotein-cholesterol and 3 alpha-AdiolG (r = -0.400; P < 0.001) and cortisol (r = -0.281; P < 0.01) levels in the gemfibrozil group. Our results indicate that gemfibrozil treatment increases the production and turnover of adrenal androgens and cortisol, and suggest that activation of the adrenocortical function and increased metabolism of androgens are related to the improved lipoprotein pattern during gemfibrozil treatment.

Syndrome of inappropriate secretion of arginine vasopressin in patients with cancer of the head and neck

The syndrome of inappropriate secretion of arginine vasopressin (AVP) known as the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is associated with a variety of malignant and nonmalignant diseases. Only 17 cases of SIADH have been reported in the literature in association with cancer isolated to the head and neck. A retrospective review of 1,436 patients with head and neck malignancy excluding skin cancer through The University of Iowa Tumor Registry revealed 60 patients with the diagnosis of either SIADH or hyposmolality. A chart review for each of these patients was then done to establish the diagnosis of SIADH through relevant laboratory values and by excluding other causes of hyposmolality and hyponatremia. In 43 of these patients (3%), SIADH was found to be associated only with the cancer of the head and neck. We conclude that the incidence of SIADH in patients with cancer of the head and neck is much higher than previously recognized. As elevated serum AVP levels may not be clinically apparent unless associated with excessive water ingestation, it is possible that an even higher percentage of patients may have increased serum AVP levels.

Syndrome of inappropriate antidiuretic hormone secretion in cancer of the head and neck

The syndrome of inappropriate secretion of arginine vasopressin (AVP) known as the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by hyponatremia that results from water retention attributable to persistent AVP release. It may occur in a variety of malignant and nonmalignant lesions, with small cell or oat cell carcinoma of the lung by far responsible for the largest number of these cases. Cancer of the head and neck may be a rare cause of SIADH, and only a few such cases have been reported. We describe four patients with advanced cancer of the head and neck region with coexisting SIADH. Diagnosis and treatment are reported and the literature is reviewed. The possible occurrence of SIADH in the head and neck surgical practice should be kept in mind. Since SIADH is usually transient, water restriction and parenteral sodium chloride may be sufficient in overcoming the acute phase.

Hyponatremia in a neonate of a cocaine abusing mother

Neonatal hyponatremia can be caused by increased sodium losses, inadequate sodium intake, increased maternal or neonatal water load or by water retention secondary to excess of ADH release. Cocaine use by pregnant women has not as yet been reported to correlate with hyponatremia in the newborn infant. We present a case of an infant whose mother used cocaine regularly during the last stages of pregnancy and who developed hyponatremia in the first week of life. A mechanism is proposed and discussed.

Hyponatremia hypo-osmolarity in neurosurgical patients. "Appropriate secretion of ADH" and "cerebral salt wasting syndrome"

This prospective study is based on 256 patients with severe brain injury. Six patients (2.3%) developed the clinical picture of inappropriate secretion of antidiuretic hormone (SIADH): 3 in the first 3 days following the injury, 3 after more than a week. Their ADH plasmatic level were measured by radio-immunoassay. In the former, many factors, largely iatrogenic, can explain the increased secretion of ADH we found and which is then definitely "appropriate". It should be prevented by fluid restriction. In the latter, we found adequately low ADH levels, when the hypo-osmolarity is taken into account. Here, the aetiology seems to be a renal salt loss, eventually in relation to a natriuric factor (e.g. atrial natriuretic factor), justifying the term: "Cerebral salt wasting syndrome". With the resistance to fluid restriction, the treatment still remains a problem.

Relative density of urine: methods and clinical significance

The physical properties and chemical composition of urine are highly variable and are determined in large measure by the quantity and the type of food consumed. The specific gravity is the ratio of the density to that of water, and it is dependent on the number and weight of solute particles and on the temperature of the sample. The weight of solute particles is constituted mainly of urea (73%), chloride (5.4%), sodium (5.1%), potassium (2.4%), phosphate (2.0%), uric acid (1.7%), and sulfate (1.3%). Nevertheless, urine osmolality depends only on the number of solute particles. The renal production of maximally concentrated urine and formation of dilute urine may be reduced to two basic elements: (1) generation and maintenance of a renal medullary solute concentration hypertonic to plasma and (2) a mechanism for osmotic equilibration between the inner medulla and the collecting duct fluid. The interaction of the renal medullary countercurrent system, circulating levels of antidiuretic hormone, and thirst regulates water metabolism. Renin, aldosterone, prostaglandins, and kinins also play a role. Clinical estimation of the concentrating and diluting capacity can be performed by relatively simple provocative tests. However, urinary specific gravity after taking no fluids for 12 h overnight should be 1.025 or more, so that the second urine in the morning is a useful sample for screening purposes. Many preservation procedures affect specific gravity measurements. The concentration of solids (or water) in urine can be measured by weighing, hydrometer, refractometry, surface tension, osmolality, a reagent strip, or oscillations of a capillary tube. These measurements are interrelated, not identical. Urinary density measurement is useful to assess the disorders of water balance and to discriminate between prerenal azotemia and acute tubular necrosis. The water balance regulates the serum sodium concentration, therefore disorders are revealed by hypo- and hypernatremia. The disturbances are due to renal and nonrenal diseases, mainly liver, cardiovascular, intestinal, endocrine, and iatrogenic. Fluid management is an important topic of intensive care medicine. Moreover, the usefulness of specific gravity measurement of urine lies in interpreting other findings of urinalysis, both chemical and microscopical.

The syndrome of inappropriate antidiuretic hormone secretion with carcinoma of the tongue

A 64-year-old male developed symptomatic recurrent syndrome of inappropriate ADH secretion in association with locally advanced squamous cell carcinoma of the tongue. His SIADH was managed successfully with saline infusion, frusemide, and maintenance treatment with demeclocycline.

Effects of chlorpropamide on loop of Henle function and plasma renin

We have suggested that inhibition of renin release by sodium chloride is related to increased absorptive solute transport in the loop of Henle. In the rat, we have shown that reduced chloride transport in the loop is associated with increased renin release. Based on indirect evidence, it has been suggested that chlorpropamide (CPMD) increases loop solute transport. This study directly evaluates the effect of CPMD on loop chloride transport and plasma renin activity (PRA) in the male Sprague-Dawley rat. Loop of Henle chloride reabsorption (measured by recollection micropuncture) and PRA were determined before and after acute infusion of CPMD (N = 8) or vehicle (N = 8). Although delivery to the loop was not significantly changed, CPMD increased (P less than 0.05) absolute loop chloride reabsorption from 1798 pEq/min +/- 200 SE to 2453 pEq/min +/- 206 SE. PRA was decreased (P less than 0.01) from 9.2 ng/ml/hr +/- 1.0 SE to 5.6 ng/ml/hr +/- 0.8 SE following CPMD infusion. Comparable vehicle infusion did not alter loop chloride reabsorption or PRA. Arterial pressure, and whole kidney and single nephron glomerular filtration rates were unchanged following infusion of CPMD or vehicle. These results demonstrate that an increase in loop chloride reabsorption is associated with a decrease in renin release. This observation is consistent with the hypothesis that renin release is inversely related to the magnitude of chloride transport in the thick ascending limb of the loop of Henle.

Studies of vasopressin in the human cerebrospinal fluid

The development of sensitive radioimmunoassays has permitted measurement of the low concentration of vasopressin in the human cerebrospinal fluid. There is accumulating evidence to suggest that vasopressin is involved in a variety of brain functions. As an effective blood-cerebrospinal fluid barrier to vasopressin has been demonstrated, the concentration of vasopressin in the cerebrospinal fluid probably reflects the release of vasopressin within the brain. In human subjects without intracranial disease, the concentration of vasopressin in the cerebrospinal fluid is in the range 0.5-2.0 pg/ml with only little diurnal variation. Intracranial disorders associated with increased intracranial pressure may cause increased cerebrospinal fluid vasopressin concentrations, whereas degenerative brain diseases are associated with low concentrations. Only little is known about the physiologic stimuli which alter the concentration of vasopressin in cerebrospinal fluid. The concentration in cerebrospinal fluid is not influenced by a number of stimuli that cause release of vasopressin into the blood, i.e. changes in plasma osmolality, postural changes, and nausea. Elevation of the intracranial pressure, changes in the composition of the cerebrospinal fluid, electrical stimulation of the hypothalamus, and severe hemorrhage provoke an increase in cerebrospinal fluid vasopressin level.

Syndrome of inappropriate antidiuresis in Waldenström's macroglobulinemia

Hyponatremia due to the syndrome of inappropriate antidiuresis rather than due to isotonic hyponatremia from hyperproteinemia developed in a patient with Waldenström's macroglobulinemia. The patient was unable to excrete a water load normally despite suppression of antidiuretic hormone to normal levels. The temporal relationship between control of the tumor and resolution of the hyponatremia suggests that the tumor either produced a substance that enhanced the hydro-osmotic effect of endogenous antidiuretic hormone or produced an antidiuretic substance immunologically different from antidiuretic hormone. The syndrome of inappropriate antidiuresis should be suspected in hyponatremic patients with Waldenström's macroglobulinemia.