Disorders of water and salt metabolism associated with pituitary disease

Management of potential cardiac donors

Heart transplantation (HTx) outcomes have improved with careful donor selection and management; nonetheless, donor shortages remain a major challenge. Optimizing donor management is crucial for improving donor utility rates and post-HTx outcomes. Brain death leads to various pathophysiological changes that can affect multiple organs, including the heart. Understanding these alterations and corresponding management strategies is key to optimizing the donor organ condition. This review assesses several aspects of these pathophysiological changes, including hemodynamic and endocrinological considerations, and emphasizes special consideration for potential cardiac donors, including serial echocardiographic evaluations for reversible cardiac dysfunction and coronary assessments for donors with risk factors.

Fluid Restriction Reduces Delayed Hyponatremia and Hospital Readmissions After Transsphenoidal Surgery

CONTEXT

Postoperative hyponatremia leads to prolonged hospital length of stay and readmission within 30 days.

OBJECTIVE

To assess 3 strategies for reducing rates of postoperative hyponatremia and analyze risk factors for hyponatremia.

DESIGN

Two retrospective analyses and 1 prospective study.

SETTING

Tertiary referral hospital.

PATIENTS

Patients undergoing transsphenoidal surgery for pituitary adenomas and other sellar and parasellar pathologies.

INTERVENTION(S)

Phase 1: no intervention. Phase 2: postoperative day (POD) 7 sodium testing and patient education. Phase 3: fluid restriction to 1 L/day on discharge in addition to phase 2 interventions.

MAIN OUTCOME MEASURES

Rates of early and delayed hyponatremia and readmissions. Secondary outcomes were risk factors for hyponatremia and readmission costs.

RESULTS

In phase 1, 296 patients underwent transsphenoidal surgery. Twenty percent developed early and 28% delayed hyponatremia. Thirty-eight percent underwent POD 7 sodium testing. Readmission rates were 15% overall and 4.3% for hyponatremia. In phase 2 (n = 316), 22% developed early and 25% delayed hyponatremia. Eighty-nine percent complied with POD 7 sodium testing. Readmissions were unchanged although severity of hyponatremia was reduced by 60%. In phase 3 (n = 110), delayed hyponatremia was reduced 2-fold [12.7%, relative risk (RR) = 0.52] and readmissions 3-fold [4.6%, RR = 0.30 (0.12-0.73)]; readmissions for hyponatremia were markedly reduced. Hyponatremia readmission increased costs by 30%.

CONCLUSIONS

Restricting fluid to 1 L/day on discharge decreases rates of delayed hyponatremia and readmissions by 50%. Standardized patient education and POD 7 sodium testing decreases severity of hyponatremia but does not impact readmission rates. These protocols should be considered standard practice for patients undergoing transsphenoidal surgery.

Correlation of Pituitary Descent and Diabetes Insipidus After Transsphenoidal Pituitary Macroadenoma Resection

BACKGROUND

Endoscopic transsphenoidal surgery remains the technique of choice for resection of pituitary adenoma. Postoperative diabetes insipidus (DI) is most often transient and observed in 1.6% to 34% of patients, whereas permanent DI has been reported in 0% to 2.7% of patients. The proposed mechanism was the transduction of traction forces exerted by the surgeon on the descended diaphragma sellae and through the pituitary stalk.

OBJECTIVE

To quantify and correlate the degree of pituitary gland descent with postoperative DI.

METHODS

Of 374 patients who underwent transsphenoidal resection of a pituitary adenoma between 2010 and 2020 at our institution, we report a cohort of 30 patients (Group A) DI. We also report a matched cohort by tumor volume of 30 patients who did not develop DI (Group B). We quantified the tension on the pituitary stalk by calculating pituitary descent interval (PDI) by comparing preoperative and postoperative position of the pituitary gland and using Pythagoras' formula where , with craniocaudal (CC) and anterior-posterior (AP) representing measurements of pituitary translation in respective directions after resection.

RESULTS

Patients who developed DI had significantly greater pituitary gland translations in the craniocaudal (23.0 vs 16.3 mm, P = .0015) and anteroposterior (2.4 vs 1.5 mm, P = .0168) directions. Furthermore, Group A had a statistically greater PDI, which was associated with development of DI (23.2 vs 16.6 mm, P = .0017).

CONCLUSION

We were able to quantify pituitary descent and subsequent tension on the pituitary stalk, while also associating it with development of postoperative DI after pituitary adenoma resection.

Disorders of Salt and Water Balance After Pituitary Surgery

Transsphenoidal surgery is the first-line treatment for many clinically significant pituitary tumors and sellar lesions. Although complication rates are low when performed at high-volume centers, disorders of salt and water balance are relatively common postoperatively. Both, or either, central diabetes insipidus (recently renamed arginine vasopressin deficiency - AVP-D), caused by a deficiency in production and/or secretion of arginine vasopressin, and hyponatremia, most commonly secondary to the syndrome of inappropriate antidiuresis, may occur. These conditions can extend hospital stay and increase the risk of readmission. This article discusses common presentations of salt and water balance disorders following pituitary surgery, the pathophysiology of these conditions, and their diagnosis and management.

Diagnosis and Management of Central Diabetes Insipidus in Adults

Central diabetes insipidus (CDI) is a clinical syndrome which results from loss or impaired function of vasopressinergic neurons in the hypothalamus/posterior pituitary, resulting in impaired synthesis and/or secretion of arginine vasopressin (AVP). AVP deficiency leads to the inability to concentrate urine and excessive renal water losses, resulting in a clinical syndrome of hypotonic polyuria with compensatory thirst. CDI is caused by diverse etiologies, although it typically develops due to neoplastic, traumatic, or autoimmune destruction of AVP-synthesizing/secreting neurons. This review focuses on the diagnosis and management of CDI, providing insights into the physiological disturbances underpinning the syndrome. Recent developments in diagnostic techniques, particularly the development of the copeptin assay, have improved accuracy and acceptability of the diagnostic approach to the hypotonic polyuria syndrome. We discuss the management of CDI with particular emphasis on management of fluid intake and pharmacological replacement of AVP. Specific clinical syndromes such as adipsic diabetes insipidus and diabetes insipidus in pregnancy as well as management of the perioperative patient with diabetes insipidus are also discussed.

Relationship between postoperative hypothalamic injury and water and sodium disturbance in patients with craniopharyngioma: A retrospective study of 178 cases

OBJECTIVE

To investigate the relationship between postoperative hypothalamo-hypophyseal injury (HHI) and postoperative water and sodium disturbances in patients with craniopharyngioma.

METHODS

The medical records, radiological data, and laboratory results of 178 patients (44 children and 134 adults) who underwent microsurgery for craniopharyngioma in a single center were reviewed. Postoperative HHI was assessed using magnetic resonance imaging. Structural defects of the hypothalamo-hypophyseal system (pituitary, pituitary stalk, floor and lateral wall of the third ventricle) were assessed in four standard T1-weighted images. The defect of each structure was assigned 1 score (0.5 for the unilateral injury of the third ventricle wall), and a HHI score was calculated.

RESULTS

The number of patients with HHI scores of 0-1, 2, 2.5-3, and >3 was 35, 49, 61, and 33, respectively. Diabetes insipidus (DI) worsened in 56 (31.5%) patients with preoperative DI, while 119 (66.9%) patients were diagnosed with new-onset DI. Hypernatremia and hyponatremia developed in 127 (71.3%) and 128 (71.9%) patients after surgery, respectively. Syndrome of inappropriate antidiuresis occurred in 97(54.5%) patients. During hospitalization, hypernatremia recurred in 33 (18.5%) patients and in 54 (35.7%) during follow-up, of which 18 (11.9%) were severe. DI persisted in 140 (78.7%) patients before discharge. No relationship was found between the HHI score and incidence of early DI, hyponatremia, syndrome of inappropriate diuretic hormone, or prolonged DI. Compared with patients with a score of 0-1, those with scores =2.5-3 (OR = 5.289, 95% CI:1.098-25.477, P = 0.038) and >3 (OR = 10.815, 95% CI:2.148-54.457, P = 0.004) had higher risk of developing recurrent hypernatremia. Patients with a score >3 had higher risk of developing severe hypernatremia during hospitalization (OR = 15.487, 95% CI:1.852-129.539, P = 0.011) and at follow-up (OR = 28.637, 95% CI:3.060-267.981, P = 0.003).

CONCLUSIONS

The neuroimaging scoring scale is a simple tool to semi-quantify HHI after surgery. Recurrent and severe hypernatremia should be considered in patients with a high HHI score (>2.5). An HHI score >3 is a potential predictor of adipsic DI development. Preventive efforts should be implemented in the perioperative period to reduce the incidence of potentially catastrophic complications.

Sodium and water perturbations in patients who had an acute stroke: clinical relevance and management strategies for the neurologist

Sodium and water perturbations, manifesting as hyponatraemia and hypernatraemia, are common in patients who had an acute stroke, and are associated with worse outcomes and increased mortality. Other non-stroke-related causes of sodium and water perturbations in these patients include underlying comorbidities and concomitant medications. Additionally, hospitalised patients who had an acute stroke may receive excessive intravenous hypotonic solutions, have poor fluid intake due to impaired neurocognition and consciousness, may develop sepsis or are administered drugs (eg, mannitol); factors that can further alter serum sodium levels. Sodium and water perturbations can also be exacerbated by the development of endocrine consequences after an acute stroke, including secondary adrenal insufficiency, syndrome of inappropriate antidiuretic hormone secretion and diabetes insipidus. Recently, COVID-19 infection has been reported to increase the risk of development of sodium and water perturbations that may further worsen the outcomes of patients who had an acute stroke. Because there are currently no accepted consensus guidelines on the management of sodium and water perturbations in patients who had an acute stroke, we conducted a systematic review of the literature published in English and in peer-reviewed journals between January 2000 and December 2020, according to PRISMA guidelines, to assess on the current knowledge and clinical practices of this condition. In this review, we discuss the signs and symptoms of hyponatraemia and hypernatraemia, the pathogenesis of hyponatraemia and hypernatraemia, their clinical relevance, and we provide our recommendations for effective treatment strategies for the neurologist in the management of sodium and water perturbations in commonly encountered aetiologies of patients who had an acute stroke.

Endocrine Disorder in Patients With Craniopharyngioma

Craniopharyngioma is an intracranial congenital epithelial tumor growing along the pathway of the embryonic craniopharyngeal tube. The main clinical symptoms of patients with craniopharyngioma include high intracranial pressure, visual field defect, endocrine dysfunction, and hypothalamic dysfunction. At present, the preferred treatment remains the surgical treatment, but the recovery of endocrine and hypothalamic function following surgery is limited. In addition, endocrine disorders often emerge following surgery, which seriously reduces the quality of life of patients after operation. So far, research on craniopharyngioma focuses on ways to ameliorate endocrine dysfunction. This article reviews the latest research progress on pathogenesis, manifestation, significance, and treatment of endocrine disorders in patients with craniopharyngioma.

Endocrine Management and Hormone Replacement Therapy in Cardiac Donor Management: A Retrospective Observational Study

BACKGROUND

Pituitary dysfunction after brainstem death can cause various hormone deficiencies in potential heart donors. The aim of this study was to evaluate the relationship between hormone replacement therapy (HRT; including antidiuretic hormone analog, thyroid hormone, and methylprednisolone) in heart donors and the recipients' outcomes after heart transplantation (HTx).

METHODS

We retrospectively analyzed HTxs performed between January 2012 and October 2018. Donor and recipient characteristics were retrieved with a focus on endocrine parameters and HRT. The primary outcome was primary graft dysfunction (PGD). Secondary outcomes were the 30-day and 2-year mortality of the recipients. Univariate and multivariate Cox regression analyses were applied.

RESULTS

The study included 297 HTxs. PGD occurred in 56 recipients (18.9%). In the multivariable Cox analysis, methylprednisolone and thyroxine treatment in donors were associated with a lower odds for PGD (odds ratio [OR], 0.43; 95% CI, 0.19-1.01; P = .052; and OR,: 0.34; 95% CI, 0.15-0.76; P = .009, respectively). In multivariate analysis, thyroxine treatment in donors was associated with a lower odds of PGD (OR, 0.38; 95% CI, 0.17-0.86; P = .020). Donor thyroxine supplementation also had a beneficial effect on recipients' 2-year survival (OR, 0.53; 95% CI, 0.29-0.96; P = .036).

CONCLUSIONS

Combined thyroxine and methylprednisolone treatment could be a protective factor against PGD. Thyroxine administration was associated with better 2-year survival in recipients.

Postoperative diabetes insipidus: how to define and grade this complication?

PURPOSE

Although transient diabetes insipidus (DI) is the most common complication of pituitary surgery, there is no consensus on its definition. Polyuria is the most overt symptoms of DI, but can also reflect several physiological adaptive mechanisms in the postoperative phase. These may be difficult to distinguish from and might coincide with DI. The difficulty to distinguish DI from other causes of postoperative polyuria might explain the high variation in incidence rates. This limits interpretation of outcomes, in particular complication rates between centers, and may lead to unnecessary treatment. Aim of this review is to determine a pathophysiologically sound and practical definition of DI for uniform outcome evaluations and treatment recommendations.

METHODS

This study incorporates actual data and the experience of our center and combines this with a review of literature on pathophysiological mechanisms and definitions used in clinical studies reporting of postoperative DI.

RESULTS

The occurrence of excessive thirst and/or hyperosmolality or hypernatremia are the best indicators to discriminate between pathophysiological symptoms and signs of DI and other causes. Urine osmolality distinguishes DI from osmotic diuresis.

CONCLUSIONS

To improve reliability and comparability we propose the following definition for postoperative DI: polyuria (urine production > 300 ml/hour for 3 h) accompanied by a urine specific gravity (USG) < 1.005, and at least one of the following symptoms: excessive thirst, serum osmolality > 300 mosmol/kg, or serum sodium > 145 mmol/L. To prevent unnecessary treatment with desmopressin, we present an algorithm for the diagnosis and treatment of postoperative DI.

Postoperative management of patients with pituitary tumors submitted to pituitary surgery. Experience of a Spanish Pituitary Tumor Center of Excellence

There is a lack of evidence on timing, frequency, and duration of postoperative endocrine, radiologic, and ophthalmologic assessments that should be performed after pituitary surgery (PS). However, it is known that careful optimization of treatment and follow-up strategies as well as a multidisciplinary approach may have a significant impact on long-term outcomes, improving surgical results, minimize complications and facilitate their correct treatment if occurring, and optimize the hormonal, ophthalmological, and radiological reassessment throughout the follow-up. Considering that there are no specific guidelines on the postoperative management of patients with pituitary tumors (PT), we present our protocol for the postoperative management of patients with PT. It has been elaborated by the multidisciplinary team of a Spanish Pituitary Tumor Center of Excellence (PTCE) that includes at least one neurosurgeon, ENT, neuroradiologist, neuro-ophthalmologist, endocrine pathologist and endocrinologist specialized in pituitary diseases. We elaborated this guideline with the aim of sharing our experience with other centers involved in the management of PT thereby facilitating the postoperative management of patients submitted to PS.

Diabetes insipidus

Diabetes insipidus (DI) is a disorder characterized by excretion of large amounts of hypotonic urine. Central DI results from a deficiency of the hormone arginine vasopressin (AVP) in the pituitary gland or the hypothalamus, whereas nephrogenic DI results from resistance to AVP in the kidneys. Central and nephrogenic DI are usually acquired, but genetic causes must be evaluated, especially if symptoms occur in early childhood. Central or nephrogenic DI must be differentiated from primary polydipsia, which involves excessive intake of large amounts of water despite normal AVP secretion and action. Primary polydipsia is most common in psychiatric patients and health enthusiasts but the polydipsia in a small subgroup of patients seems to be due to an abnormally low thirst threshold, a condition termed dipsogenic DI. Distinguishing between the different types of DI can be challenging and is done either by a water deprivation test or by hypertonic saline stimulation together with copeptin (or AVP) measurement. Furthermore, a detailed medical history, physical examination and imaging studies are needed to ensure an accurate DI diagnosis. Treatment of DI or primary polydipsia depends on the underlying aetiology and differs in central DI, nephrogenic DI and primary polydipsia.

Sodium Perturbations After Pituitary Surgery

Sodium perturbations are a common complication after pituitary surgery, with hyponatremia being the most frequent. Postoperative assessments should be tailored to the early and late periods, and monitoring sodium perturbations is recommended. Cerebral salt wasting is rare after pituitary surgery, and diagnosis and management can be challenging. Providing patient counseling and close postoperative follow-up is important to effectively manage diabetes insipidus and reduce hospital readmissions due to sodium perturbations.

Adipsic diabetes insipidus secondary to craniopharyngioma resection

Adipsic diabetes insipidus is an infrequent disease which may be associated with craniopharyngioma. It may be secondary to the tumour's extension, as well as to resection of the mass. We present the case of a 24-year-old woman with a history of delayed puberty and hypothyroidism, but no prior study reports. She consulted due to a headache with warning signs associated with altered visual acuity. Brain MRI was performed which showed signs of a non-adenomatous lesion with suprasellar and hypothalamic extension. Following transcranial surgery, she developed diabetes insipidus criteria, with absence of thirst documented during the hospitalisation. The histopathological findings confirmed the diagnosis of craniopharyngioma. The patient was treated with desmopressin and received recommendations regarding rehydration according to the quantification of losses, with electrolyte stabilisation.

A Copeptin-Based Approach in the Diagnosis of Diabetes Insipidus

BACKGROUND

The indirect water-deprivation test is the current reference standard for the diagnosis of diabetes insipidus. However, it is technically cumbersome to administer, and the results are often inaccurate. The current study compared the indirect water-deprivation test with direct detection of plasma copeptin, a precursor-derived surrogate of arginine vasopressin.

METHODS

From 2013 to 2017, we recruited 156 patients with hypotonic polyuria at 11 medical centers to undergo both water-deprivation and hypertonic saline infusion tests. In the latter test, plasma copeptin was measured when the plasma sodium level had increased to at least 150 mmol per liter after infusion of hypertonic saline. The primary outcome was the overall diagnostic accuracy of each test as compared with the final reference diagnosis, which was determined on the basis of medical history, test results, and treatment response, with copeptin levels masked.

RESULTS

A total of 144 patients underwent both tests. The final diagnosis was primary polydipsia in 82 patients (57%), central diabetes insipidus in 59 (41%), and nephrogenic diabetes insipidus in 3 (2%). Overall, among the 141 patients included in the analysis, the indirect water-deprivation test determined the correct diagnosis in 108 patients (diagnostic accuracy, 76.6%; 95% confidence interval [CI], 68.9 to 83.2), and the hypertonic saline infusion test (with a copeptin cutoff level of >4.9 pmol per liter) determined the correct diagnosis in 136 patients (96.5%; 95% CI, 92.1 to 98.6; P<0.001). The indirect water-deprivation test correctly distinguished primary polydipsia from partial central diabetes insipidus in 77 of 105 patients (73.3%; 95% CI, 63.9 to 81.2), and the hypertonic saline infusion test distinguished between the two conditions in 99 of 104 patients (95.2%; 95% CI, 89.4 to 98.1; adjusted P<0.001). One serious adverse event (desmopressin-induced hyponatremia that resulted in hospitalization) occurred during the water-deprivation test.

CONCLUSIONS

The direct measurement of hypertonic saline-stimulated plasma copeptin had greater diagnostic accuracy than the water-deprivation test in patients with hypotonic polyuria. (Funded by the Swiss National Foundation and others; ClinicalTrials.gov number, NCT01940614 .).

Current best practice in the management of patients after pituitary surgery

Sellar and parasellar masses are a common finding, and most of them are treated surgically via transsphenoidal approach. This type of surgery has revolutionized the approach to several hypothalamic-pituitary diseases and is usually effective, and well-tolerated by the patient. However, given the complex anatomy and high density of glandular, neurological and vascular structures in a confined space, transsphenoidal surgery harbors a substantial risk of complications. Hypopituitarism is one of the most frequent sequelae, with central adrenal insufficiency being the deficit that requires a timely diagnosis and treatment. The perioperative management of AI is influenced by the preoperative status of the hypothalamic-pituitary-adrenal axis. Disorders of water metabolism are another common complication, and they can span from diabetes insipidus, to the syndrome of inappropriate antidiuretic hormone secretion, up to the rare cerebral salt-wasting syndrome. These abnormalities are often transient, but require careful monitoring and management in order to avoid abrupt variations of blood sodium levels. Cerebrospinal fluid leaks, damage to neurological structures such as the optic chiasm, and vascular complications can worsen the postoperative course after transsphenoidal surgery as well. Finally, long-term follow up after surgery varies depending on the underlying pathology, and is most challenging in patients with acromegaly and Cushing disease, in whom failure of primary pituitary surgery is a major concern. When these pituitary functioning adenomas persist or relapse after neurosurgery other treatment options are considered, including repeated surgery, radiotherapy, and medical therapy.

Hypothalamic-pituitary sarcoidosis with vision loss and hypopituitarism: case series and literature review

PURPOSE

Hypothalamic-pituitary (HP) neurosarcoidosis (NS) accounts for 0.5 % cases of sarcoidosis and 1 % of HP masses. Correlative data on endocrine and neurological outcomes is lacking.

METHODS

Retrospective case series and literature review of presentation, treatment and outcome of HP NS.

RESULTS

Our series includes 4 men, ages 34-59, followed for a median of 7.3 years (range 1.5-17). All had optic neuropathy, multiple pituitary hormone abnormalities (PHAs) and other organ involvement by sarcoidosis (lung, sino-nasal, brain/spine and facial nerve). Two patients had central diabetes insipidus and one impaired thirst with polydipsia. After treatment with high-dose glucocorticoids, optic neuropathy improved in one case and stabilized in the others. After treatment, HP lesions improved radiologically, but PHAs persisted in all cases. Review of four published series on HP NS in addition to ours yielded 46 patients, age 37 ± 11.8 years, 65 % male. PHAs consisted of anterior hypopituitarism (LH/FSH 88.8 %, TSH 67.4 %, GH 50.0 %, ACTH 48.8 %), hyperprolactinemia (48.8 %) and diabetes insipidus (65.2 %). PHAs were the first sign of disease in 54.3 % patients. Vision problems occurred in 28.3 % patients, but optic neuropathy was not well documented in previous series. Most patients (93.5 %) received high-dose glucocorticoids followed by taper; 50 % also received other immunomodulators, including methotrexate, mycophenolate mofetil, cyclosporine, azathioprine, infliximab and hydrochloroquine. Only 13 % patients showed improvement in PHAs. All-cause mortality was 8.7 %.

CONCLUSION

HP NS is a serious disease requiring multidisciplinary treatment and lifelong follow-up. Prospective multicentric studies are needed to determine a more standardized approach to HP NS and outline predictors of disease outcome.

Pediatric anterior visual pathway gliomas: trends in fluid and electrolyte dynamics and their management nuances

PURPOSE

Trends in pre- and postoperative fluid, electrolyte and osmolarity changes, and incidence of diabetes insipidus (DI) were assessed in pediatric patients with anterior visual pathway gliomas (AVPGs).

METHODS

Thirty-three patients with AVPGs (age < 16 years) were divided into two groups: (1) no hypothalamic involvement [NHI; n = 17 (51.5 %) including optic (5, 15.2 %); chiasmal (5, 15.2 %); and optico-chiasmal (7, 21.2 %)] and (2) hypothalamic involvement [HI; n = 16 (48.5 %) including chiasmal-hypothalamic (12, 36.4 %) and optico-chiasmal-hypothalamic (4, 12.1 %)]. Frontotemporal transylvian decompression/biopsy was undertaken in 32 patients, while one patient (with severe diencephalic syndrome) was treated conservatively. Their endocrinal and fluid/electrolyte balance, serum osmolarity, and DI status were noted. Chi-square test compared clinical/endocrinological parameters, and unpaired T test evaluated mean daily water/electrolyte changes (p value < 0.05: significant).

RESULTS

Significant visual deterioration (perception of light (PL) positive (left: n = 4; right: n = 4) and PL negative (left: n = 5; right: n = 5) was encountered due to optic atrophy. Larger lesions (>3 cm), hydrocephalus [(NHI: n = 7, 41.18 %; HI: n = 12, 75 %), endocrinopathies (p = 0.047), Na(+)/K(+) derangements, and preoperative DI (n = 8, p = 0.004)] were present in the group HI. Increased postoperative urine output (almost double in those with hypothalamic involvement) and hypernatremia/hyperkalemia were seen in group HI until the sixth postoperative day (p < 0.05). Two patients with progressive hypernatremia without increased urine output showed dehydration on central venous pressure monitoring and improved with vasopressin administration. Five patients [NHI: n = 4 (23.5 %); HI: n = 1 (6.3 %)] had neurofibromatosis types I and 3 (NHI: n = 1, 5.9 %; HI: n = 2, 12.5 %) had a diencephalic syndrome.

CONCLUSIONS

Hypothalamic infiltration significantly increases the incidence of DI and fluid and electrolyte disturbances. Strict vigilance over postoperative fluid balance is mandatory during the first postoperative week. Rapidly rising serial serum sodium values without increased urine output mandates immediate central venous pressure measurement to detect DI associated with dehydration.

A systematic review of inhaled intranasal therapy for central nervous system neoplasms: an emerging therapeutic option

The intranasal route for drug delivery is rapidly evolving as a viable means for treating selected central nervous system (CNS) conditions. We aimed to identify studies pertaining to the application of intranasal drug administration for the treatment of primary CNS tumors. A systematic literature review was conducted to identify all studies published in the English language pertaining to intranasal therapy for CNS neoplasms, and/or general mechanisms and pharmacokinetics regarding targeted intranasal CNS drug delivery. A total of 194 abstracts were identified and screened. Thirty-seven studies met inclusion criteria. Of these, 21 focused on intranasal treatment of specific primary CNS tumors, including gliomas (11), meningiomas (1), and pituitary adenomas (4). An additional 16 studies focused on general mechanisms of intranasal therapy and drug delivery to the CNS using copolymer micelles, viral vectors, and nanoparticles. Inhaled compounds/substances investigated included perillyl alcohol, vesicular stomatitis virus, parvovirus, telomerase inhibitors, neural stem and progenitor cells, antimetabolites, somatostatin analogues, and dopamine agonists. Radiolabeling, CSF concentration measurement, imaging studies, and histological examination were utilized to clarify the mechanism and distribution by which drugs were delivered to the CNS. Successful drug delivery and tumor/symptom response was reported in all 21 tumor-specific studies. The intranasal route holds tremendous potential as a viable option for drug delivery for CNS neoplasms. A variety of antitumoral agents may be delivered via this route, thereby potentially offering a more direct delivery approach and ameliorating the adverse effects associated with systemic drug delivery.

Downregulation of the taurine transporter TauT during hypo-osmotic stress in NIH3T3 mouse fibroblasts

The present work was initiated to investigate regulation of the taurine transporter TauT by reactive oxygen species (ROS) and the tonicity-responsive enhancer binding protein (TonEBP) in NIH3T3 mouse fibroblasts during acute and long-term (4 h) exposure to low-sodium/hypo-osmotic stress. Taurine influx is reduced following reduction in osmolarity, keeping the extracellular Na(+) concentration constant. TonEBP activity is unaltered, whereas TauT transcription as well as TauT activity are significantly reduced under hypo-osmotic conditions. In contrast, TonEBP activity and TauT transcription are significantly increased following hyperosmotic exposure. Swelling-induced ROS production in NIH3T3 fibroblasts is generated by NOX4 and by increasing total ROS, by either exogenous application of H(2)O(2) or overexpressing NOX4, we demonstrate that TonEBP activity and taurine influx are regulated negatively by ROS under hypo-osmotic, low-sodium conditions, whereas the TauT mRNA level is unaffected. Acute exposure to ROS reduces taurine uptake as a result of modulated TauT transport kinetics. Thus, swelling-induced ROS production could account for the reduced taurine uptake under low-sodium/hypo-osmotic conditions by direct modulation of TauT.

Extralabel use of cabergoline in the treatment of a pituitary adenoma in a rat

CASE DESCRIPTION

A 0.65-kg (1.43-lb) 24-month-old sexually intact male albino pet rat was examined because of a 3-week history of hypodipsia, apparent blindness, and sudden change in behavior.

CLINICAL FINDINGS

The rat was able to move around its cage but appeared unaware of its surroundings, was visually unresponsive, and seemed unusually aggressive. The rat's hind limbs appeared mildly paretic, and it had sporadic difficulty placing its hind limbs on a flat surface. Given the rat's age, history, and physical examination findings, the primary differential diagnosis was a pituitary tumor. Magnetic resonance imaging (MRI) of the rat's brain was performed and revealed a large pituitary mass, which was indicative of a tumor.

TREATMENT AND OUTCOME

Cabergoline (0.6 mg/kg [0.27 mg/lb], PO, q 72 h) was administered. On follow-up MRI 2 months later, the pituitary mass had substantially decreased in size. For 6 months following the second MRI study, the rat continued to receive the same dosage of cabergoline and had no clinical signs of disease or unusual behavior. However, at 8.5 months after the start of the treatment, the rat was in poor condition and had clinical signs similar to those initially. A third MRI study was performed and revealed substantial regrowth of the mass. The rat was euthanized and a necropsy was performed; a histopathologic diagnosis of pituitary adenoma was made.

CLINICAL RELEVANCE

Pituitary adenomas have long been recognized as a common finding in geriatric rats (> 18 months old). Affected rats may respond favorably to oral administration of cabergoline.

Case seminar: a young female with acute hyponatremia and a sellar mass

In familial cases of combined pituitary hormone deficiency the most common mutations are that of Prophet of Pit 1 (PROP1) gene. PROP1 mutations are associated with deficiencies of growth hormone, thyrotropin, prolactin, and gonadotropins (follicle-stimulating hormone and luteinizing hormone), with evolving adrenocorticotropin (ACTH) deficiency in some cases. On imaging in most patients the pituitary gland is hypoplastic, but occasionally transient pituitary enlargement is found. We report a 22-year-old female initially diagnosed at age 12 with familial hypopituitarism due to PROP1 mutation, who presented with coma and respiratory arrest (acute hyponatremia). She was urgently treated in Intensive Care Unit of Emergency Center with hypertonic saline and stress doses of hydrocortisone, which resulted in the fast increase of plasma osmolality resulting in the osmotic demyelination syndrome. Simultaneously and incidentally on computed tomography scan a large sellar and suprasellar mass were reported as possible Rathke's cleft cyst or craniopharyngioma. Once the patient was stable, ACTH deficiency was documented. She remained replaced with hydrocortisone and subsequently underwent transphenoidal surgery. The removed sellar content revealed no pituitary adenoma or pituitary cells, but only an eosinophilic, colloid-like mass, and necrotic acellular debris. Her sister with hypopituitarism had an empty sella. Genetic testing in both sisters revealed the same homozygous c.150delA mutation in PROP1 gene. Here we report two sisters with the same PROP1 mutation who presented in adulthood with different pituitary morphology, one of them with a large sellar and suprasellar mass, in which transphenoidal surgery provided an extremely rare opportunity for a histopathological analysis of the sellar content. Due to the lack of endocrine care during the transition period hypocortisolism which evolved, a consequence of PROP1 mutation, was not recognized. Empirical use of hydrocortisone in the Intensive Care in our patient with life-threatening acute hyponatremia was appropriate but because glucocorticoid therapy on its own corrects hyponatremia even after stopping hypertonic saline infusion, the risk for over-correction of hyponatremia in ACTH deficiency is high.

Correlation of plasma copeptin and vasopressin concentrations in hypo-, iso-, and hyperosmolar States

BACKGROUND

Copeptin, the C-terminal moiety of provasopressin, is cosecreted with vasopressin. Copeptin may be a useful parameter to characterize disorders of water homeostasis and can be readily measured in plasma or serum. However, it is unknown to date how circulating copeptin and vasopressin levels correlate at different plasma osmolalites.

OBJECTIVE

To correlate plasma copeptin with plasma osmolality and vasopressin concentrations in healthy subjects during iso-, hypo-, and hyperosmolar states.

METHODS

Plasma osmolalities, copeptin, and vasopressin levels were measured in 20 volunteers at baseline, after an oral water load, and during and after iv infusion of 3% saline. Correlation coefficients were determined between plasma osmolalites and copeptin and vasopressin concentrations, as well as between vasopressin and copeptin concentrations.

RESULTS

Median plasma osmolalities decreased from 290 mOsm/kg (range, 284-302) at baseline to 281 (273-288) mOsm/kg after water load and rose to 301 (298-307) mOsm/kg after hypertonic saline. Median plasma copeptin concentrations decreased from 3.3 (1.1-36.4) pm at baseline to 2.0 (0.9-10.4) pm after water load and increased to 13.6 (3.7-43.3) pm after hypertonic saline. Vasopressin and copeptin concentrations correlated with plasma osmolality (Spearman's rank correlation coefficient 0.49 and 0.77, respectively). There was a close correlation of vasopressin and copeptin concentrations (Spearman's rank correlation coefficient 0.8).

CONCLUSION

Plasma vasopressin and copeptin correlate strongly over a wide range of osmolalities in healthy individuals. Therefore, the measurement of copeptin, which remains stable for several days, is a useful alternative to vasopressin measurements and will likely facilitate the differential diagnosis of disorders of water metabolism.

Neurobrucellosis associated with syndrome of inappropriate antidiuretic hormone with resultant diabetes insipidus and hypothyroidism

Neurological involvement of the central nervous system in brucellosis is uncommon. We describe a rare case of meningoencephalitis due to Brucella melitensis infection, associated with the syndrome of inappropriate antidiuretic hormone secretion and leading to diabetes insipidus and hypothyroidism. Neurobrucellosis, although rare, should be considered in cases of neurological disease of unknown etiology.

Water balance disorders after neurosurgery: the triphasic response revisited

Water balance disorders after neurosurgery are well recognized, but detailed reports of the triphasic response are scarce. We describe a 55-year-old woman, who developed the triphasic response with severe hyper- and hyponatraemia after resection of a suprasellar meningioma. The case illustrates how sudden and dramatic the changes in water balance after neurosurgery can be. The biochemical profile suggested central diabetes insipidus and the syndrome of inappropriate antidiuretic hormone secretion. The underlying pathophysiology was further analysed using fractional excretions, measurements of renin, aldosterone and vasopressin and a metyrapone test. Diagnostic, therapeutic and preventive strategies for these intriguing but complex cases are proposed.

The potential significance of elevated vitreous sodium levels at autopsy

Elevated levels of sodium that may be detected in the analysis of post-mortem fluid samples may arise from a wide variety of organic illnesses and environmental factors that have caused either water depletion or solute gain. When hypernatraemia is suspected at autopsy a careful history is required with particular emphasis on pre-existing medical conditions such as renal or gastrointestinal disease. In addition, detailed information is required on the circumstances of death, including any clinical symptoms and signs that the deceased may have manifested, or medical procedures such as dialysis, colonoscopy or intravenous fluid replacement. Reduced intake of fluid may be associated with cognitive or physical impairment or may result from environmental depletion (the latter may be a manifestation of inflicted injury). Both central and nephrogenic diabetes insipidus may result in the loss of excessive amounts of hypotonic fluid. This may also occur following diuretic use, or be due to gastroenteritis or burns. Hypernatraemia may be a marker of excessive salt/saline ingestion and/or administration and may occur accidentally or as a manifestation of child abuse. Given the range of possible etiologies, hypernatraemia may be a significant autopsy finding that requires explanation.

Contemporary issues in pituitary disease: case-based management update

Since 2005, the Cleveland Clinic Foundation has held an annual symposium addressing contemporary issues in pituitary disease. The faculty includes Cleveland Clinic Foundation staff, physicians and invited specialists, and the presentations are case-based with frequent audience response in order to be of real value in terms of the issues that may occur in day-to-day clinical practice relating to pituitary disease. This brief meeting report summarizes the key points arising from this interactive format. We feel it is worth pointing out that re-emphasizing 'old truths' is always an essential and valid aspect of any symposium addressing contemporary issues.