Effect of exogenous glucocorticoid on osmotically stimulated antidiuretic hormone secretion and on water reabsorption in man

The Association Between Dehydration and the Prognosis of Sudden Sensorineural Hearing Loss

Background

There is an urgent need to identify undetermined risk factors for sudden sensorineural hearing loss (SSNHL) for the development of effective treatment strategies. SSNHL is likely associated with vascular insufficiency; however, no study has evaluated the relationship between dehydration and SSNHL.

Objective

This study aimed to investigate the role of dehydration in the development and prognosis of sudden sensorineural hearing loss.

Study Design

Retrospective case-control study.

Setting

Secondary referral hospital.

Patients and Interventions

This was a comparative study that compared dehydration parameters between healthy subjects without SSNHL (n = 94) and patients with SSNHL (n = 94). The study also evaluated the effect of dehydrated conditions on the prognosis of SSNHL.

Main Outcome Measures

We compared dehydration parameters, such as the blood urea nitrogen-to-creatinine ratio (BUN/Cre) and plasma osmolality (Posm), between matched healthy subjects without SSNHL and patients with SSNHL. To evaluate the effect of dehydrated conditions on the SSNHL prognosis, the SSNHL patients were divided into 2 groups based on the cutoff value obtained from the receiver operating characteristic analysis: hydrated (n = 50; BUN/Cre <21.4) and dehydrated (n = 44; BUN/Cre ≥21.4) groups. Subsequently, the severity and prognosis of SSNHL were analyzed.

Results

The dehydration parameters, BUN/Cre and Posm, were significantly higher in patients with SSNHL than in healthy subjects. The initial hearing levels and SSNHL grades were worse in the dehydrated group than in the hydrated group. Moreover, a dehydrated condition (BUN/Cre ≥21.4) was associated with a poor SSNHL prognosis in all models of the multiple logistic regression analysis.

Conclusions

The dehydration parameters of BUN/Cre and Posm were higher in patients with SSNHL than in healthy subjects. Additionally, a dehydrated condition (BUN/Cre ≥21.4) was an independent prognostic factor for SSNHL. Level of evidence: Level 4.

Venous thromboembolism in the setting of pediatric central diabetes insipidus: a systematic review of the literature and report of 2 cases

OBJECTIVE

Central diabetes insipidus (DI) is frequently identified preoperatively and/or postoperatively in patients with sellar or parasellar lesions. Early diagnosis and effective perioperative management of central DI is critical to minimize disruptions in fluid homeostasis. In particular, although venous thromboembolism (VTE) is generally less common in pediatric patients than their adult counterparts, isolated reports suggest that VTE occurs at a higher frequency in pediatric patients with central DI.

METHODS

Using the PubMed, Scopus, and Springer Link databases, the authors performed a systematic review of the literature with regard to the incidence of VTE in pediatric patients with central DI. Inclusion criteria were availability of the full text in English, diagnosis of central DI and VTE in the same patient, and pediatric age defined as ≤ 21 years. Data were reported as median and interquartile range for continuous variables and as frequencies and percentages for categorical variables. Risk of bias assessments of the individual studies were performed using the Joanna Briggs Institute Critical Appraisal Checklists for case series and case reports.

RESULTS

Of 2094 search results, 12 articles met the inclusion criteria and described a total of 17 cases of VTE in pediatric patients with central DI. Two additional patients from the authors' institution were added to this cohort. The underlying pathologies included craniopharyngioma (n = 6), suprasellar germinoma (n = 4), epileptic encephalopathy (n = 2), pilocytic astrocytoma (n = 2), prolactinoma (n = 2), Cushing disease (n = 1), failure to thrive (n = 1), and congenital hypothalamic syndrome (n = 1). Thrombotic complications included deep vein thrombosis (n = 10 [53%]), cerebral venous sinus thrombosis (n = 6 [32%]), pulmonary embolism (n = 4 [21%]), inferior vena cava thrombosis (n = 2 [11%]), and disseminated intravascular coagulation (n = 1 [5%]). There was a 26% mortality rate.

CONCLUSIONS

VTE is a rare but potentially devastating postoperative complication that appears to have a higher incidence among patients with central DI. Although this review was limited by heterogeneous information across limited reports, pediatric neurosurgical patients with DI may benefit from more aggressive VTE surveillance and prophylaxis.

Successful treatment of hypodipsic/adipsic hypernatremia in a cat with lobar holoprosencephaly using oral desmopressin

Case summary

A 2-year-old female spayed domestic shorthair cat was presented with a history of collapse, possible hypodipsia/adipsia, severe dehydration and hypernatremia. MRI of the brain revealed a failure of separation of the cerebral hemispheres as characterized by an absence of the rostral part of the corpus callosum, fornix and septum pellucidum and the presence of a single fused lateral ventricle. A diagnosis of hypodipsic/adipsic hypernatremia with lobar holoprosencephaly was made. Dietary management of the cat's condition was attempted by increasing oral water intake, but the cat's hypernatremia and azotemia persisted. Plasma arginine vasopressin (AVP) analysis revealed a low concentration of circulating AVP (2.3 pg/ml), prompting therapy with oral desmopressin in addition to the dietary management. This combined therapy decreased water consumption of the cat from 200 ml/day (85 ml/kg/day) to 100 ml/day (30 ml/kg/day), normalized plasma sodium concentration and resolved the azotemia.

Relevance and novel information

To our knowledge, this is the second case report of an MRI diagnosis of lobar holoprosencephaly with hypodipsic/adipsic hypernatremia in a cat and the first case report of the successful management of this condition using oral desmopressin. This case report emphasizes that holoprosencephaly should be suspected in cats presented with hypodipsic/adipsic hypernatremia and highlights the utility of MRI in establishing the diagnosis. Measurements of plasma osmolality and AVP concentration corroborate the pathophysiology and support the use of oral desmopressin in addition to dietary management to resolve the hypernatremia.

Calculated plasma osmolality at hospital admission correlates well with eGFR and D-Dimer, a simple outcome predictor and guiding tool for management of severe COVID-19 patients

AIMS

To evaluate calculated total plasma osmolality as a marker of outcome prediction, fluid and metabolic balance, thrombotic risk in severe COVID-19 patients.

METHODS

Retrospective data of RT-PCR confirmed hospitalized severe COVID-19 patients (total: n = 175 patients, including diabetic subset: n = 102) were analyzed. Clinically applicable cut-offs were derived using receiver operating characteristic (ROC) curve analysis for calculated total osmolality, eGFR, and D-dimer, and their correlations were studied.

RESULTS

Among 175 severe COVID-19 patients, a significant association with mortality was seen with respect to calculated total osmolality (p < 0.001), eGFR (p < 0.001), and D-dimer (p < 0.001). In the total cohort, applicable cut-offs based on ROC curve in predicting outcome were, for total osmolality 299 mosm/kg (area under the curve (AUC)-0.773, odds ratio (OR)-1.09), eGFR 61.5 ml/min/m2 (AUC-0.789, OR-0.96), D-dimer 5.13 (AUC-0.814, OR-2.65) respectively. In diabetic subset, the cut-offs for total osmolality were 298 mosm/kg (AUC-0.794, OR-1.12), eGFR 44.9 ml/min/m2 (AUC-0.774, OR-0.96) and D-dimer 1.59 (AUC-0.769, OR-1.52) respectively.

CONCLUSIONS

Applicable cut-offs for calculated total plasma osmolality, eGFR, and D-dimer predicts clinical outcome in severe COVID-19 with and without diabetes. Correlation studies validated calculated total osmolality as a marker of the combined effect of fluid and metabolic imbalance, compromised renal function and hypercoagulability.

Effects of desmopressin acetate administration in healthy dogs receiving prednisolone

Background

Glucocorticoids are used for a variety of purposes in veterinary medicine but often are associated with clinically important adverse effects. Polyuria and polydipsia are the most frustrating adverse effects noted by owners.

Objective

To determine whether administration of desmopressin ameliorates polyuria and polydipsia associated with prednisolone administration.

Animals

Seven healthy adult Walker Hounds.

Methods

Prospective hypothesis testing study. Daily water intake and urine specific gravity (USG) were measured in dogs under 4 separate sequential conditions: no medications (C), prednisolone only (P), prednisolone and desmopressin (PD), and prednisolone after discontinuation of desmopressin (PAD).

Results

When compared to baseline, 6 of 7 dogs became polydipsic after administration of prednisolone (0.5 mg/kg PO q12h). When desmopressin (5 μg/dog SC q12h) was administered to dogs receiving prednisolone, significant decreases in water intake and serum sodium concentration occurred, and USG increased significantly.

Conclusions and Clinical Importance

Administration of desmopressin to dogs receiving prednisolone significantly decreased water intake and serum sodium concentration, and increased USG. Our results suggest that, in some dogs, desmopressin ameliorates the most important adverse effect of prednisolone noted by owners, but that hyponatremia is an important complication associated with desmopressin use.

Evaluation of dose-response effects of short-term oral prednisone administration on clinicopathologic and hemodynamic variables in healthy dogs

OBJECTIVE

To determine whether a dose-response relationship exists between short-term oral prednisone administration and common clinicopathologic variables, cardiovascular biomarkers, and systolic arterial blood pressure (SAP) in healthy dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

Dogs underwent five 5-day experiments (no prednisone treatment [control condition] and prednisone administration at 0.5, 1, 2, and 4 mg/kg, PO, q 24 h), with a 9-day washout period between protocols. Analyses performed before and after treatments included a CBC, serum biochemical analysis, and determination of SAP, fractional excretion of electrolytes, urine protein-to-creatinine ratio, glomerular filtration rate (GFR), serum N-terminal pro B-type natriuretic peptide (NT-proBNP) and plasma cortisol concentrations, and plasma renin activity. Linear mixed-effects modeling was used to compare changes in variables from baseline (day 1 for the same experiment) among treatment conditions.

RESULTS

Changes in serum glucose concentration and GFR were significantly greater after administration of prednisone at 4 mg/kg than for the control condition. Fractional excretion of sodium was decreased from baseline when dogs received 0.5, 1, or 4 mg of prednisone/kg, compared with results for the control condition. Several expected changes in clinicopathologic values were observed after prednisone administration at any dose. Changes in serum NT-proBNP concentration, plasma renin activity, and SAP did not differ from changes for the control condition at any prednisone dose.

CONCLUSIONS AND CLINICAL RELEVANCE

Oral prednisone administration did not affect SAP, NT-proBNP concentration, or measures of renin-angiotensin-aldosterone system activation in healthy laboratory-housed dogs but was associated with relative increases in GFR and serum glucose concentration.

Narrative Review of Controversies Involving Vasopressin Use in Septic Shock and Practical Considerations

Objective: To summarize literature evaluating vasopressin use, focusing on clinical controversies regarding initiation, dosing, and discontinuation and interaction of vasopressin with other therapies in septic shock patients. Data Sources: A PubMed English-language literature search (January 2008 to December 2019) was performed using these terms: arginine vasopressin, septic, shock, and sepsis. Citations, including controlled trials, observational studies, review articles, guidelines, and consensus statements, were reviewed. Study Selection and Data Extraction: Relevant clinical data focusing on specific controversial questions regarding the utility of vasopressin in patients with septic shock were narratively summarized. Data Synthesis: Current literature does not strongly support the use of vasopressin as a first-line initial therapy for septic shock. Additionally, there are conflicting data for weight-based dosing of vasopressin in overweight patients. Evidence for vasopressin renal protection and interaction with corticosteroids is minimal. However, vasopressin has the ability to reduce catecholamine requirements in septic shock patients and may provide a mortality benefit in specific subgroups. Discontinuation of vasopressin last, not second to last, in resolving septic shock may reduce hypotension development. Relevance to Patient Care and Clinical Practice: This review addresses specific clinical controversies that drive vasopressin use in septic shock patients in real-world practice. Conclusion: Vasopressin should remain second-line adjunct to norepinephrine to augment mean arterial pressures. Dosing should be initiated at 0.03 U/min, and higher doses offer minimal benefit. There are conflicting data on the impact of weight on vasopressin response. Studies have failed to show renal benefit with vasopressin use or an interaction with corticosteroid therapy.

Elevated insulin-like growth factor-1 in Cushing's disease

OBJECTIVE

To determine if patients with untreated Cushing's disease have higher serum insulin-like growth factor-1 (IGF-1) compared to matched controls, and if IGF-1 decreases following remission of Cushing's disease.

DESIGN

Retrospective case-control study matching Cushing's disease cases to control patients for adenoma size, age, sex, diabetic and gonadal status, body mass index and serum IGF-1 measured within one year. Paired analysis of pre-operative (untreated) and >3 months post-operative (remission) serum IGF-1 for cases.

PATIENTS AND MEASUREMENTS

All patients were investigated at the Princess Alexandra Hospital Endocrine Unit between 2005 and 2017. Serum IGF-1 was measured in 25 cases and 49 controls, 23 case-control pairs and 13 cases pre- and post-operatively.

RESULTS

Mean serum IGF-1 in cases was significantly higher compared to controls-32 ± 12 nmol/L compared to 25 ± 8 nmol/L, (P = 0.005). The proportion of cases with elevated serum IGF-1 above an age-adjusted reference range was higher compared to 1:1 matched controls (8/23 (35%) vs 1/23 (4%), P = 0.02). In 13 cases in remission post-operatively, serum IGF-1 decreased significantly from 31 (IQR 29-40.5) nmol/L to 23 (IQR 15-28.5) nmol/L, (P < 0.001), despite no difference in the prevalence of pre- vs post-operative pituitary hormone dysfunction (P = 0.47).

CONCLUSION

Patients with untreated Cushing's disease may have elevated IGF-1, which decreases following remission. Mildly elevated IGF-1 in Cushing's disease does not imply pathological growth hormone (GH) excess.

Refugee Status as a Possible Risk Factor for Childhood Enuresis

This study investigated the influence of refugee status on the occurrence of enuresis. It was performed among school children aged 6 to 11 years and their parents in the Vukovarsko-srijemska County (eastern Croatia), which had many displaced persons and refugees (mostly women and children) in the 1990s due to the wars in Croatia and Bosnia and Herzegovina. A specially designed questionnaire (about the child’s age and gender, the child’s enuresis history and that of the parents, and data on parental refugee status in childhood) was completed by one of the parents. Adequate data were collected for 3046 children. The prevalence of enuresis among the studied children was quite low (2.3%) but the prevalence distribution according to gender, the decline by age, and the higher odds ratio for paternal enuresis were in line with the results of other studies. The prevalence of parental enuresis in childhood was higher than their children’s enuresis (mothers: 5.8%, fathers: 3.6%, p < 0.001), and significantly higher among parents who had been refugees (mothers: p = 0.001, fathers: p = 0.04). Parental refugee status had no influence on the children’s enuresis. The results suggest that refugee status is a risk factor for the occurrence of enuresis in childhood.

Chronic Corticosterone Treatment During Adolescence Has Significant Effects on Metabolism and Skeletal Development in Male C57BL6/N Mice

Glucocorticoids are potent modulators of metabolic and behavioral function. Their role as mediators in the "stress response" is well known, but arguably their primary physiological function is in the regulation of cellular and organismal metabolism. Disruption of normal glucocorticoid function is linked to metabolic disease, such as Cushing syndrome. Glucocorticoids are also elevated in many forms of obesity, suggesting that there are bidirectional effects of these potent hormones on metabolism and metabolic function. Adolescence is a time of rapid physical growth, and disruptions during this critical time likely have important implications for adult function. The hypothalamic-pituitary-adrenal axis continues to mature during this period, as do tissues that respond to glucocorticoids. In this work, we investigate how chronic noninvasive exposure to corticosterone affects metabolic outcomes (body weight, body composition, insulin, and glucose homeostasis), as well as changes in bone density in both adult and adolescent male mice. Specifically, we report a different pattern of metabolic effects in adolescent mice compared with adults, as well as an altered trajectory of recovery in adolescents and adults. Together, these data indicate the profound influence that adolescent development has on the metabolic outcomes of chronic corticosterone exposure, and describe a tractable model for understanding the short- and long-term impacts of hypercortisolemic states on physiological and neurobehavioral functions.

Stressful Events in Early Childhood and Developmental Trajectories of Bedwetting at School Age

Objective To examine whether early stressful events are associated with developmental trajectories of bedwetting. Methods This is a prospective cohort study comprising 8,761 participants from the Avon Longitudinal Study of Parents and Children. Stressful events were measured using a maternal questionnaire completed at 3 time points before their child was 4 years old. The association between stressful events and trajectories of bedwetting from 4 to 9 years was examined using multinomial regression. Results The association with stressful events was strongest for the frequent persistent bedwetting trajectory (wetting at least twice a week up to age 9). A 1 standard deviation increase in the stressful events score was associated with a 29% (13–47%) increase in the odds of experiencing frequent persistent bedwetting compared with normal attainment of nighttime bladder control. Conclusions Clinicians and parents should be aware that continence is a developmental outcome that is associated with high levels of stress in the family.

Case report of severe Cushing's syndrome in medullary thyroid cancer complicated by functional diabetes insipidus, aortic dissection, jejunal intussusception, and paraneoplastic dysautonomia: remission with sorafenib without reduction in cortisol concentration

Background

Normalization of cortisol concentration by multikinase inhibitors have been reported in three patients with medullary thyroid cancer-related Cushing’s syndrome. Aortic dissection has been reported in three patients with Cushing’s syndrome. Diabetes insipidus without intrasellar metastasis, intestinal intussusception, and paraneoplastic dysautonomia have not been reported in medullary thyroid cancer.

Case presentation

An adult male with metastatic medullary thyroid cancer presented with hyperglycemia, hypernatremia, hypokalemia, hypertension, acne-like rash, and diabetes insipidus (urine volume >8 L/d, osmolality 190 mOsm/kg). Serum cortisol, adrenocorticoitropic hormone, dehydroepiandrostenedione sulfate, and urinary free cortisol were elevated 8, 20, 4.4, and 340 folds, respectively. Pituitary imaging was normal. Computed tomography scan revealed jejunal intussusception and incidental abdominal aortic dissection. Sorafenib treatment was associated with Cushing’s syndrome remission, elevated progesterone (>10 fold), normalization of dehydroepiandrostenedione sulfate, but persistently elevated cortisol concentration. Newly-developed proximal lower limb weakness and decreased salivation were associated with elevated ganglionic neuronal acetylcholine receptor (alpha-3) and borderline P/Q type calcium channel antibodies.

Conclusion

Extreme cortisol concentration may have contributed to aortic dissection and suppressed antidiuretic hormone secretion; which combined with hypokalemia due cortisol activation of mineralocorticoid receptors, manifested as diabetes insipidus. This is the first report of paraneoplastic dysautonomia and jejunal intussusception in medullary thyroid cancer, they may be related to medullary thyroid cancer’s neuroendocrine origin and metastasis, respectively. Remission of Cushing’s syndrome without measurable reduction in cortisol concentration suggests a novel cortisol-independent mechanism of action or assay cross-reactivity. Normalization of dehydroepiandrostenedione sulfate and elevation of progesterone suggest inhibition of 17-hydroxylase and 21-hydroxylase activities by sorafenib.

Effects of combined administration of rapamycin, tolvaptan, and AEZ-131 on the progression of polycystic disease in PCK rats

Both experimental and clinical studies have suggested that any potential treatment of polycystic kidney disease (PKD) should start early and last for a long time to be effective, with unavoidable side reactions and considerable costs. The aim of the present study was to test how low doses of rapamycin (RAPA; 0.15 mg/kg ip for 4 days/wk), tolvaptan (TOLV; 0.005% in diet), or AEZ-131 (AEZ; a novel ERK inhibitor, 30 mg/kg for 3 days/wk by gavage), alone and in association, affect the progression of polycystic renal disease in PCK rats. Rats were treated for 8 wk starting at 4-6 wk of age. The efficacy of low doses of such drugs in inhibiting their respective targets was confirmed by immunoblot experiments. Compared with rats in the control (CON) group, RAPA treatment caused a significant reduction in cyst volume density (CVD; -19% vs. the CON group) and was numerically similar to that in TOLV-treated rats (-18%, not significiant), whereas AEZ treatment was not effective. RAPA + TOLV treatment resulted in a significantly lower CVD (-49% vs. the CON group) and was associated with a striking decrease in cAMP response element-binding protein phosphorylation, and similar data were detected in RAPA + AEZ-treated rats (-42%), whereas TOLV + AEZ treatment had virtually no effect. RAPA administration significantly lessened body weight gain, whereas TOLV administration resulted a mild increase in diuresis and a significant increase in cAMP urinary excretion. Histological data of tubular proliferation were in full agreement with CVD data. In conclusion, this study demonstrates that the association of low doses of RAPA, TOLV, and AEZ slows the progression of PKD with limited side effects, suggesting the use of combined therapies also in clinical trials.

Exogenous Vasopressin-Induced Hyponatremia in Patients With Vasodilatory Shock: Two Case Reports and Literature Review

Vasopressin has gained wide support as an adjunct vasopressor in patients with septic shock. This agent exerts its vasoconstriction effects through smooth muscle V1 receptors and also has antidiuretic activity via renal V2 receptors. This interaction with the renal V2 receptors results in the integration of aquaporin 2 channels in the apical membrane of the renal collecting duct leading to free water reabsorption. Thus, water intoxication with subsequent hyponatremia, although rare, is a potentially serious side effect of exogenous vasopressin administration. We present 2 patients who developed hyponatremia within hours of initiation of vasopressin infusion. Extensive diuresis followed its discontinuation with subsequent normalization of serum sodium. One of the patients required the use of hypertonic saline for more rapid normalization of serum sodium due to concerns for potential seizure activity. A review of the literature relevant to the incidence of vasopressin-induced hyponatremia is provided as well as discussion on additional factors relevant to septic shock that should be considered when determining the relative risk of hyponatremia in patients receiving vasopressin.

Arginine vasopressin-dependent and AVP-independent mechanisms of renal fluid absorption during thirsting despite glucocorticoid-mediated vasopressin suppression

OBJECTIVE

Glucocorticoids seem to modify the release and effects of plasma arginine vasopressin (pAVP). However, underlying processes are not well understood. This study aimed to evaluate the mechanism of the modulating effects of glucocorticoids on pAVP and renal water reabsorption.

DESIGN

Fluid deprivation tests were performed without (d0) and after one (d1) and five days (d5) of oral prednisolone (Pred) pretreatment in a dosage relevant to drug therapy (30 mg/day).

PATIENTS

Twelve healthy male volunteers participated in this trial.

MEASUREMENTS

Plasma and urinary osmolality, pAVP, renin, aldosterone, plasma atrial natriuretic peptide (ANP) as well as urinary secretion of aquaporin-2 (AQP2) and prostaglandin E(2) (PGE2) were analysed.

RESULTS

An appropriate rise in pAVP was observable during thirsting (P < 0.001), which was absent after Pred pretreatment. However, the plasma and urinary osmolality after Pred treatment did not differ when compared with the basal thirsting test. Unchanged urinary AQP2 excretion suggests AVP-independent mechanisms of renal fluid reabsorption. Plasma renin concentration as well as ANP was substantially increased after Pred intake at d1 and d5 (both P < 0.05), which may mediate such AVP-independent mechanisms. Urinary PGE2 secretion was not influenced by Pred pretreatment, making a PGE2-mediated effect on renal AQP2 translocation and water permeability unlikely. Increased efficacy of exogenous desmopressin at d1 and d5 indicates also a relative increase in AVP sensitivity of the tubular cells after Pred intake.

CONCLUSIONS

The here presented data are compatible with an increased AVP sensitivity and a partially AVP-independent regulation of AQP2 translocation and renal fluid reabsorption during glucocorticoid treatment.

Hyponatremia with intracranial malignant tumor resection in children

OBJECT

Intracranial neoplasms are the second most common childhood cancer, and lead to significant morbidity and mortality. Hyponatremia is a complication associated with neurosurgical procedures, but children undergoing intracranial tumor resection have not been selectively studied. In this study, the authors aimed to determine the incidence and risk factors associated with hyponatremia among children undergoing intracranial neoplasm resection.

METHODS

A retrospective cohort was compiled using the 2006 Kids' Inpatient Database to identify children younger than 21 years of age who underwent intracranial neoplasm resection. Hyponatremia was ascertained by diagnosis codes. Bivariate analyses were conducted using chi-square and Mann-Whitney U-tests. Logistic regression models were developed to evaluate factors associated with hyponatremia in bivariate analyses.

RESULTS

Hyponatremia occurred in 205 (8.7%) of 2343 annual weighted cases, and was independently associated with tumor location in the deep brain structures and ventricles compared with the cortical area (adjusted odds ratio [aOR] 2.4; 95% CI 1.1-5.3). Hyponatremia was also associated with obstructive hydrocephalus (aOR 2.7; 95% CI 1.7-4.3) and emergency department admission (aOR 1.7; 95% CI 1.1-2.4). Hyponatremia was significantly associated with mechanical ventilation, ventriculostomy placement, ventriculoperitoneal shunt placement, and sepsis. Hyponatremia was also associated with a significantly longer average length of stay (24.6 vs 10.2 days), higher average charges ($191,000 vs $92,000), and a higher percentage of discharges to intermediate-care facilities.

CONCLUSIONS

Hyponatremia commonly occurs with resection of intracranial malignant tumors, especially for lesions located in the deep brain and in patients with obstructive hydrocephalus. Hyponatremia was associated with higher morbidity. Further research is needed to develop targeted monitoring and intervention strategies to decrease perioperative hyponatremia and to determine if this could decrease the number of complications in this specialized population.

Altered urinary excretion of aquaporin 2 in IgA nephropathy

OBJECTIVE

The intrarenal renin-angiotensin system (RAS) activation plays a pivotal role in immunoglobulin A nephropathy (IgAN) pathogenesis, which is still largely undefined. Recently, vasopressin (AVP) has been advocated to contribute to the genesis and progression of chronic kidney diseases (CKD) directly, and indirectly, via RAS activation. Our aim is to explore the intrarenal activity of AVP, its relationship with RAS activity, as well as its modulation by therapies in IgAN.

DESIGN

In this observational study, we measured plasma copeptin, a surrogate marker of AVP, the urine excretion of aquaporin 2 (AQP2), a protein reflecting renal AVP action, and angiotensinogen (AGT), a parameter of renal RAS activation, and their relationship with renal function in 44 IgAN patients at the time of renal biopsy, without any drug therapy, and after 6-month treatment with ACEi or steroid+ACEi. Twenty-one patients with other CKD and 40 healthy subjects were recruited as controls.

METHODS

ELISAs were used to measure all variables of interest.

RESULTS

At baseline, IgAN patients showed higher urinary levels of AQP2, compared with controls and patients with other CKD. Urinary AQP2 and AGT levels strongly correlated with the presence of arterial hypertension. Steroids+ACEi caused the decrease of all the variables examined. The fall of urinary AQP2 and AGT following drug treatments was associated with the decrease of daily proteinuria.

CONCLUSION

Our findings would support the involvement of AVP-AQP2 axis, interacting with the RAS, in the progression of IgAN and candidate AQP2 as a possible novel marker of the disease.

Concomitant arginine-vasopressin and hydrocortisone therapy in severe septic shock: association with mortality

PURPOSE

To evaluate the association between concomitant arginine-vasopressin (AVP)/hydrocortisone therapy and mortality in severe septic shock patients.

METHODS

This retrospective study included severe septic shock patients treated with supplementary AVP. To test the association between concomitant AVP/hydrocortisone use and mortality, a multivariate regression and Cox model (adjusted for admission year, initial AVP dosage and the Sepsis-related Organ Failure Assessment score before AVP) as well as a propensity score-based analysis were used. In both models, intensive care unit (ICU) and 28-day mortality served as outcome variables.

RESULTS

One hundred fifty-nine patients were included. Hydrocortisone was administered to 76 (47.8%) at a median daily dosage of 300 (200-300) mg. In the multivariate logistic regression model, concomitant use of AVP and hydrocortisone was associated with a trend towards lower ICU (OR, 0.51; CI 95%, 0.24-1.08; p = 0.08) and 28-day (HR, 0.69; CI 95%, 0.43-1.08; p = 0.11) mortality. The probability of survival at day 28, as predicted by the regression model, was significantly higher in patients treated with concomitant AVP and hydrocortisone compared to those receiving AVP without hydrocortisone (p = 0.001). In a propensity score-based analysis, ICU (45 vs. 65%; OR, 0.69; CI 95% 0.38-1.26; p = 0.23) and 28-day mortality (35.5 vs. 55%; OR, 0.59; CI 95%, 0.27-1.29; p = 0.18) was not different between patients treated with (n = 40) or without concomitant hydrocortisone (n = 40).

CONCLUSION

Concomitant AVP and hydrocortisone therapy may be associated with a survival benefit in septic shock. An adequately powered, randomised controlled trial appears warranted to confirm these preliminary, hypothesis-generating results.

Direct effect of methylprednisolone on renal sodium and water transport via the principal cells in the kidney

BACKGROUND

Glucocorticoids influence renal concentrating and diluting ability. We tested the hypothesis that methylprednisolone treatment increased renal water and sodium absorption by increased absorption via the aquaporin-2 (AQP2) water channels and the epithelial sodium channels (ENaCs) respectively.

METHODS

The effect of methylprednisolone was measured during fasting in a randomized, placebo-controlled, single-blinded cross-over study of 15 healthy humans. The subjects received a standardized diet on day 1, fasted on day 2, and received 500 mg methylprednisolone intravenously on day 3. The effect variables were urinary excretions of AQP2 (u-AQP2), urinary excretion of the beta-fraction of the ENaC (u-ENaC(beta)), cAMP (u-cAMP), prostaglandin E(2) (u-PGE(2)), free water clearance (C(H2O)), and fractional excretion of sodium (FE(Na)), and plasma vasopressin (p-AVP), angiotensin II (p-Ang II), aldosterone (p-Aldo), atrial natriuretic peptide (p-ANP), and brain natriuretic peptide (p-BNP).

RESULTS

Methylprednisolone treatment increased u-AQP2, u-ENaC(beta), and p-AVP significantly, but did not change u-cAMP, c(H2O), and FE(Na). P-ANP increased during methylprednisolone treatment, but after the increase in u-AQP2 and u-ENaC(beta). U-PGE(2), p-Ang II, and p-BNP were unchanged. Heart rate increased and diastolic blood pressure fell.

CONCLUSIONS

Methylprednisolone increased u-AQP2 and u-ENaC. Neither the AVP-cAMP axis nor changes in the renin-angiotensin-Aldo system, or the natriuretic peptide system seems to bear a causal relationship with the increase in either u-AQP2 or u-ENaC. Most probably, the effect is mediated via a direct effect of methylprednisolone on the principal cells. The lack of decrease in urinary output and sodium reabsorption most likely can be attributed to the diuretic and natriuretic properties of the increased secretion of ANP.

Physiology and pathophysiology of the vasopressinergic system

Arginine vasopressin, a hypothalamic peptide hormone, has multiple physiological functions, including body water regulation, control of blood pressure and effects on body temperature, insulin release, corticotropin release, memory and social behaviour. These functions are achieved via at least three specific G-protein-coupled vasopressin receptors. Development of specific vasopressin receptor antagonists in recent years is helping to elucidate the precise actions of vasopressin at each of these receptor types. The complex signalling and messenger processes which take place after receptor stimulation are now more clearly understood. Vasopressin dysregulation can occur in various disease processes, and a better understanding of the mechanisms underlying physiological synthesis, release and regulation of vasopressin will help in the development of therapies to treat these conditions.