Hyponatremia: evaluating the correction factor for hyperglycemia

Management of Endocrine Emergencies in the ICU

Endocrine emergencies are frequent in critically ill patients and may be the cause of admission or can be secondary to other critical illness. The ability to anticipate endocrine abnormalities such as adrenal excess or , hypothyroidism, can mitigate their duration and severity. Hyperglycemic crisis may trigger hospital and intensive care unit (ICU) admission and may be life threatening. Recognition and safe treatment of severe conditions such as acute adrenal insufficiency, thyroid crisis, and hypoglycemia and hyperglycemic crisis may be lifesaving. Electrolyte abnormalities such as hypercalcemia and hypocalcemia may have underlying endocrine causes, and may be treated differently with recognition of those disorders- electrolyte replacement alone may not be adequate for efficient resolution. Sodium disorders are common in the ICU and are generally related to altered water balance however may be related to pituitary abnormalities in selected patients, and recognition may improve treatment effectiveness and safety.

Case report: An index of suspicion in hyponatraemia

Serum indices can give valuable information and should be interpreted as a result. Lipaemia can influence results through different mechanisms, an important one being the electrolyte exclusion effect. A case of pseudohyponatraemia due to this is reported. A 15-year-old female with type 2 diabetes was seen for follow-up. Her biochemistry results revealed severe hyponatraemia of 118 mmol/L. Her capillary glucose concentration was 13.7 mmol/L with a corrected sodium of 122 mmol/L. A lipaemic index of 3+ (absolute value 1320) was noted, which was not flagged by the laboratory information system, as it was below the critical lipaemia limit for sodium determination. Repeated analysis of the same sample using a direct ion selective electrode method, the serum sodium concentration was 134 mmol/L (sodium corrected for glucose = 138 mmol/L). A triglyceride concentration was requested, which was severely raised (100.1 mmol/L). The electrolyte exclusion effect is an analytical phenomenon that causes falsely low electrolyte concentrations in the presence of severe lipaemia or hyperproteinaemia when using indirect analytical methods. These methods are used on many modern-day automated chemistry analysers and should be considered in a patient with asymptomatic hyponatraemia.

Prognostic Role of Hyponatremia in Heart Failure Patients Depending on Renal Disease: Clinical Evidence

<b><i>Aim:</i></b> Hyponatremia is very often associated with renal disease in patients with heart failure (HF) and, when present, determines a poor outcome. We investigated the role of hyponatremia in HF patients in whom the presence or absence renal insufficiency was accurately predefined. <b><i>Methods:</i></b> This was a cohort study based on the Spanish National Registry on Heart Failure (RICA), a multicenter, prospective registry that enrolls patients admitted for decompensated HF who were subsequently followed up for 1 year. We classified patients into 4 groups according to the presence or absence of renal disease defined by the hematocrit, urea, and gender formula (HUGE) and then according to the presence of hyponatremia (Na ≤135 mEq/L). <b><i>Results:</i></b> A total of 3,478 patients were included. Hyponatremia was more prevalent in the group with renal disease (22.1%) than without (18.4%). During admission, both groups with hyponatremia had more complications than those with normal serum sodium. During the 1-year follow-up, patients with hyponatremia and renal disease had a significantly worse outcome (HF mortality and readmission), HR 1.87, 95% CI 1.54–2.29, <i>p</i> &#x3c; 0.001, compared to those with hyponatremia without renal disease, HR 1.01, 95% CI 0.79–1.3, <i>p</i> = 0.94. <b><i>Conclusions:</i></b> Hyponatremia is more prevalent in patients with renal insufficiency, and outcome is poorest when both renal disease and hyponatremia coexist. Patients with hyponatremia without renal disease show no differences in outcome compared to those without hyponatremia.

Intraoperative hyponatremia is an independent predictor of one-year mortality after liver transplantation

Preoperative hyponatremia is associated with an increased risk of mortality on the liver transplantation (LT) waiting list. We sought to investigate the impact of pre- and intraoperative serum sodium levels on the one-year mortality after LT. We identified 1,164 patients for whom preoperative and intraoperative serum sodium levels were available. Cox regression analysis with multivariable adjustment was performed for one-year mortality. A propensity score matching analysis was performed for preoperative and intraoperative serum sodium groups to compare one-year survival. The cutoff of sodium level with minimal p-value was 130 mEq/L for both preoperative and intraoperative sodium. Intraoperative hyponatremia was an independent predictor of one-year mortality in the multivariable Cox regression analysis, while preoperative hyponatremia was not. Kaplan-Meier curve showed that there was a significant difference in the one-year mortality between preoperative and intraoperative serum sodium groups. However, after propensity score matching, there was no difference in the one-year mortality among the preoperative sodium groups, while there was a significant difference among the intraoperative sodium groups. Intraoperative hyponatremia defined by mean sodium <130 mEq/L was independently associated with a significantly high one-year mortality. Mean intraoperative serum sodium levels may be a better prognostic predictor than preoperative serum sodium levels.

Development of hyponatremia in non-critical patients receiving total parenteral nutrition: A prospective, multicenter study

BACKGROUND & AIMS

Hyponatremia is frequent in hospitalized patients, especially in those receiving total parenteral nutrition (TPN). Furthermore, the presence of hyponatremia is associated with increased morbimortality in both groups. The goal of this study is to describe the prevalence of hyponatremia developing during TPN in non-critical patients, and identify risk factors for its appearance.

METHODS

This prospective multicenter study involved 19 Spanish hospitals. Noncritically-ill patients prescribed TPN over a 9-month period were studied. Variables analyzed demographic characteristics, prior comorbidities, drug therapy, PN composition, additional iv fluids, and serum sodium levels.

RESULTS

A total of 543 patients were recruited, 60.2% males. Age: 67 (IR 57-76). Of 466/543 who were eunatremic when starting TPN, 18% developed hyponatremia (serum sodium < 135 mmol/L) during TPN. Independent risk factors identified by logistic regression analysis: female (OR 1.74 [95% CI = 1.04-2.92], p = 0.036); severe malnutrition (OR 2.15 [95% CI = 1.16-4.35], p = 0.033); opiates (OR 1.97 [95% CI = 1.10-3.73], p = 0.036); and nausea/vomiting (OR 1.75 [95% CI = 1.04-2.94], p = 0.036).

CONCLUSIONS

Previously eunatremic patients frequently develop hyponatremia while receiving TPN. In this group, severe malnutrition is an independent risk factor for hyponatremia, as well as previously described risk factors: opiates, nausea/vomiting, and female gender.

Hyponatremia and the risk of kidney stones: A matched case-control study in a large U.S. health system

Kidney stones impose a large and increasing public health burden. Previous studies showed that hyponatremia is associated with an increased risk of osteoporosis and bone fractures, which are also known to be associated with kidney stones. However, the relation between hyponatremia and kidney stones is not known. To assess the relation between hyponatremia and kidney stones, we designed a matched case-control study by using the electronic health records of the MedStar Health system with more than 3.4 million unique patient records as of March 2016. Data were extracted for clinical factors of patients with kidney stones (cases) and those without kidney stones (controls). Cases (n = 20,199) and controls (n = 20,199) were matched at a 1:1 ratio for age, sex, race, and the duration of encounter window. Case and control exposures for each of the hyponatremia variables were defined by serum sodium laboratory measurements reported within the encounter windows, and divided into 3 categories: prior hyponatremia, recent hyponatremia, and persistent hyponatremia. In the final conditional logistic models adjusted for potential confounders, the risk of kidney stones significantly increased in both recent and persistent hyponatremia categories: prior hyponatremia odds ratio (OR) 0.93 (95% confidence interval [CI], 0.86–1.00); recent hyponatremia OR 2.02 (95% CI, 1.76–2.32); persistent hyponatremia OR 6.25 (95% CI, 3.27–11.96). In conclusion, chronic persistent hyponatremia is a significant and clinically important risk factor for kidney stones in patients in the U.S.

Endocrinopathy-induced euvolemic hyponatremia

Euvolemic hyponatremia results from either the syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, or adrenal insufficiency. Furthermore, the criteria for diagnosis of SIADH entail the exclusion of hypothyroidism and hypoadrenalism. We aim to assess the yield of euvolemic hyponatremia workup focusing on underlying endocrinopathies in a real-world setting. A single-center retrospective study includes all patients diagnosed with euvolemic hyponatremia in a tertiary hospital between 1.1.2007 and 1.1.2013. Demographic, clinical, and laboratory data were collected from medical charts. Euvolemic hyponatremia was detected in 564 patients. Thyroid function was tested in 69% (391/564) and adrenal function was assessed in 29% (164/564) of cases. Endocrinopathy-induced euvolemic hyponatremia was diagnosed in nine (1.6%) patients: three patients were diagnosed with hypothyroidism-induced hyponatremia, three with adrenal insufficiency as an underlying cause, and three with central hypothyroidism and central hypoadrenalism. All nine had medical history and symptoms suggestive of endocrine deficiencies other than the hyponatremia, which resolved within 1-3 days after administration of hormone replacement therapy. Yield of performed workup for hypothyroidism and hypoadrenalism in euvolemic hyponatremia was low. However, in this real-world study, only a limited number of patients underwent a full ascertainment of hypoadrenalism and hypothyroidism, which was diagnosed only in patients with additional findings supportive of these endocrinopathies; a higher rate of undiagnosed endocrinopathies cannot be ruled out. As both hypoadrenalism and hypothyroidism are easily treatable, potentially life-threatening conditions, there are insufficient data to change current recommendation for their universal evaluation in patients with euvolemic hyponatremia.

Acute Renal Failure Following Near-Drowning

Introduction

Acute kidney injury associated with near-drowning (ND-AKI) has rarely been reported and its incidence among survivors is unknown. A patient with AKI and urine biomarkers indicating tubular injury led us to assess the occurrence and clinical characteristics of ND-AKI and to evaluate possible causative mechanisms.

Methods

We evaluated medical records of patients rescued from near-drowning in the Mediterranean Sea and treated in a tertiary-level medical center during 2000 to 2017.

Results

Ninety-five patients with the diagnosis of near-drowning in seawater were treated. Forty-two of these patients (43%) developed ND-AKI and 17 (18%) were classified as AKI Kidney Disease: Improving Global Outcomes stages 2 to 3. ND-AKI was associated with the need for resuscitation and mechanical ventilation, with the calculated seawater volume ingestion (extrapolated from rising plasma sodium) and with the degree of acidemia, lactemia, and ventilatory failure. This series and 28 additional published cases of ND-AKI in the literature showed an overall male predisposition.

Conclusion

AKI is a common complication of near-drowning and is associated with increased in-hospital mortality. Data analysis suggests a predominant role of hypoxic tubular injury due to systemic hypoxemia in ND-AKI, combined with intense sympathetic activity (reflected by tachyarrhythmias, hyperglycemia, and relative hypokalemia) and increased oxygen expenditure for intensified distal tubular sodium transport. Androgen-related reduced renal vasodilatory capacity may explain male gender predominance.

Hyperglycemic Hyperosmolar State: A Pragmatic Approach to Properly Manage Sodium Derangements

INTRODUCTION

Although hypovolemia remains the most relevant problem during acute decompensated diabetes in its clinical manifestations (diabetic ketoacidosis, DKA, and hyperglycemic hyperosmolar state, HHS), the electrolyte derangements caused by the global hydroelectrolytic imbalance usually complicate the clinical picture at presentation and may be worsened by the treatment itself.

AIM

This review article is focused on the management of dysnatremias during hyperglycemic hyperosmolar state with the aim of providing clinicians a useful tool to early identify the sodium derangement in order to address properly its treatment.

DISCUSSION

The plasma sodium concentration is modified by most of the therapeutic measures commonly required in such patients and the physician needs to consider these interactions when treating HHS. Moreover, an improper management of plasma sodium concentration (PNa+) and plasma osmolality during treatment has been associated with two rare potentially life-threatening complications (cerebral edema and osmotic demyelination syndrome). Identifying the correct composition of the fluids that need to be infused to restore volume losses is crucial to prevent complications.

CONCLUSION

A quantitative approach based on the comparison between the measured PNa+ (PNa+ M) and the PNa+ expected in the presence of an exclusive water shift (PNa+ G) may provide more thorough information about the true hydroelectrolytic status of the patient and may therefore, guide the physician in the initial management of HHS. On the basis of data derived from our previous studies, we propose a 7-step algorithm to compute an accurate estimate of PNa+ G.

Hospital-Associated Hypernatremia Spectrum and Clinical Outcomes in an Unselected Cohort

BACKGROUND

Although hypernatremia is associated with adverse outcomes, most studies examined selected populations.

METHODS

Discharge data of 19,072 unselected hospitalized adults were analyzed. The crude relationship between serum sodium [Na⁺] and mortality defined hypernatremia as serum [Na⁺] >142 mEq/L. Patients with community-acquired hypernatremia or hospital-acquired hypernatremia were compared with normonatremic patients (admission [Na⁺] 138-142 mEq/L) regarding in-hospital mortality, length of stay, and discharge disposition. Patients with community-acquired hypernatremia whose hypernatremia worsened during hospitalization were compared with those without aggravation.

RESULTS

Community-acquired hypernatremia occurred in 21% of hospitalized patients and was associated with an adjusted odds ratio (OR) of 1.67 (95% confidence interval [CI], 1.38-2.01) for in-hospital mortality and 1.44 (95% CI, 1.32-1.56) for discharge to a short-/long-term care facility and an adjusted 10% (95% CI, 7-13) increase in length of stay. Hospital-acquired hypernatremia developed in 25.9% of hospitalized patients and was associated with an adjusted OR of 3.17 (95% CI, 2.45-4.09) for in-hospital mortality and 1.45 (95% CI, 1.32-1.59) for discharge to a facility, and an adjusted 49% (95% CI, 44-53) increase in length of stay. Hospital-aggravated hypernatremia developed in 11.7% of patients with community-acquired hypernatremia and was associated with greater risk of in-hospital mortality (adjusted OR, 1.84; 95% CI, 1.32-2.56) and discharge to a facility (adjusted OR, 2.14; 95% CI, 1.71-2.69), and an adjusted 16% (95% CI, 7-27) increase in length of stay.

CONCLUSIONS

The hypernatremia spectrum in unselected hospitalized patients is independently associated with increased in-hospital mortality and heightened resource consumption.

Differences in Associations of Antidepressants and Hospitalization Due to Hyponatremia

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants are important as a cause of hyponatremia. However, most studies have focused on the effect on sodium levels regardless of clinical symptoms, or have been too small to be able to discriminate between the effects of specific antidepressant drugs. The objective of the present study was to investigate the association between different groups of antidepressants and the risk of hospitalization due to hyponatremia.

METHODS

In this register-based case-control study of patients in the general Swedish population, we identified 14,359 individuals with a main diagnosis of hyponatremia. For every case, 4 matched controls were included (n = 57,382). To investigate the temporal aspects of drug-induced hyponatremia, antidepressant exposure was divided into patients with newly initiated and ongoing treatment. Univariable and multivariable logistic regression was used to analyze the association of antidepressant use and hospitalization.

RESULTS

For newly initiated antidepressants, adjusted odds ratios (95% confidence interval) for a main diagnosis of hyponatremia compared with controls were: citalopram 5.50 (4.71-6.44); sertraline 4.96 (3.81-6.48); venlafaxine 5.28 (3.20-8.83); tricyclic antidepressants 1.59 (1.13-2.24); and mirtazapine 2.54 (2.04-3.16). Adjusted odds ratio (confidence interval) for individuals with ongoing treatment ranged from 0.57 (0.52-0.63) for citalopram to 1.08 (0.85-1.36) for other SSRIs.

CONCLUSIONS

There was a strong association between newly initiated treatment with SSRIs or venlafaxine and hospitalization due to hyponatremia. The association for tricyclic antidepressants and mirtazapine was small to moderate. In contrast, there was no evidence that ongoing treatment with antidepressants increases the risk for hospitalization due to hyponatremia.

The value of venous blood gas analysis in the diagnosis of diabetic ketoacidosis

BACKGROUND & AIM

Newer blood gas analyzers have the ability to report electrolyte values and glucose in addition to pH, so this diagnostic process could be condensed in diagnosing diabetic ketoacidosis (DKA). We aimed to assess the accuracy of the venous blood gas (VBG) analysis with electrolytes for diagnosing DKA.

METHODS

This study prospectively identified a convenience sample of (60 patients) presented with DKA and tested their VBG and serum electrolytes. The diagnosis of DKA was made according to American Diabetes Association criteria. Serum chemistry electrolyte values were considered to be the criterion standard. Sensitivity and specificity of VBG electrolytes results were compared against this standard. In addition, correlation coefficients for individual electrolytes between VBG electrolytes and laboratory chemistry electrolytes were calculated.

RESULTS

Paired VBG and serum chemistry panels were available for 60 patients, only 49 patients were included, In this study; 20% of cases were newly diagnosed diabetes mellitus. The total number of diabetic ketoacidosis was 14 patients (28.5%). The sensitivity and specificity of the VBG and electrolytes for diagnosing DKA was 92.9% (95% confidence interval [CI]=89% to 99%) and 97.1% (95% CI=92% to 100%), respectively. Correlation coefficients between VBG and serum chemistry were 0.91, 0.47, 0.61, 0.65, and 0.58 for blood sugar, sodium, potassium, chloride, and creatinine respectively.

CONCLUSIONS

Findings of this study offer preliminary support for the possibility of using VBG sample rather than VBG sample and serum chemistry electrolytes together to rule out diabetic ketoacidosis.

Glargine co-administration with intravenous insulin in pediatric diabetic ketoacidosis is safe and facilitates transition to a subcutaneous regimen

BACKGROUND

Diabetes ketoacidosis (DKA) is a common presentation and complication of type 1 diabetes (T1D). While intravenous insulin is typically used to treat acute metabolic abnormalities, the transition from intravenous to subcutaneous treatment can present a challenge. We hypothesize that co-administration of glargine, a subcutaneous long-acting insulin analog, during insulin infusion may facilitate a flexible and safe transition from intravenous to subcutaneous therapy.

OBJECTIVE

To determine if the practice of administering subcutaneous glargine during intravenous insulin is associated with an increased risk of hypoglycemia, hypokalemia, or other complications in children with DKA.

METHODS

Retrospective chart review of patients aged 2 to 21 years, presenting to our center with DKA between April 2012 and June 2014. Patients were divided into two groups: those co-administered subcutaneous glargine with intravenous insulin for over 4 hours (G+); and patients with less than 2 hours of overlap (G-).

RESULTS

We reviewed 149 DKA admissions (55 G+, 94 G-) from 129 unique patients. There was a similar incidence of hypoglycemia between groups (25% G+ vs 20% G-, P = 0.46). Hypokalemia (<3.5 mmol/L) occurred more frequently in the G+ group (OR = 3.4, 95% CI 1.7-7.0, P = 0.001). Cerebral edema occurred in 2/55 (3.6%) of the G- group and none of the G+ subjects.

CONCLUSION

Co-administration of glargine early in the course of DKA treatment is well tolerated and convenient for discharge planning; however, this approach is associated with an increased risk of hypokalemia.

Managing hyponatremia in lung cancer: latest evidence and clinical implications

Hyponatremia is the most common electrolyte disorder in lung cancer patients. This condition may be related to many causes including incidental medications, concurrent diseases and side effects of antineoplastic treatments or the disease itself. Although not frequently life-threatening, it is usually associated with prolonged hospitalization, delays in scheduled chemotherapy, worsening of patient performance status and quality of life and may also negatively affect treatment response and survival. Most of the available data focus on thoracic tumors, especially small-cell lung cancer (SCLC), where hyponatremia is frequently related to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Few studies specifically focus on non-small cell lung cancer (NSCLC) patients. Hyponatremia treatment needs to be personalized based on severity and duration of sodium serum reduction, extracellular fluid volume and etiology. However, literature data highlight the importance of early correction of the serum concentration levels. To achieve this the main options are fluid restriction, hypertonic saline, loop diuretics, isotonic saline, tolvaptan and urea. The aim of this review is to analyze the role of hyponatremia in lung cancer patients, evaluating causes, diagnosis, management and clinical implications.

Hyperglycemia induces attention and gait deficits in diabetic mellitus patients

AIMS

Patients with diabetes mellitus experience a large number of falls and bone fractures that are not related solely to complications of the disease. The purpose of our study was to determine whether transient hyperglycemia affects attentional functions and gait.

METHODS

This was a case-control study. We asked 17 patients with type 1 or type 2 diabetes mellitus to perform three visual tests and one visual and auditory attention test (Phasic Alert A1-4 and A2-3, Go/No Go, Intermodal Comparison). Mean response time (ms) and total number of errors were assessed. Ten of the patients also performed a tandem gait test consisting of three steps. The total distance travelled (TDT, in mm) by the center of pressure was measured with a pressure-sensitive calibrated platform. Transient hyperglycemia was defined as blood glucose level greater than 13, 8 mmol/L at the time of the test. These same patients were retested 1-3 days later at a blood glucose level at least 5, 5 mmol/L lower than the initial values (T24-72h). Nineteen patients with diabetes mellitus were matched with the original participants and performed the same test under normoglycemic conditions.

RESULTS

During transient hyperglycemia, the mean response time (ms) and the TDT were significantly longer. The mean response time for the four tests increased by 53, 5 ms (P < 0.001). There was no increase in the number of errors. The TDT of the center of pressure increased significantly by 102 mm (P < 0.001).

CONCLUSIONS

Transient hyperglycemia alters attention and gait in patients with diabetes mellitus.

Medication-induced SIADH: distribution and characterization according to medication class

AIMS

The aims of the current study were to determine the distribution of aetiologies for the drug-induced syndrome of inappropriate antidiuretic hormone secretion (SIADH) in hospitalized patients, and to characterize them according to the different drug groups.

METHODS

A single-centre retrospective study was carried out, including all patients diagnosed with SIADH in a large community hospital and tertiary centre between 1 January 2007 and 1 January 2013 who were treated with drugs known to be associated with SIADH. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

The study cohort included 198 patients who had SIADH and received drugs associated with SIADH. Most patients [146 (73.7%)] were diagnosed with drug-associated SIADH, while 52 (26.3%) were diagnosed with SIADH due to other aetiologies. The Naranjo algorithm differentiated well between the two groups (P < 0.001). Five drug classes (antidepressants, anticonvulsants, antipsychotic agents, cytotoxic agents and pain medications) were implicated in 82.3% of patients diagnosed with drug-associated SIADH. Specific serotonin reuptake inhibitors and carbamazepine were commonly implicated. There were no clinically significant differences in the characteristics or severity of SIADH according to drug class.

CONCLUSIONS

The clinical characteristics of SIADH caused by different drugs are comparable. Patients with SIADH treated with drugs from five common medication classes will probably be diagnosed with drug-induced SIADH. Physicians should be aware of the significance of these medication classes as SIADH aetiologies.

A Quick Reference on Hyponatremia

The article focuses on causes of hyponatremia, including hypovolemia, diabetes mellitus and others. Hypovolemia is a major cause of hyponatremia in veterinary medicine. Hypovolemia causes a decrease in effective circulating volume, triggering antidiuretic hormone (ADH) secretion and free water retention, and develops after gastrointestinal losses, renal losses, hemorrhagic shock, hypoadrenocorticism, and other causes of hypovolemia. The article reviews the clinical approach to diagnosing the cause of hyponatremia in critically ill patients, including recognition of the syndrome of inappropriate ADH secretion (SIADH).

Hyperglycemia-induced hyponatremia: Reevaluation of the Na+ correction factor

This study addresses the clinically important relationship between the decreases in plasma Na⁺ and the increases in plasma glucose concentrations seen in diabetes and other hyperglycemic syndromes. This plasma 'Na⁺ correction factor', is generally accepted as 1.6mM Na⁺ per 100mg% glucose (0.29mM/mM in SI units) assuming osmotic equilibrium, although much larger numbers have been measured in experiments on normal humans. To resolve this controversy, a mathematical model of whole-body fluid-electrolyte balance was used to perform the experiment wherein plasma glucose concentration was increased to diabetic levels and the plasma Na⁺ concentration changes assessed, without the complications seen in human experiments. The findings, based on osmotic grounds, were that the factor 1) was significantly <1.6, approaching 1 in some cases, 2) depended upon the anthropometry of the subject; it was inversely proportional to the ratio of extracellular to total body water, which increases with higher fat content and 3) was approximately linear up to glucose concentrations of about 800mg%, but decreased up to 10% for higher glucose concentrations. To explain the experimental data, a hypothesis of Na⁺ sequestration in cells was incorporated in the model, resulting in close prediction of measured transient Na⁺ changes.

Prevalence of Hyponatremia and Its Associated Morbimortality in Hospitalized Patients Receiving Parenteral Nutrition

Background: The objective of the study was to determine the prevalence of hyponatremia (HN) and its associated morbimortality in hospitalized patients receiving parenteral nutrition (PN). Methods: A retrospective study including 222 patients receiving total PN (parenteral nutrition group [PNG]) over a 7-month period in a tertiary hospital and 176 matched to 179 control subjects without PN (control subjects group [CSG]). Demographic data, Charlson Comorbidity Index (CCI), date of HN detection-(serum sodium or SNa <135 mmol/L)-intrahospital mortality, and hospital length-of-stay (LOS) were registered. In the PNG, body mass index (BMI) and SNa before, during, and after PN were recorded. Results: HN was more prevalent in the PNG: 52.8 vs. 35.8% (p = 0.001), and independent of age, gender, or CCI (OR 1.8 [95% CI 1.1-2.8], p = 0.006). In patients on PN, sustained HN (75% of all intraindividual SNa <135 mmol/L) was associated with a higher mortality rate independent of age, gender, CCI, or BMI (OR 7.38 [95% CI 1.07-50.8], p = 0.042). The absence of HN in PN patients was associated with a shorter hospital LOS (<30 days) and was independent of other comorbidities (OR 3.89 [95% CI 2.11-7.18], p = 0.001). Conclusions: HN is more prevalent in patients on PN. Sustained HN is associated with a higher intrahospital mortality rate. Absence of HN is associated with a shorter hospital LOS.

Hyponatraemia - presentations and management

Hyponatraemia is the most common electrolyte disturbance encountered in clinical practice. It is associated with -significant morbidity and mortality, thus appropriate investigation and treatment is essential. Hyponatraemia presents with a spectrum of clinical presentations ranging from no symptoms to life-threatening neurological sequelae. Hyponatraemia has multiple aetiologies and distinguishing the underlying aetiology facilitates appropriate treatment. This review provides an overview of the presentations and approaches to management of this common clinical condition.

Electrolyte Disturbances in Critically Ill Cancer Patients: An Endocrine Perspective

Electrolyte disturbances are frequently encountered in critically ill oncology patients. Hyponatremia and hypernatremia as well as hypocalcemia and hypercalcemia are among the most commonly encountered electrolyte abnormalities. In the intensive care unit, management of critical electrolyte disturbances is focused on initial evaluation and immediate treatment plan to prevent severe complications. A PubMed search was performed to identify best available evidence for evaluation and management of dysnatremias, hypocalcemia, and hypercalcemia. Current literature was reviewed regarding the management of electrolyte disturbances. The role of new therapeutic options, for example, vaptans for hyponatremia, teriparatide for hypocalcemia, and denosumab for hypercalcemia, is discussed. Early diagnosis and appropriate management are expected to reduce adverse outcomes.

Efficacy and safety of rapid intermittent correction compared with slow continuous correction with hypertonic saline in patients with moderately severe or severe symptomatic hyponatremia: study protocol for a randomized controlled trial (SALSA trial)

Background

Hyponatremia is the most common electrolyte imbalance encountered in clinical practice, associated with increased mortality and length of hospital stay. However, no high-quality evidence regarding whether hypertonic saline is best administered as a continuous infusion or a bolus injection has been found to date. Therefore, in the current study, we will evaluate the efficacy and safety of rapid intermittent correction compared with slow continuous correction with hypertonic saline in patients with moderately severe or severe symptomatic hyponatremia.

Methods/design

This is a prospective, investigator-initiated, multicenter, open-label, randomized controlled study with two experimental therapy groups. A total of 178 patients with severe symptomatic hyponatremia will be enrolled and randomly assigned to receive either rapid intermittent bolus or slow continuous infusion management with hypertonic saline. The primary outcome is the incidence of overcorrection at any given period over 2 days. The secondary outcomes will include the efficacy and safety of two other approaches to the treatment of hyponatremia with 3% hypertonic saline.

Discussion

This is the first clinical trial to investigate the efficacy and safety of rapid intermittent correction compared with slow continuous correction with hypertonic saline in patients with moderately severe or severe hyponatremia.

Trial registration

ClinicalTrials.gov, identifier number: NCT02887469. Registered on 1 August 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1865-z) contains supplementary material, which is available to authorized users.

Osmotic and Hemodynamic Effects of Hypertonic Glucose During Hemodialysis

It was the purpose to quantify the hemodynamic effects of a bolus of hypertonic glucose injected into the extracorporeal system in a group of stable and nondiabetic patients during hemodialysis (HD). Glucose and electrolytes were measured in frequent intervals. Arterial blood pressures and heart rates were continuously recorded by noninvasive vascular unloading technique. Beat-to-beat stroke volume, cardiac output, and total peripheral resistance were determined by Modelflow method. Relative blood volumes were continuously measured by ultrasonic and optical means. Eight patients were studied in two treatments. Although arterial pressures and heart rates remained stable, stroke volume and cardiac output transiently increased above (19.2 ± 12.3%) and total peripheral resistance dropped below baseline (18.2 ± 8.6%) by a comparable magnitude. Relative blood volume transiently increased above baseline at 100% (104.9 ± 1.0%). Glucose concentrations were significantly related to relative blood volumes (r = 0.86, p < 0.001). In spite of a substantial increase in blood volume, a bolus of hypertonic glucose does not increase arterial pressures in nondiabetic patients because of concomitant vasodilatation. The relative increase in blood volume quantified by noninvasive HD technology follows the course of glucose and could be used as a surrogate to characterize patients with regard to their glucose metabolism during HD.

Controversies in the management of hyperglycaemic emergencies in adults with diabetes

Hyperglycaemic emergencies are associated with significant morbi-mortality and healthcare costs. Management consists on fluid replacement, insulin therapy, and electrolyte correction. However, some areas of patient management remain debatable. In patients without respiratory failure or haemodynamic instability, arterial and venous pH and bicarbonate measurements are comparable. Fluid choice varies upon replenishment phase and patient's condition. If patient is severely hypovolaemic, normal saline solution should be the first option. However, if patient has mild/moderate dehydration, fluid choice must take in consideration sodium concentration. Insulin therapy should be guided by β-hydroxybutyrate normalization and not by blood glucose. Variations of conventional insulin infusion protocols emerged recently. Priming dose of insulin may not be required, and fixed rate insulin infusion represents the best option to suppress hepatic glucose production, ketogenesis, and lipolysis. Concomitant administration of basal insulin analogues with regular insulin infusion accelerates ketoacidosis resolution and prevents rebound hyperglycaemia. Simpler protocols using subcutaneous rapid-acting insulin analogues for mild/moderate diabetic ketoacidosis treatment have proven to be safe and effective, but further studies are required to confirm these results. Treatment with bicarbonate, phosphate, and low-molecular-weight heparin is still disputable, and randomized controlled trials are urgently needed to optimize patient management and decrease the morbi-mortality of hyperglycaemic emergencies.

Long-Term Enteral Nutrition Support and the Risk of Dehydration

Dehydration is a serious risk for the long-term tube-fed patient who is not allowed oral intake, has an altered mental status, is unable to communicate, is elderly or fluid-restricted, or has thirst impairment. The intent of this review is to provide a case-based discussion regarding the evaluation, treatment, and prevention of dehydration in these types of patients. Identification of risk factors, along with evaluation of subjective, objective, and laboratory parameters, provides the basis for clinical evaluation. "Hidden" sources of fluid intake such as the water content of solid foods and water generated from nutrient oxidation and "hidden" sources of fluid output such as evaporative losses should be considered in waterbalance calculations. The method for treatment and prevention of dehydration depends on the presence or absence of hypovolemia, type of body fluid losses, and whether the patient demonstrates hypernatremia, normonatremia, or hyponatremia.

MANAGEMENT OF ENDOCRINE DISEASE: Hypothyroidism-associated hyponatremia: mechanisms, implications and treatment

BACKGROUND

Patients with moderate to severe hypothyroidism and mainly patients with myxedema may exhibit reduced sodium levels (<135 mmol/L).

SUMMARY

The aim of this short review is the presentation of the mechanisms of hyponatremia and of the available data regarding its implications and treatment in patients with hypothyroidism. Hypothyroidism is one of the causes of hyponatremia, thus thyroid-stimulating hormone determination is mandatory during the evaluation of patients with reduced serum sodium levels. The main mechanism for the development of hyponatremia in patients with chronic hypothyroidism is the decreased capacity of free water excretion due to elevated antidiuretic hormone levels, which are mainly attributed to the hypothyroidism-induced decrease in cardiac output. However, recent data suggest that the hypothyroidism-induced hyponatremia is rather rare and probably occurs only in severe hypothyroidism and myxedema. Other possible causes and superimposed factors of hyponatremia (e.g. drugs, infections, adrenal insufficiency) should be considered in patients with mild/moderate hypothyroidism. Treatment of hypothyroidism and fluid restriction are usually adequate for the management of mild hyponatremia in patients with hypothyroidism. Patients with possible hyponatremic encephalopathy should be urgently treated according to current guidelines.

CONCLUSIONS

Severe hypothyroidism may be the cause of hyponatremia. All hypothyroid patients with low serum sodium levels should be evaluated for other causes and superimposed factors of hyponatremia and treated accordingly.

Incidence of Hyponatremia with High-Dose Trimethoprim-Sulfamethoxazole Exposure

BACKGROUND

Trimethoprim-sulfamethoxazole (TMP-SMX) is a commonly prescribed antibiotic used at high doses for treatment of pneumocystis pneumonia and other infections. Trimethoprim is structurally related to the potassium-sparing diuretic amiloride and has been associated with hyperkalemia and hyponatremia through blocking of epithelial sodium channels in the distal nephron. The incidence of hyponatremia in hospitalized patients treated with high-dose TMP-SMX is unknown.

METHODS

We performed a single-center retrospective chart review of all hospitalized patients who received high-dose TMP-SMX (n = 235) from January 2012 to July 2014. Patients with congestive heart failure, cirrhosis, estimated glomerular filtration rate <30 mL/min/1.73 m², baseline hyponatremia, and those on other medications associated with hyponatremia were excluded. Hyponatremia was defined as a serum sodium level <136 mEq/L.

RESULTS

Analysis was restricted to 76 unique patients who received more than 8 mg/kg/d of TMP for ≥3 days. Mean starting serum sodium at time of TMP-SMX initiation was 138.4 ± 2.1 mEq/L. Fifty-five patients (72.3%) developed hyponatremia while on therapy, of which 43.6% (n = 24) were cases of serum sodium <130 mEq/L. Mean sodium at the time of nadir was 131.6 ± 5.1 mEq/L. Hyponatremia was noted, on average, 5.5 days after initiation of therapy, with more severe hyponatremia development among African American patients. Urine sodium concentrations were available for 40.0% (22/55) of incident hyponatremia cases, with mean urinary sodium of 104.8 ± 55.9 mEq/L. Hyponatremia often resolved within 3 weeks of drug discontinuation.

CONCLUSIONS

There is a high incidence (72.3%) of hyponatremia associated with the use of high-dose TMP-SMX among hospitalized patients. This is an overlooked and potentially reversible cause of hyponatremia.

Hyponatremia, all-cause mortality, and risk of cancer diagnoses in the primary care setting: A large population study

BACKGROUND

Hyponatremia has been associated with increased all-cause mortality in hospitalized individuals. In this study we examine the risk of all-cause mortality in primary care subjects with hyponatremia, while also exploring the association with subsequent diagnosis of cancer.

METHODS

Retrospective cohort study on subjects who underwent blood tests, consulting their general practitioner 2000-2012 in Copenhagen, Denmark. Reference range for sodium was 135-145mmol/L, and mild, moderate, and severe hyponatremia were defined as 130-135, 125-129, and <125mmol/L, respectively. Primary outcome was all-cause mortality, and secondary outcomes overall and specific types of cancer diagnoses.

RESULTS

Among 625,114 included subjects (mean age 49.9 [SD±18.4] years; 43.5% males), 90,926 (14.5%) deaths occurred. All-cause mortality was increased in mild, moderate, and severe hyponatremia (age-adjusted mortality rates [IRs, incidence rates] 26, 30, and 36 per 1000 person-years (py), respectively and incidence rate ratios [IRRs] 1.81 [95% CI: 1.76-1.85], 2.11 [2.00-2.21], and 2.52 [2.26-2.82], respectively) compared with individuals with normonatremia (IR 14 per 1000 py). For the secondary endpoint an increased level-dependent risk was found with lower sodium levels in relation to cancer overall, head and neck cancers, and pulmonary cancer, with severe hyponatremia associated with the highest IRRs (1.77 [1.39-2.24], 5.24 [2.17-12.63]), and 4.99 [3.49-7.15], respectively).

CONCLUSIONS

All levels of hyponatremia are associated with all-cause mortality in primary care patients and hyponatremia is linked to an increased risk of being diagnosed with any cancer, particularly pulmonary and head and neck cancers.

Influence of Osmolytes on In Vivo Glucose Monitoring Using Optical Coherence Tomography

Diabetes mellitus and its complications are the third leading cause of death in the world, exceeded only by cardiovascular disease and cancer. Tighter monitoring and control of blood glucose could minimize complications associated with diabetes. Recently, optical coherence tomography (OCT) for noninvasive glucose monitoring was proposed and tested in vivo. The aim of this work was to investigate the influence of changes in blood glucose concentration ([glu]) and sodium concentration ([Na+]) on the OCT signal. We also investigated the influence of other important analytes on the sensitivity of glucose monitoring with OCT. The experiments were carried out in anesthetized female pigs. The OCT images were acquired continuously from skin, while [glu] and [Na+] were experimentally varied within their physiological ranges. Correlations of the OCT signal slope with [glu] and [Na+] were studied at different tissue depths. The tissue area probed with OCT was marked and cut for histological examination. The correlation of blood [glu] and [Na+] with the OCT signal slope was observed in separate tissue layers. On average, equimolar changes in [glu] produced 2.26 ± 1.15 greater alterations of the OCT signal slope than changes in [Na+]. Variation of concentrations of other analytes did not Influence the OCT signal slope. The influence of [Na+] on relative changes in the OCT signal slope was generally less than [glu]-induced changes. OCT is a promising method for noninvasive glucose monitoring because of its ability to track the influence of changing [glu] on individual tissue layers.

The role of elevated alanine aminotransferase (ALT), FasL and atherogenic dyslipidemia in type II diabetes mellitus

Objectives

Many cross-sectional and prospective studies have shown that type 2 diabetes mellitus is a probable cause of non-alcoholic fatty liver disease (NAFLD) with fibrosis and cirrhosis. This research aimed to examine the plasma amino transaminase levels as biomarkers of NAFLD and their association with apoptosis markers (Fas and FasL) as well as the lipid profile in type II diabetic patients.

Methods

This cross-sectional comparative study included 120 type II diabetic and 100 non-diabetic patients, and their defined biomarkers were studied.

Results

The results showed that the mean ALT levels, FasL and triglyceride/high density lipoprotein (TG/HDL) ratio were significantly higher in patients with type II diabetics. According to the Atherogenic Index of Plasma (Log TG/HDL), approximately 45% of diabetic patients had a high risk and 11% had an intermediate risk of developing cardiovascular disease. Alanine aminotransferase (ALT) was significantly and positively correlated with FasL, TG, glucose levels and body mass index (BMI) in diabetic patients. Moreover, TG was positively correlated with blood glucose levels and BMI, whereas HDL was negatively correlated with FasL and ALT.

Conclusion

The results of this study showed that in diabetic patients, elevated ALT levels and FasL may play a role in the risk of developing liver disease and could be used as a distinct marker of NAFLD, indicating liver injury. Moreover, atherogenic dyslipidaemia is a prominent feature in type II diabetes mellitus. Low HDL-c is closely associated with hypertriglyceridemia with an increased risk of cardiovascular disease and NAFLD in diabetics.

Prognosis of patients with severe hyponatraemia is related not only to hyponatraemia but also to comorbidities and to medical management: results of an observational retrospective study

Background

The true cause of death in severe hyponatraemic patients remains controversial. The present study aimed to analyse the relationship between comorbidity, medical management and prognosis in severe hyponatraemic patients.

Methods

Medical records of all patients hospitalised in our institution in 2012 with a plasma sodium ≤120 mmol/l were retrospectively analysed.

Results

One hundred forty-seven of 64 723 adult patients (0.2 %) were identified with severe hyponatraemia. In-hospital mortality rate was 24.5 and 50.3 % after a median follow-up of 431 days. Patients with plasma sodium <110 mmol/l had less comorbidity (Charlson Comorbidity Index 2.2 ± 1.9 vs. 4.0 ± 3.1 (plasma sodium 110–115 mmol/l) and 4.2 ± 3.1 (plasma sodium 116–120 mmol/l); P = .02)) and a small trend for less mortality, respectively 40.0, 51.2 and 52.3 % (P = .64). At discharge, nonsurvivors and survivors had similar plasma sodium with 58.3 % of nonsurvivors being normonatraemic. Urine analysis was performed in 74.2 % of cases and associated with lower in-hospital mortality (20.2 % vs. 36.8 %, P = .05). In multivariate Cox analysis, mortality was significantly associated with plasma sodium normalisation (HR 0.35, P < 0.001), urine analysis (HR 0.48, P = .01), Charlson Comorbidity Index (HR 1.23, P < .001) and serum albumin (HR 0.88, P < .001).

Conclusion

Mortality in severe hyponatraemia appears mainly due to comorbidities although the latter are potentiated by hyponatraemia itself and its management thereby exacerbating the risk of death.

Dielectric Response of Cytoplasmic Water and Its Connection to the Vitality of Human Red Blood Cells: I. Glucose Concentration Influence

The vitality of red blood cells depends on the process control of glucose homeostasis, including the membrane's ability to "switch off" d-glucose uptake at the physiologically specific concentration of 10-12 mM. We present a comprehensive study of human erythrocytes suspended in buffer solutions with varying concentrations of d-glucose at room temperature, using microwave dielectric spectroscopy (0.5 GHz-50 GHz) and cell deformability characterization (the Elongation ratio). By use of mixture formulas the contribution of the cytoplasm to the dielectric spectra was isolated. It reveals a strong dependence on the concentration of buffer d-glucose. Tellingly, the concentration 10-12 mM is revealed as a critical point in the behavior. The dielectric response of cytoplasm depends on dipole-matrix interactions between water structures and moieties, like ATP, produced during glycolysis. Subsequently, it is a marker of cellular health. One would hope that this mechanism could provide a new vista on noninvasive glucose monitoring.

Approach to the Treatment of Diabetic Ketoacidosis

Diabetic ketoacidosis (DKA), a common cause of severe metabolic acidosis, remains a life-threatening condition due to complications of both the disease and its treatment. This Acid-Base and Electrolyte Teaching Case discusses DKA management, emphasizing complications of treatment. Because cerebral edema is the most common cause of mortality and morbidity, especially in children with DKA, we emphasize its pathophysiology and implications for therapy. The risk for cerebral edema may be minimized by avoiding a bolus of insulin, excessive saline resuscitation, and a decrease in effective plasma osmolality early in treatment. A goal of fluid therapy is to lower muscle venous Pco₂ to ensure effective removal of hydrogen ions by bicarbonate buffer in muscle and diminish the binding of hydrogen ions to intracellular proteins in vital organs (such as the brain). In patients with DKA and a relatively low plasma potassium level, insulin administration may cause hypokalemia and cardiac arrhythmias. It is suggested in these cases to temporarily delay insulin administration and first administer potassium chloride intravenously to bring the plasma potassium level close to 4mmol/L. Sodium bicarbonate administration in adult patients should be individualized. We suggest it be considered in a subset of patients with moderately severe acidemia (pH<7.20 and plasma bicarbonate level < 12mmol/L) who are at risk for worsening acidemia, particularly if hemodynamically unstable. Sodium bicarbonate should not be administered to children with DKA, except if acidemia is very severe and hemodynamic instability is refractory to saline administration.

Postoperative Care Following Pituitary Surgery

Patients undergoing surgery for pituitary tumors represent a heterogeneous population each with unique clinical, biochemical, radiologic, pathologic, neurologic, and/or ophthalmologic considerations. The postoperative management of patients following pituitary surgery often occurs in the context of a dynamic state of the hypothalamic-pituitary-end organ axis. Consequently, a significant component of the postoperative care of these patients focuses on vigilant screening and observation for neuroendocrinologic perturbations such as varying degrees of hypopituitarism and disorders of water balance (diabetes insipidus and the syndrome of inappropriate antidiuretic hormone). Additionally, one must be cognizant of other potential complications specific to the transsphenoidal approach for tumor removal including cerebrospinal fluid leakage and meningitis. This review addresses the postoperative management of patients undergoing pituitary surgery with an emphasis on careful screening and recognition of complications.

Malignancy associated SIADH: Characterization and clinical implications

PURPOSE

To determine the distribution of etiologies for the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in hospitalized patients with active malignancies and to characterize them according to the different etiologies.

METHODS

A single center retrospective study including all patients with active malignancies diagnosed with SIADH in a large community hospital and tertiary center between 1 January 2007 and 1 January 2013. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

The study cohort included 204 patients. 74.4% of those with solid tumors had metastatic disease. Most patients (149, 73%) had malignancy associated SIADH, while 55 (27%) had SIADH due to other etiologies. All of the major malignancy types were implicated in SIADH. Patients with breast cancer without lung or brain involvement were significantly less likely to be diagnosed with malignancy associated SIADH compared with other malignancies [Odds ratio (OR) 0.031, 95% CI 0.003-0.25, p < 0.001]. Patients with malignancy associated SIADH had lower serum sodium concentrations on short-term follow-up (p = 0.024) and significantly shorter median survival (58 vs. 910 days, p < 0.001). Short-term hyponatremia correction was associated with better survival.

CONCLUSIONS

SIADH is associated with most malignancy types. Physicians caring for patients with breast cancer without lung or brain involvement diagnosed with SIADH without an obvious etiology should consider obtaining lung and brain imaging to rule out undiagnosed metastatic spread. Patients with malignancy associated SIADH have considerably worse outcomes compared to cancer patient with SIADH due to other etiologies. Short-term sodium concentration can be used as a prognostic marker for these patients.

Prevalence and Prognostic Significance of Hyponatremia in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: Data from the Akershus Cardiac Examination (ACE) 2 Study

BACKGROUND

Hyponatremia is prevalent and associated with mortality in patients with heart failure (HF). The prevalence and prognostic implications of hyponatremia in acute exacerbation of chronic obstructive pulmonary (AECOPD) have not been established.

METHOD

We included 313 unselected patients with acute dyspnea who were categorized by etiology of dyspnea according to established guidelines (derivation cohort). Serum Na+ was determined on hospital admission and corrected for hyperglycemia, and hyponatremia was defined as [Na+]<137 mmol/L. Survival was ascertained after a median follow-up of 816 days and outcome was analyzed in acute HF (n = 143) and AECOPD (n = 83) separately. Results were confirmed in an independent AECOPD validation cohort (n = 99).

RESULTS

In the derivation cohort, median serum Na+ was lower in AECOPD vs. acute HF (138.5 [135.9-140.5] vs. 139.2 [136.7-141.3] mmol/L, p = 0.02), while prevalence of hyponatremia (27% [22/83] vs. 20% [29/143], p = 0.28) and mortality rate (42% [35/83] vs. 46% [66/143], p = 0.56) were similar. By univariate Cox regression analysis, hyponatremia was associated with increased mortality in acute HF (HR 1.85 [95% CI 1.08, 3.16], p = 0.02), but not in AECOPD (HR 1.00 [0.47, 2.15], p = 1.00). Analogous to the results of the derivation cohort, hyponatremia was prevalent also in the AECOPD validation cohort (25% [25/99]), but not associated with mortality. The diverging effect of hyponatremia on outcome between AECOPD and acute HF was statistically significant (p = 0.04).

CONCLUSION

Hyponatremia is prevalent in patients with acute HF and AECOPD, but is associated with mortality in patients with acute HF only.

Yield of workup for patients with idiopathic presentation of the syndrome of inappropriate antidiuretic hormone secretion

PURPOSE

To determine the proportion of patients for whom the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the presenting symptom of an underlying disorder, to describe the yield of different diagnostic modalities for patients with SIADH and an unknown etiology, and to define patients for whom such a workup is indicated.

METHODS

A single center retrospective study including all patients diagnosed with SIADH without an apparent etiology in a large community hospital and tertiary center between 1.1.07 and 1.1.13. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

Eleven of the 99 patients without an apparent etiology for SIADH at presentation were found to have an underlying cause on workup. Yield of performed workup was low, with a pathology demonstrated on 0%-30.8% of tests according to the different modalities used. Patients with presumed idiopathic SIADH at presentation who were later found to have a specific etiology were younger than patients with true idiopathic SIADH, had a significantly shorter duration of hyponatremia prior to SIADH diagnosis, had higher urine osmolality and a clinical presentation suggestive of an undiagnosed disorder.

CONCLUSIONS

Our findings support a clinically-based approach to patients with idiopathic SIADH, rather than an extensive routine workup for all patients.

Hyponatremia in Critically Ill Patients

Disorders of sodium and water metabolism are frequently encountered in hospitalized patients. Hyponatremia in critically ill patients can cause significant morbidity and mortality. Inappropriate treatment of hyponatremia can add to the problem. The diagnosis and management of salt and water abnormalities in critically ill patients is often challenging. The increasing knowledge about aquaporins and the role of vasopressin in water metabolism has enhanced our understanding of these disorders. The authors have outlined the general approach to the diagnosis and management of hyponatremia. A systematic approach by clinicians, using a detailed history, physical examination, and relevant diagnostic tests, will assist in efficient management of salt and water problems.