Diuretic-induced severe hyponatremia. Review and analysis of 129 reported patients

The Pathophysiology, Prognosis and Treatment of Hypertension in Females from Pregnancy to Post-menopause: A Review

PURPOSE OF REVIEW

We summarise the physiological changes and risk factors for hypertension in females, potential sex-specific management approaches, and long-term prognosis.

KEY FINDINGS

Pregnancy and menopause are two key phases of the life cycle where females undergo significant biological and physical changes, making them more prone to developing hypertension. Gestational hypertension occurs from changes in maternal cardiac output, kidney function, metabolism, or placental vasculature, with one in ten experiencing pregnancy complications such as intrauterine growth restriction and delivery complications such as premature birth. Post-menopausal hypertension occurs as the protective effects of oestrogen are reduced and the sympathetic nervous system becomes over-activated with ageing. Increasing evidence suggests that post-menopausal females with high blood pressure (BP) experience greater risk of cardiovascular events at lower BP thresholds, and greater vulnerability to treatment-related adverse effects. Hypertension is a key risk factor for cardiovascular disease in females. Current BP treatment guidelines and recommendations are similar for both sexes, without addressing sex-specific factors. Future investigations into ideal diagnostic thresholds, BP control targets and treatment regimens in females are needed.

Mortality predictors of patients diagnosed with severe hyponatremia in the emergency department

PURPOSE

To determine the factors affecting mortality as a result of the analysis of the demographic and clinical characteristics and laboratory parameters of patients whose serum Na value was determined to be 125 mEq/L or below at the time of admission to the emergency department (ED).

METHOD

Patients over 18 years of age who admitted to the ED of a tertiary hospital between September 2021 and September 2022 and whose serum sodium level was determined to be 125 mEq/L and below were included in the study. Demographic and clinical characteristics, admission complaints, medications used, Charles comorbidity index (CCI), laboratory parameters, and outcomes of the patients included in the study were recorded in the data form.

RESULTS

Three hundred ninety-nine patients were included in the study. When the 30-day mortality of the patients is examined, the mortality rate was found to be 21.6%. In the analyses performed for the predictive power of laboratory parameters for mortality, it was determined that the highest predictive power among the predictive values determined by the area under the curve (AUC) was the albumin level (AUC 0.801, 95% CI 0.753-0.849, p < 0.001). In the binary logistic regression analysis, urea and albumin were independent predictors of 30-day mortality.

CONCLUSION

According to study data, albumin and urea levels are independent predictors of 30-day mortality in patients diagnosed with severe hyponatremia in the emergency department.

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

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

Cumulative Incidence of Thiazide-Induced Hyponatremia : A Population-Based Cohort Study

BACKGROUND

According to drug labels, the frequency of thiazide-induced hyponatremia is unknown or uncommon to very rare (that is, <1 in 10 000 to <1 in 100), but the exact burden remains unclear.

OBJECTIVE

To estimate the increase in the cumulative incidence of hyponatremia using thiazide diuretics compared with nonthiazide antihypertensive drugs in routine clinical practice.

DESIGN

Population and register-based cohort study using target trial emulation.

SETTING

Denmark, 1 January 2014 to 31 October 2018.

PARTICIPANTS

Two target trials were emulated among persons aged 40 years or older who had no recent prescription for any antihypertensive drug, had no previous hyponatremia, and were eligible for the studied antihypertensive treatments. The first target trial emulation compared new use of bendroflumethiazide (BFZ) versus a calcium-channel blocker (CCB). The second target trial emulation compared new use of hydrochlorothiazide plus a renin-angiotensin system inhibitor (HCTZ-RASi; that is, combination pill) versus a RASi alone.

MEASUREMENTS

Two-year cumulative incidences of sodium levels less than 130 mmol/L using stabilized inverse probability of treatment-weighted survival curves.

RESULTS

The study compared 37 786 new users of BFZ with 44 963 of a CCB and 11 943 new users of HCTZ-RASi with 85 784 of a RASi. The 2-year cumulative incidences of hyponatremia were 3.83% for BFZ and 3.51% for HCTZ-RASi. The risk differences were 1.35% (95% CI, 1.04% to 1.66%) between BFZ and CCB and 1.38% (CI, 1.01% to 1.75%) between HCTZ-RASi and RASi; risk differences were higher with older age and higher comorbidity burden. The respective hazard ratios were 3.56 (CI, 2.76 to 4.60) and 4.25 (CI, 3.23 to 5.59) during the first 30 days since treatment initiation and 1.26 (CI, 1.09 to 1.46) and 1.29 (CI, 1.05 to 1.58) after 1 year.

LIMITATION

The study assumed that filled prescriptions equaled drug use, and residual confounding is likely.

CONCLUSION

Treatment initiation with thiazide diuretics suggests a more substantial excess risk for hyponatremia, particularly during the first months of treatment, than indicated by drug labeling.

PRIMARY FUNDING SOURCE

Independent Research Fund Denmark.

Frequency and Severity of Chlorothiazide-Induced Hyponatremia in the Neonatal Intensive Care Unit

OBJECTIVE

Although thiazide diuretics are commonly used in the neonatal intensive care unit (NICU), the risk of thiazide-induced hyponatremia in infants has not been well documented. The primary objective of this study was to determine the frequency and severity of hyponatremia in neonates and infants receiving enteral chlorothiazide. Secondary objectives included identifying: (1) percent change in serum sodium from before chlorothiazide initiation to nadir, (2) time to reach nadir serum sodium concentration, and (3) percentage of patients on chlorothiazide receiving sodium supplementation.

STUDY DESIGN

This was a retrospective cohort study of NICU patients admitted between July 1, 2014, and July 31, 2019, who received ≥1 dose of enteral chlorothiazide. Mild, moderate, and severe hyponatremia were defined as serum sodium of 130 to 134 mEq/L, 120 to 129 mEq/L, and less than 120 mEq/L, respectively. Data including serum electrolytes, chlorothiazide dosing, and sodium supplementation were collected for the first 2 weeks of therapy. Descriptive and inferential statistics were performed in SAS software, Version 9.4.

RESULTS

One hundred and seven patients, receiving 127 chlorothiazide courses, were included. The median gestational age at birth and postmenstrual age at initiation were 26.0 and 35.9 weeks, respectively. The overall frequency of hyponatremia was 35.4% (45/127 courses). Mild, moderate, and severe hyponatremia were reported in 27 (21.3%), 16 (12.6%), and 2 (1.6%) courses. The median percent decrease in serum sodium from baseline to nadir was 2.9%, and the median time to nadir sodium was 5 days. Enteral sodium supplements were administered in 52 (40.9%) courses. Sixteen courses (12.6%) were discontinued within the first 14 days of therapy due to hyponatremia.

CONCLUSION

Hyponatremia occurred in over 35% of courses of enteral chlorothiazide in neonates and infants. Given the high frequency of hyponatremia, serum sodium should be monitored closely in infants receiving chlorothiazide. Providers should consider early initiation of sodium supplements if warranted.

KEY POINTS

· One-third of infants on chlorothiazide develop hyponatremia.. · Nadir serum sodium typically occurs within 5 days.. · Monitor sodium closely after chlorothiazide initiation..

Approach to the Patient: Hyponatremia and the Syndrome of Inappropriate Antidiuresis (SIAD)

Hyponatremia is the most common electrolyte disturbance seen in clinical practice, affecting up to 30% of acute hospital admissions, and is associated with significant adverse clinical outcomes. Acute or severe symptomatic hyponatremia carries a high risk of neurological morbidity and mortality. In contrast, chronic hyponatremia is associated with significant morbidity including increased risk of falls, osteoporosis, fractures, gait instability, and cognitive decline; prolonged hospital admissions; and etiology-specific increase in mortality. In this Approach to the Patient, we review and compare the current recommendations, guidelines, and literature for diagnosis and treatment options for both acute and chronic hyponatremia, illustrated by 2 case studies. Particular focus is concentrated on the diagnosis and management of the syndrome of inappropriate antidiuresis. An understanding of the pathophysiology of hyponatremia, along with a synthesis of the duration of hyponatremia, biochemical severity, symptomatology, and blood volume status, forms the structure to guide the appropriate and timely management of hyponatremia. We present 2 illustrative cases that represent common presentations with hyponatremia and discuss the approach to management of these and other causes of hyponatremia.

Diuretic therapy in congestive heart failure

In heart failure, fluid overload is a major pathological mechanism leading to vascular congestion, pulmonary congestion and elevated jugular venous pressures. Diuretics play a significant role in the management of patients with congestive heart failure. It is used to relieve the congestive symptoms of heart failure. However, the appropriate use of diuretics remains challenging due to various complications like electrolyte abnormalities, worsening renal function and diuretic resistance. This has prompted towards the search of safer and effective alternatives. This review evaluates the use of diuretics in congestive heart failure and discusses the complications of different types of diuretics, which is essential for successful management of congestion in patients with heart failure and hence to optimise the outcome for the patients.

Prospective determination of the incidence and severity of hyponatraemia in older hospitalised patients with acute urinary tract obstruction

INTRODUCTION

acute urinary tract obstruction (aUTO) is a common finding in older hospitalised patients. Anecdotal reports described hyponatraemia in patients with aUTO, which subsides rapidly with relief of the obstruction.The aim of this study was to determine the incidence, severity and subsequent correction of hyponatraemia in patients with aUTO.

METHODS

this is a prospective, single-centre, observational study including inpatients in the internal medicine and geriatric wards. A total of 204 patients were investigated, 104 with aUTO and 100 controls. The prevalence, severity and associations of hyponatraemia between aUTO and control patients were compared.

RESULTS

the incidence of hyponatraemia was similar in aUTO and control groups 28% versus 22%, respectively (P = 0.42). However, the incidence of severe hyponatraemia was significantly higher in the study group 7% versus 1% (P = 0.04). Mean sodium level was lower in hyponatremic patients with aUTO 127.7 ± 5.9 mEq/l versus 130.8 ± 3 mEq/l (P = 0.013). Serum sodium remained largely unchanged in the control group (∆Na 1.5 ± 2.3 mEq/l) but increased significantly within 48 hours following catheter insertion in patients with urinary retention (∆Na 5.3 ± 4.2 mEq/l overall in the aUTO group and 9.6 ± 3 mEq/l in those with urinary retention and severe hyponatraemia (P = 0.002)).

Non-thiazide diuretics and hospitalization due to hyponatraemia: A population-based case-control study

OBJECTIVE

Diuretics are often implicated in hyponatraemia. While thiazides constitute one of the most common causes of hyponatraemia, data on loop diuretics and potassium-sparing agents are limited and partly conflicting. The objective of this investigation was to study the association between use of different types of non-thiazide diuretics and hospitalization due to hyponatraemia.

DESIGN, PATIENTS AND MEASUREMENTS

This was a register-based case-control study on the adult Swedish population. By linking national registers, patients hospitalized with a principal diagnosis of hyponatraemia (n = 11,213) from 1 October 2005 through 31 December 2014 were compared with matched controls (n = 44,801). Multivariable logistic regression, adjusted for multiple confounders, was used to analyse the association between use of diuretics and hyponatraemia. In addition, newly initiated use (≤90 days) and ongoing use were examined separately.

RESULTS

Adjusted odds ratios (aORs) (95% CI) were 0.61 (0.57-0.66) for the use of furosemide, 1.69 (1.54-1.86) for the use of amiloride and 1.96 (1.78-2.18) for the use of spironolactone and hospitalization due to hyponatraemia. For newly initiated therapy, aORs ranged from 1.23 (1.04-1.47) for furosemide to 3.55 (2.75-4.61) for spironolactone. The aORs for ongoing use were 0.52 (0.47-0.57) for furosemide, 1.62 (1.47-1.79) for amiloride and 1.75 (1.56-1.98) for spironolactone.

CONCLUSIONS

Ongoing use of furosemide was inversely correlated with hospitalization due to hyponatraemia, suggesting a protective effect. Consequently, if treatment with furosemide precedes the development of hyponatraemia by some time, other causes of hyponatraemia should be sought. Spironolactone and amiloride may both contribute to hyponatraemia; this effect is most prominent early in treatment.

Association between newly initiated thiazide diuretics and hospitalization due to hyponatremia

Purpose

Thiazide diuretics are the most common origin of drug-induced hyponatremia. However, population-based studies on clinical outcomes are lacking. We therefore explored the time course and absolute risk of thiazide-associated hospitalization due to hyponatremia in Sweden.

Methods

Population-based case-control study including patients hospitalized with a principal diagnosis of hyponatremia (n = 11,213) compared with controls (n = 44,801). Linkage of registers was used to acquire data. Multivariable regression was applied to explore time-dependent associations between thiazide diuretics and hospitalization due to hyponatremia. Attributable risks were calculated assessing the disease burden attributable to thiazides.

Results

Individuals initiating thiazide treatment were exposed to an immediate increase in risk for hospitalization with adjusted odds ratio (aOR) (95% CI) of 48 (28–89). The associations gradually declined reaching an aOR of 2.9 (2.7–3.1) for individuals treated for longer than 13 weeks. The attributable risk of hyponatremia-associated hospitalization due to thiazides of any treatment length was 27% (3095/11,213). Among 806 patients initiating treatment < 90 days before hospitalization, hyponatremia could be attributed to thiazides in 754. Based on nationwide data, 616,678 individuals were initiated on thiazides during the 8-year study period suggesting an absolute risk of 0.12% (754/661,678) for subsequent hospitalization with a main diagnosis of hyponatremia.

Conclusions

Thiazide diuretics attributed to more than one in four individuals hospitalized due to hyponatremia. The risk increase was very pronounced during the first month of treatment and then gradually declined, without returning to normal. However, the absolute risk for the development of hyponatremia demanding hospitalization may for most individuals be modest.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-020-03086-6.

Severe hyponatremia with seizures and confirmed mild brain edema by hysteroscopic myomectomy: a case report

BACKGROUND

Hyponatremia can be developed during hysteroscopic surgery with electrolyte-free irrigation fluid. We experienced severe hyponatremia with postoperative seizures and confirmed mild brain edema.

CASE PRESENTATION

A quadragenarian female patient underwent a 2-h hysteroscopic myomectomy with electrolyte-free fluid for uterine distension under general anesthesia. Plasma sodium level of 84.1 mmol/L 100 min after the start of surgery indicated excessive absorption of the irrigation fluid. Acute severe hyponatremia was diagnosed with significant edema in the conjunctiva, lip, and extremities. She was treated with a continuous infusion of hypertonic saline. However, seizures and cerebral edema developed 7 h later. The patient recovered without neurological deficits at postoperative day 2.

CONCLUSION

The electrolyte-free irrigation fluid can be absorbed rapidly during hysteroscopic surgery. Its interruption with hyponatremia should be considered against prolonged surgery. Especially under general anesthesia, caution should be exercised because the typical symptoms of hyponatremia such as nausea and confusion are blinded.

Development of a hyponatremia screening tool (ABCDF-S score) for patients with hypertension using thiazide diuretic agents

WHAT IS KNOWN AND OBJECTIVE

Hyponatremia is a common side effect of thiazide diuretics that can lead to increased mortality and hospitalization. A rapid and accurate screening tool is needed for rapid and appropriate management. In this study, we report on the development of a simple clinical screening tool for hyponatremia using thiazide diuretics.

METHODS

This nested case-control study was performed by collecting data from 1 January 2015 to 30 June 2017. Univariable and multivariable logistic regressions were used to identify potential risk factors. The regression coefficients were converted into item scores by dividing each regression coefficient with the minimum coefficient in the model and rounding to the nearest integer. This value was then summed to the total score. The prediction power of the model was determined by the area under the receiver operating characteristic curve (AuROC).

RESULTS AND DISCUSSION

Six clinical risk factors, namely age ≥65 years, benzodiazepine use, history of a cerebrovascular accident, dose of hydrochlorothiazide ≥25 mg, female sex and statin use, were included in our ABCDF-S score. The model showed good power of prediction (AuROC 81.53%, 95% confidence interval [CI]: 78%-84%) and good calibration (Hosmer-Lemeshow X²  = 23.20; P = .39). The positive likelihood ratios of hyponatremia in patients with low risk (score ≤ 6) and high risk (score ≥ 8) were 0.26 (95% CI: 0.21-0.32) and 3.89 (95% CI: 3.11-4.86), respectively.

WHAT IS NEW AND CONCLUSION

The screening tool with six risk predictors provided a useful prediction index for thiazide-associated hyponatremia. However, further validation of the tool is warranted prior to its utilization in routine clinical practice.

Role of Risk Factors in Developing Osmotic Demyelination Syndrome During Correction of Hyponatremia: A Case Study

This case report describes a 57-year-old man who presented first with lethargy and dysarthria due to hyponatremia resulting from poor intake and diuretics. One week after discharge, he returned with confusion, ataxia and dysphagia, and he ultimately turned out to have developed an osmotic demyelination syndrome (ODS). In his first hospital admission, his serum sodium was corrected without new neurological symptoms occurring. In retrospect, he had several risk factors for the development of ODS during the correction of hyponatremia. The serum sodium correction rate only briefly exceeded the recommended limits. This case underlines that (1) extra awareness of the serum sodium correction rate is warranted in patients with risk factors, (2) factors other than sodium can play an important role in the development of ODS and (3) that the manifestations of ODS can be delayed substantially after an incident of osmotic stress.

Prevalence and incidence of hyponatremia and their association with diuretic therapy: Results from North India

Introduction:

Hyponatremia is associated with substantial morbidity and mortality. Correct estimation of their prevalence, incidence and risk factors, especially the diuretics in Indian patients is important in determining preventive strategies.

Methods:

This multistage mixed methods-based study was conducted in a high-volume cardiac care center to ensure the correct estimation. Patients receiving oral diuretics on an outpatient basis and those admitted to hospital for hyponatremia were enrolled.

Results:

The prevalence of hyponatremia was 27% while the incidence rate was 18% and 29% after 3- and 6-month of the diuretic therapy. The highest rates of hyponatremia were observed in warm season (45%, 111 in 247 patients). Multivariate logistic regression analysis revealed that low solute and nutritious intake and edematous state were negatively correlated with serum sodium levels. Neither diarrhea/vomiting nor diuretic use were found to be associated with hyponatremia.

Conclusions:

Diuretics use was not associated with hyponatremia in adults in this population cohort. However, elderly people on diuretics are comparatively more likely to have hyponatremia. However, a randomized parallel arm trial comparing diuretics with other antihypertensives be done to establish whether diuretics are associated with hyponatremia in this patient population.

Seasonal variation in the prevalence of profound hyponatremia (<125 mmol/l) in patients on admission to an acute hospital in Japan

Hyponatremia is a common but important electrolyte disorder mostly complicated with other diseases. Recently, we experienced a case of a hypertensive patient in her seventies taking a thiazide diuretic, who presented with disorientation due to severe hyponatremia (serum sodium level, 104 mmol/l) on admission. Taking this opportunity, patients with profound hyponatremia (<125 mmol/l) on admission were investigated. Patients newly admitted to Matsumoto Medical Center (an acute hospital) were surveyed retrospectively for one year from May 1, 2016 to April 30, 2017. Patients with profound hyponatremia on admission were selected, and their clinical characteristics were evaluated. A total of 108 out of 4223 patients (2.6%; 67 men, 41 women) showed profound hyponatremia, and 101 out of 108 patients were 65 years old and over. The prevalence of profound hyponatremia in the warm season of April to October (3.1%, 76 in 2444 patients) was significantly ( p = 0.002, χ2 test) higher than that in the cold season of November to March (1.8%, 32 in 1779 patients). The monthly prevalence tended to correlate with the monthly average temperature of the local area ( r = 0.517, p = 0.085). There were six patients treated with thiazide diuretics in the warm season, while there were no such patients in the cold season, not reaching a significant difference ( p = 0.240). The present study demonstrated an increased risk of hyponatremia in elderly patients during the warm season. Considering also the relevant literature, health professionals should pay enough attention to thiazide- or drug-induced hyponatremia and the impact of water/salt intake for heat exposure.

Misconceptions and Barriers to the Use of Hypertonic Saline to Treat Hyponatremic Encephalopathy

Hyponatremic encephalopathy is a potentially life-threatening condition with a high associated morbidity and mortality. It can be difficult to diagnose as the presenting symptoms can be non-specific and do not always correlate with the degree of hyponatremia. It can rapidly progress leading to death from transtentorial herniation. Hypertonic saline is the recommended treatment for hyponatremic encephalopathy, whether acute or chronic, yet it is infrequently used. We believe that the main barriers to its use is the perception that hypertonic saline is associated with a significant risk for cerebral demyelination, that it can't be administered through a peripheral IV and that it requires monitoring in the ICU. Two illustrative cases are presented followed by a discussion of how intermittent bolus's of 100−150 ml of 3% NaCl in rapid succession to acutely increase the plasma sodium by 4−6 mEq/L is a safe and effective way to treat hyponatremic encephalopathy, that can be administered through a peripheral IV in a non-ICU setting.

Hyponatraemia during an emergency medical admission as a marker of illness severity & case complexity

BACKGROUND

Altered sodium balance at time of an emergency medical admission adversely impacts on outcome; whether hyponatraemia is independently associated with outcomes or a surrogate of acute illness severity has been debated.

METHODS

All emergency medical admissions between 2002 and 2017 were studied and a risk score calculated. We compared univarate deciles of admission sodium using a multivariable model, adjusting for risk score.

RESULTS

There were 106,586 admissions in 54,928 patients. Patients with lower sodium at admission were older at 66.7 years (IQR 46.7-79.5) compared with 63.3 years (IQR 42.9-78.2) with a longer length of stay (LOS) of 6.8 days (IQR 3.0-14.7) versus 4.9 days (IQR 1.8-10.9). They had a higher 30-day in-hospital mortality at 6.4% vs 4.4% (p < 0.001). Admission sodium predicted survival - OR 0.89 (95%CI 0.88-0.90). We adjusted the model with a Risk Score that is predictive and exponentially related to 30-day in-hospital mortality. When adjusted for Risk Score, the admission sodium value was less predictive - OR 0.95 (95%CI 0.92-0.97). The cumulative percentages within the lowest five deciles fell from 63.3% between 2002 and 2009 to 48.1% from 2010 to 2017. The slope of the prediction line relating admission sodium to mortality did not change over time but a lower mortality rate was predicted at any given sodium level.

CONCLUSION

Hyponatraemia at the time of an emergency medical admission is predictive and probably a marker of Acuity Illness Severity and Case Complexity. Both the frequency of abnormality in admission sodium and mortality have fallen over time.

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.

Case report: a thiazide diuretic to treat polyuria induced by tolvaptan

BACKGROUND

Currently, the vasopressin V2 receptor antagonist tolvaptan is the only available treatment for autosomal dominant polycystic kidney disease (ADPKD), but there are tolerability issues due to aquaretic side-effects such as polyuria. A possible strategy to ameliorate these side-effects may be addition of a thiazide diuretic, this is an established treatment in nephrogenic diabetes insipidus, a condition where vasopressin V2 receptor function is absent.

CASE PRESENTATION

We describe a 46-year-old male ADPKD-patient, who was prescribed tolvaptan, which caused polyuria of around 5 l per day. Hydrochlorothiazide was added to treat hypertension, which resulted in a marked decrease in urine production. While using tolvaptan, rate of eGFR decline was - 1.35 mL/min/1.73m2 per year, whereas after hydrochlorothiazide was initiated this was - 3.97 mL/minute/1.73m2 per year.

CONCLUSIONS

This case report indicates that while addition of hydrochlorothiazide may improve tolerability of vasopressin V2 receptor antagonists, co-prescription should only be used with great scrutiny as it may decrease tolvaptan effect on rate of ADPKD disease progression.

Sex differences in spontaneous reports on adverse drug events for common antihypertensive drugs

Purpose

To explore sex differences in spontaneously reported adverse drug events (ADEs) for antihypertensives in routine care.

Methods

A cross sectional analysis combining number of reports from the national pharmacovigilance database with data from the Swedish Prescribed Drug Register, from 2005 to 2012 for ACE inhibitors (ACE-I) and angiotensin receptor blockers (ARB), with or without thiazide, diuretics (thiazides, potassium-sparing agents, sulfonamides, aldosterone antagonists), selective betablockers, and dihydropyridine calcium-channel-blockers (DHPs). The total number of reports was adjusted to exposed patients and dispensed DDDs among women and men. Dose exposures, co-medications, and co-prescriptions were also analyzed.

Results

In women, a higher prevalence of ADE-reports was seen in ACE-I (odds ratio, OR 1.21; 95% CI 1.09–1.35), ACE-I-combinations (OR 1.61; 1.44–1.79), ARB-combinations (OR 2.12; 1.47–3.06), thiazides (OR 1.78; 1.33–2.39), diuretics and potassium-sparing agents (OR 1.62; 1.22–2.17), and DHPs (OR 1.40; 1.17–1.67), with a potential linkage to dose exposure. For aldosterone antagonists, we observed a higher prevalence of ADE reports in men (OR 0.75; 0.59–0.97) but without any sex difference in dose exposure.

Conclusions

This ecological study of reported ADEs showed a higher prevalence of reports in women in six out of ten groups of antihypertensive drugs, and this may potentially be linked to dose exposure. Aldosterone antagonists was the only group with a higher prevalence of ADE-reports in men with a similar dose exposure between women and men.

Electronic supplementary material

The online version of this article (10.1007/s00228-018-2480-y) contains supplementary material, which is available to authorized users.

Hyponatremia in the elderly: challenges and solutions

Decreased serum sodium concentration is a rather frequent electrolyte disorder in the elderly population because of the presence of factors contributing to increased antidiuretic hormone, the frequent prescription of drugs associated with hyponatremia and also because of other mechanisms such as the “tea and toast” syndrome. The aim of this review is to present certain challenges in the evaluation and treatment of hyponatremia in the elderly population and provide practical solutions. Hyponatremia in elderly subjects is mainly caused by drugs (more frequently thiazides and antidepressants), the syndrome of inappropriate antidiuretic hormone secretion (SIAD) or endocrinopathies; however, hyponatremia is multifactorial in a significant proportion of patients. Special attention is needed in the elderly population to exclude endocrinopathies as a cause of hyponatremia before establishing the diagnosis of SIAD, which then requires a stepped diagnostic approach to reveal its underlying cause. The treatment of hyponatremia depends on the type of hyponatremia. Special attention is also needed to correct serum sodium levels at the appropriate rate, especially in chronic hyponatremia, in order to avoid the osmotic demyelination syndrome. In conclusion, both the evaluation and the treatment of hyponatremia pose many challenges in the elderly population.

[Hyponatremia in emergency admissions - often dangerous]

Hyponatremia is the most common electrolyte disorder in clinical practice and associated with increased morbidity and mortality, independent of underlying disease. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema whilst over rapid correction of chronic hyponatremia can cause serious neurologic impairment and death resulting from osmotic demyelination. Still hyponatremia is often neglected and insufficiently addressed, most likely due to limited understanding of its pathophysiological mechanisms. Being familiar with only few basic principles of body fluid regulation may be a worthwhile investment into the clinical career and save patients' lives.

A retrospective case-control study evaluating thiazide-induced hyponatraemia-related hospitalisation among older Singaporeans

Introduction:

Thiazide diuretics are recommended as first-line therapy for hypertension in older adults. However, thiazides are also associated with hyponatraemia-related hospitalisations in older patients. This study aims to determine the predictors of hospitalisation due to thiazides usage in older adults.

Methods:

This is a retrospective matched case-control study. Patients aged ⩾65 admitted due to adverse drug reactions based on International Classification of Diseases, Ninth Revision (ICD9) codes from the period of 1 June to 31 December 2011 in Singapore General Hospital were extracted. Patients with the ICD9 code E944.3 Saluretics causing adverse effects in therapeutic use and who experienced thiazide-induced hyponatraemia were identified. Controls were identified from a pool of patients from outpatient clinics who were prescribed thiazide during the study period. Each case was matched to four controls based on gender and race. Patients’ demographics, length of stay, and cost of hospital admission were obtained.

Results:

In total, 19 cases with thiazide-induced hyponatraemia were matched with 76 controls. Cases were older than control (78.8±6.1 vs. 75.6±7.0, p=0.052), with the majority being females (84.2%) and Chinese (94.7%). The mean length of stay was 4 (±3) days; the mean cost of stay was SGD 1118 (±898). Serum potassium levels and concurrent use of beta-blockers were identified as unadjusted possible predictors for hospitalisation due to thiazide-induced hyponatraemia.

Conclusion:

Potential predictors of hospitalisation due to thiazide-induced hyponatraemia include low potassium levels and concurrent use of beta-blockers. Identification of predictors is crucial to guide safe and effective prescribing of thiazides in older patients.

Predictors of Long-Term Mortality in Patients With Acute Heart Failure

To investigate parameters which were related with long-term mortality in patients hospitalized for acute heart failure (AHF).A total of 287 patients with AHF presenting to the First Affiliated Hospital of Nanjing Medical University were enrolled into the registry from April 2012 to January 2015. The primary endpoint was all-cause mortality within 1 year; the association between variables and prognosis was assessed after 1 year.Among the 287 patients, 17 did not continue follow-up and 47 (17.4%) passed away. Baseline NT-proBNP and sST2 concentrations were higher amongst deceased than among survivors (P < 0.001). Serum sodium concentrations of patients who died were lower (P < 0.001). In receiver operator characteristics (ROC) analyses, the area under the curve (AUC) values for NT-proBNP, sST2, and serum sodium to predict 1-year mortality were 0.699 (95%CI 0.639-0.755), 0.692, (95%CI 0.634-0.747), and 0.694 (95%CI 0.634-0.750), respectively. The optimal cut-off points for NT-proBNP, sST2, and serum sodium were 2137.0 ng/L, 35.711 ng/mL, and 136.6 mmol/L, respectively. In Cox regression analysis, ln-transformed NT-proBNP (HR 1.546, P = 0.039), ln-transformed sST2 (HR1.542, P = 0.049), and serum sodium (HR 0.880, P = 0.000) values reliably predicted long-term mortality after multivariable adjustment.In patients with acute heart failure, NT-proBNP, sST2 and serum sodium are potential predictors of 1-year mortality.

Hypothyroidism and Hyponatremia: Rather Coincidence Than Causality

BACKGROUND

Hypothyroidism is referred to be a rare but possible cause of hyponatremia. However, there is only poor evidence supporting this association. Since hyponatremia and hypothyroidism are both common conditions themselves, co-occurrence does not have to be causal.

METHODS

To address a potential relationship, a retrospective analysis of data from the Division of Endocrinology of the Medical University of Vienna from April 2004 to February 2016 was performed. A total of 8053 hypothyroid patients (48 ± 18 years of age; 71% female) with thyrotropin >4.0 μIU/mL and available blood tests for free thyroxine and sodium (Na⁺) within maximal ± seven days were included and screened for hyponatremia. Patients' records were searched for concomitant disease and medication when Na⁺ concentration was <135 mmol/L.

RESULTS

Hyponatremia was present in 448/8053 (5.56%) patients. Analysis of medical history revealed potential alternative causes of hyponatremia in 442/448 (98.88%) patients (i.e., side effects of medication, concomitant underlying disease, or other endocrine disorders). This distribution did not differ between patients suffering from clinical or subclinical hypothyroidism. No case of clinically relevant hyponatremia (Na⁺ < 130 mmol/L), present in 111/448 (24.78%) patients could be attributed only to hypothyroidism. There was a very weak but statistically significant trend toward a positive association between thyroid function and serum Na⁺ levels (Na⁺/thyrotropin: R = 0.022, p = 0.046; Na⁺/free thyroxine: R = -0.047, p < 0.001).

CONCLUSION

The results suggest that hypothyroid patients with moderate to severe hyponatremia often have other potential explanations for their low serum Na⁺ concentrations in routine care.

Thiazide-Associated Hyponatremia, Report of the Hyponatremia Registry: An Observational Multicenter International Study

BACKGROUND

Hyponatremia is a frequent and potentially life-threatening adverse side effect of thiazide diuretics. This sub-analysis of the Hyponatremia Registry database focuses on current management practices of thiazide-associated hyponatremia (TAH) and compares differences between TAH and syndrome of inappropriate antidiuretic hormone secretion (SIADH).

METHODS

We analyzed 477 patients from 225 US and EU sites with euvolemic hyponatremia ([Na+] ≤130 mEq/L) who were receiving a thiazide diuretic. Of these, 118 met criteria for true thiazide-induced hyponatremia (TIH).

RESULTS

Thiazide was withdrawn immediately after hyponatremia was diagnosed only in 57% of TAH; in these patients, the median rate of [Na+] change (Δdaily[Na+]) was significantly higher than those with continued thiazide treatment (3.8 [interquartile range: 4.0] vs. 1.7 [3.8] mEq/L/day). The most frequently employed therapies were isotonic saline (29.6%), fluid restriction (19.9%), the combination of these two (8.2%), and hypertonic saline (5.2%). Hypertonic saline produced the greatest Δdaily[Na+] (8.0[6.4] mEq/L/day) followed by a combination of fluid restriction and normal saline (4.5 [3.8] mEq/L/day) and normal saline alone (3.6 [3.5] mEq/L/day). Fluid restriction was markedly less effective (2.7 [2.7] mEq/L/day). Overly rapid correction of hyponatremia occurred in 3.1% overall, but in up to 21.4% given hypertonic saline. Although there are highly significant differences in the biochemical profiles between TIH and SIADH, no predictive diagnostic test could be derived.

CONCLUSIONS

Despite its high incidence and potential risks, the management of TAH is often poor. Immediate withdrawal of the thiazide is crucial for treatment success. Hypertonic saline is most effective in correcting hyponatremia but associated with a high rate of overly rapid correction. We could not establish a diagnostic laboratory-based test to differentiate TIH from SIADH.

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.

Hydrochlorothiazide in intensive care unit-acquired hypernatremia: A randomized controlled trial

PURPOSE

Thiazides are suggested as a treatment for intensive care unit (ICU)-acquired hypernatremia (IAH). The primary aim of the study was reducing serum sodium concentration (sNa) in patients with IAH with hydrochlorothiazide (HCT) in comparison to placebo. Secondary end points were a difference in urine sodium concentration (uNa) and duration of severe IAH.

MATERIALS

A monocentric, double-blind, placebo-controlled trial was conducted in 50 patients with IAH and urine potassium + uNa less than sNa in a spot urine sample. Patients were randomized to HCT 25 mg or placebo 1 qd for maximal 7 days. Patients on renal replacement therapy, on medication inducing diabetes insipidus, or with recent use of diuretics were excluded. IAH was defined as sNa of at least 143 mmol/L.

RESULTS

At baseline, sNa and uNa were comparable between groups. During the study period, sNa decreased significantly with median 4 mmol/L in both groups, with no significant difference between groups (P=.32). Median uNa increased significantly in both groups (46 [16-86] mmol/L in the HCT-group; 20 [10-66]mmol/L in the placebo group), with no difference between groups (P=.34). Median duration of sNa of at least 145 mmol/L was 3 days in both groups (P=.91).

CONCLUSION

HCT 25 mg 1 qd did not significantly affect sNa or uNa in patients with IAH.

The Hyponatremia Epidemic: A Frontier Too Far?

Hyponatremia is the most common electrolyte abnormality and is often neglected, especially in elderly and seemingly terminal patients. Hyponatremia can be asymptomatic or can cause symptoms ranging from nausea and lethargy to convulsions and coma. This condition has become increasingly common over time with a similar time course to the increase in adoption of low salt diets. The popularization of low salt may not be justified in people with normal kidney function in whom the compatible statistically based evidence that salt causes hypertension has been challenged by experimental evidence to the contrary.

Loop Diuretics in the Treatment of Hypertension

Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

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.

Hyponatremia in patients hospitalized with heart failure: a condition often overlooked in low-income settings

Background

Hyponatremia is a common electrolyte abnormality in patients with heart failure (HF). It is independently associated with increased short-term and long-term morbidity and mortality. The main objective of this study was to assess patterns of hyponatremia and its association with discharge outcomes in patients with HF admitted to a teaching hospital in Ethiopia.

Patients and methods

This is a descriptive, prospective, hospital-based cohort study of patients with HF admitted to Jimma University Hospital, Ethiopia, between November 1, 2013 and July 31, 2014. A structured questionnaire was used to collect information on sociodemographic characteristics, clinical profile at admission, and outcomes at discharge. Plasma sodium concentration was analyzed at admission for all patients. The relationship between hyponatremia at admission and in-hospital mortality, as well as length of hospital stay, was assessed using both bivariate analysis and multivariable logistic regressions. The level of statistical significance was set at P<0.05.

Results

Of 152 participants admitted with HF, 44 (28.9%) had hyponatremia, which is defined as serum sodium level <135 mmol/L. Patients on salt restriction, on chronic diuretic treatment (furosemide and spironolactone), and with impaired renal function at admission were found to be highly affected. Hyponatremia was found to be associated with increased in-hospital mortality (P=0.008) and longer hospital stay (16.6 vs 12 days, P<0.001). Patients with hyponatremia also had lower blood pressure and poor functional status at discharge.

Conclusion

This study demonstrates that hyponatremia is highly prevalent in patients hospitalized with HF and is associated with increased in-hospital mortality and longer hospital stay. Thus, great emphasis should be given to identify high-risk patients, and prevention and early detection of hyponatremia to prevent its deleterious effects. Large-scale national studies are also needed to complement our findings.

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.

Hourly oral sodium chloride for the rapid and predictable treatment of hyponatremia

Hypertonic NaCl is first-line therapy for acute, severe and symptomatic hyponatremia; however, its use is often restricted to the intensive care unit (ICU). A 35-year-old female inpatient with an optic chiasm glioma and ventriculoperitoneal shunt for hydrocephalus developed acute hyponatremia (sodium 122 mEq/l) perhaps coinciding with haloperidol treatment. The sum of her urinary sodium and potassium concentrations was markedly hypertonic vis-à-vis plasma; it was inferred that serum sodium concentration would continue to fall even in the complete absence of fluid intake. Intravenous (i.v.) 3% NaCl was recommended; however, a city-wide public health emergency precluded her transfer to the ICU. She was treated with hourly oral NaCl tablets in a dose calculated to deliver the equivalent of 0.5 ml/kg/h of 3% NaCl with an objective of increasing the serum sodium concentration by 6 mEq/l. She experienced a graded and predictable increase in serum sodium concentration. A slight overshoot to 129 mEq/l was rapidly corrected with 0.25 l of D5W, and she stabilized at 127 mEq/l. We conclude that hourly oral NaCl, in conjunction with careful monitoring of the serum sodium concentration, may provide an attractive alternative to i.v. 3% NaCl for selected patients with severe hyponatremia.

A cross-sectional study of hyponatraemia among elderly patients with heart failure in Uganda

BACKGROUND

Hyponatraemia is a common electrolyte disturbance among older patients. We determined the prevalence of and factors associated with hyponatraemia among older patients with predominantly acute decompensated heart failure attending a tertiary hospital in Kampala, Uganda.

OBJECTIVES

Main study aim: (1) to determine the prevalence of hyponatraemia among patients aged 60 years and above with heart failure attending Mulago National Referral Hospital; (2) to describe the factors associated with hyponatraemia among patients aged 60 years and above with heart failure attending Mulago National Referral Hospital.

SETTING

The study was conducted in one tertiary hospital located in the northeast of Kampala, Uganda.

PARTICIPANTS

400 adults aged 60 years and above were identified for the study. Of these, 188 were excluded as they did not fulfil the inclusion criteria and one declined to participate, leaving a final study group of 211 older adults aged 60 years and above, with a clinical diagnosis of heart failure using Framingham's criteria.

RESULTS

The prevalence of hyponatraemia was 24.2% (51/211). Hyponatraemia was mainly found in patients with mild-to-moderate heart failure, New York Heart Association classes 2 and 3. Of the 51 patients with hyponatraemia, 27 (52.9%) had mild hyponatraemia, while 24 (47.1%) had moderate to severe hyponatraemia of 130-125 mmol/L. History of vomiting (OR=2.94, 95% CI 1.29 to 6.70, p=0.010) and use of loop diuretics (OR=2.71, 95% CI 1.13 to 6.52, p=0.026) were identified as independent factors associated with hyponatraemia among older patients with heart failure.

CONCLUSIONS

Our study revealed a relatively high prevalence of hyponatraemia among older patients with mild to moderate heart failure. Patients presenting with a history of vomiting from any cause or use of loop diuretics were more likely to have hyponatraemia.

Thiazide-associated hyponatremia in the elderly: what the clinician needs to know

Thiazide-induced hyponatremia is one of the main causes of decreased sodium levels in elderly individuals. This review presents the current evidence regarding the thiazide-associated hyponatremia. Thiazide-associated hyponatremia is observed mainly in patients with certain risk factors such as those receiving large doses of thiazides, having much comorbidity, such as heart failure, liver disease or malignancy, and taking several medications, such as non-steroidal anti-inflammatory drugs, selective serotonin re-uptake inhibitors or tricyclic antidepressants. Sodium concentration should be monitored in patients with risk factors for developing thiazide-associated hyponatremia and clinicians should measure promptly serum sodium levels in patients with neurologic signs indicating reduced sodium levels. The clinical and biochemical profile of patients with thiazide-associated hyponatremia may be that of extracellular volume depletion or the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The investigation of possible thiazide-associated hyponatremia includes the exclusion of other causes of decreased sodium levels and the identification of the characteristics of hyponatremia due to thiazides (extracellular volume depletion-related or SIADH-like). Treatment should be carefully monitored to avoid serious neurologic complications due to overcorrection. Clinicians should discourage prescribing thiazides in patients with a history of diuretic-associated hyponatremia and should prefer low doses of thiazides in patients with risk factors for developing thiazide-associated hyponatremia.

Thiazide-induced hyponatraemia is associated with increased water intake and impaired urea-mediated water excretion at low plasma antidiuretic hormone and urine aquaporin-2

BACKGROUND

Hyponatraemia is a common, potentially life-threatening, complication of thiazide diuretics. The mechanism of thiazide-induced hyponatraemia is incompletely understood. Previous experiments have suggested a direct effect of thiazide diuretics on the plasma membrane expression of aquaporin (AQP)2.

METHODS

We examined the effects of a single re-exposure to hydrochlorothiazide (HCTZ) 50 mg on water balance, renal sodium handling and osmoregulation in 15 elderly hypertensive patients with a history of thiazide-induced hyponatraemia and 15 matched hypertensive controls using thiazide diuretics without previous hyponatraemia.

RESULTS

Patients with thiazide-induced hyponatraemia had significantly lower body weight and lower plasma sodium and osmolality at baseline. After HCTZ administration, plasma sodium and osmolality significantly decreased and remained lower in patients compared with controls (P < 0.001). Plasma antidiuretic hormone (ADH) and urine AQP2 were low or suppressed in patients, whereas solute and electrolyte-free water clearance was significantly increased compared with controls. Ad libitum water intake was significantly higher in patients (2543 ± 925 ml) than in controls (1828 ± 624 ml, P < 0.05), whereas urinary sodium excretion did not differ. In contrast, urea excretion remained significantly lower in patients (263 ± 69 mmol per 24 h) compared with controls (333 ± 97 mmol per 24 h, P < 0.05) and predicted the decrease in plasma sodium following HCTZ administration.

CONCLUSION

Thiazide diuretics are associated with markedly impaired free water excretion at low ADH and AQP2 in elderly patients. The higher water intake and lower urea excretion in patients points to an important role for polydipsia and urea-mediated water excretion in the pathogenesis of thiazide-induced hyponatraemia.

Mild Chronic Hyponatremia in the Ambulatory Setting: Significance and Management

Mild chronic hyponatremia, as defined by a persistent (>72 hours) plasma sodium concentration between 125 and 135 mEq/L without apparent symptoms, is common in ambulatory patients and generally perceived as being inconsequential. The association between increased mortality and hyponatremia in hospitalized patients in various settings and etiologies is widely recognized. This review analyzes the significance of mild chronic hyponatremia in ambulatory subjects and its effects on mortality and morbidity. It addresses whether this disorder should even be treated and if so, which patients are likely to benefit from treatment. The available approaches to correct hyponatremia in such patients in the context of recently published panel-generated recommendations and guidelines are described.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Hyponatremia in the outpatient setting: clinical characteristics, risk factors, and outcome

PURPOSE

Hyponatremia is a common disorder and hyponatremia in the outpatient setting is not extensively studied. Our aim was to investigate the characteristics of hyponatremia in ambulatory patients.

METHODS

Seventy-six adult outpatients with hyponatremia were enrolled in this prospective study. Demographic features, presenting symptoms and signs, associating morbidities, medications, laboratory findings, mortalities, and length of hospital stay, were recorded.

RESULTS

Mean age was 74.7 ± 12.7 years, and 52 (68.4 %) were female whereas 24 (31.6 %) were male. Mean sodium concentration was 123.6 ± 6.6 mEq/L. Leading cause was thiazide diuretic use (n = 37, 48.7 %) and approximately half of the patients (n = 40, 52.6 %) had a multifactorial etiology. Severe hyponatremia (sodium < 125 mEq/L) was identified in 37 (48.7 %). Thiazide diuretic use, vomiting, and apathy were independent predictors of severe hyponatremia. Eight (10.5 %) patients had a mortal course. A relatively younger age, male gender, presenting sign of lethargy, associating morbidities of malignancy, chronic liver disease, and hypoalbuminemia were risk factors for mortality.

CONCLUSIONS

Hyponatremia is prevalent among elderly, especially in women and with thiazide diuretics. Apart from the trend toward sodium depletion observed in healthy elderly which occurs due to changes in the tubular handling of sodium, a multifactorial etiology including thiazides seems to predict the occurrence and the severity of hyponatremia. Hyponatremia may be a significant cause of mortality in seniors. A relatively younger age, male gender, association of cirrhosis, malignancy, and hypoalbuminemia predict mortality. In elderly outpatients, identification of the risk factors for hyponatremia and close monitoring are imperative to reduce the related mortality and morbidity.

Clinical and Genetic Factors Associated With Thiazide-Induced Hyponatremia

Thiazide diuretics are associated with an increased risk of hyponatremia. The aim of this study was to investigate possible predictors of thiazide-induced hyponatremia.A total of 48 patients admitted to the ward or to the emergency department due to severe thiazide-induced hyponatremia (Na < 125 mmol/L) were enrolled in our study as the case group. Another 211 hypertensive patients with normal sodium levels after treatment with thiazide diuretics were selected as the control group. Twelve tag single nucleotide polymorphism markers were selected from the Potassium Channel, Inwardly Rectifying Subfamily J, Member 1 (KCNJ1) gene: rs1231254, rs2238009, rs1148058, rs675482, rs673614, rs12795437, rs2855800, rs2509585, rs3016774, rs881333, rs4529890, and rs7116606. Clinical and genetic parameters between patients with thiazide-induced hyponatremia and the control group were compared. Logistic regression was used to analyze data.The patients with thiazide-induced hyponatremia were older (P < 0.001), predominantly female (P = 0.008), had a lower mean body mass index (BMI) (P < 0.001), and more commonly used angiotensin II receptor antagonist (P < 0.001) and spironolactone (P = 0.007) compared with the control groups. Analysis with multivariate logistic regression revealed that age (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.08-1.19, P < 0.001), female gender (OR, 4.49; 95% CI, 1.54-13.11, P = 0.006), BMI (OR, 0.80; 95% CI, 0.69-0.93, P = 0.003), and KCNJ1 rs2509585 C/T or T/T polymorphisms (OR, 5.75; 95% CI, 1.25-26.45, P = 0.03) were independent predictors for thiazide-induced hyponatremia.Older female patients with lower BMIs and KCNJ1 rs2509585 C/T or T/T polymorphisms were more likely to develop thiazide-induced hyponatremia.

[Hyponatremias: From pathophysiology to treatments. Review for clinicians]

Hyponatremia could be defined as a public health topic: too many patients are concerned in both hospitalized and general populations; hyponatremia induces lots of clinical outcomes and a great economic burden. Its pathophysiology involves thirst regulation (hypotonic water intakes) and losses regulation (through the kidney under vasopressin control). Diagnostic approach should insure that hyponatremia reflects hypo-osmolality and hypotonicity: first, a false hyponatremia should be ruled out, then a non-hypotonic one. Next step is clinic: extracellular status should be evaluated. When increased, any edematous status should be evoked: heart failure, liver cirrhosis or nephrotic syndrome. When decreased, any cause of extracellular dehydration should be evoked: natriuresis could help distinguishing between renal (adrenal insufficiency, diuretics use or salt-losing nephropathy) or extrarenal (digestive mostly) etiologies. When clinically normal, a secretion of inappropriate antidiuretic hormone (SIADH) should be evoked, once hypothyroidism or hypoadrenocorticism have been ruled out. Therapy depends on the severity of the clinical impact. From extracellular rehydration, through fluid restriction, the paraneoplastic and heart failure-induced SIADH benefit from a new class of drug, available among the therapeutic strategies: aquaretics act through antidiuretic hormone receptor antagonism (vaptans). Their long-term benefits still have to be proven but it is a significant step forward in the treatment of hyponatremias.

Management of severe hyponatremia: infusion of hypertonic saline and desmopressin or infusion of vasopressin inhibitors?

Rapid correction of severe hyponatremia carries the risk of osmotic demyelination. Two recently introduced methods of correction of hyponatremia have diametrically opposite effects on aquaresis. Inhibitors of vasopressin V2 receptor (vaptans) lead to the production of dilute urine, whereas infusion of desmopressin causes urinary concentration. Identification of the category of hyponatremia that will benefit from one or the other treatment is critical. In general, vaptans are effective in hyponatremias presenting with concentrated urine and, with the exception of hypovolemic hyponatremia, can be used as their primary treatment. Desmopressin is effective in hyponatremias presenting with dilute urine or developing urinary dilution after saline infusion. In this setting, desmopressin infusion helps prevent overcorrection of the hyponatremia. Monitoring of the changes in serum sodium concentration as a guide to treatment changes is imperative regardless of the initial treatment of severe hyponatremia.

Severe hyponatremia associated with thiazide diuretic use

BACKGROUND

Thiazide diuretics are commonly used as first-line antihypertensive agents. Hyponatremia is a reported, though uncommon, complication of thiazide use. Although the exact mechanism of thiazide-induced hyponatremia (TIH) is unclear, it can be a significant cause of morbidity and mortality.

CASE REPORT

We report a 69-year-old man with generalized weakness beginning 2 weeks after starting hydrochlorothiazide (HCTZ). Evaluation revealed a serum sodium level of 120 mmol/L. The patient was admitted and successfully treated with free water restriction and discontinuation of the HCTZ. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Hyponatremia is an uncommon complication of thiazide diuretic use, which frequently presents with nonspecific symptoms. Identification of TIH is crucial to prevent its potentially life-threatening complications.

Risk of thiazide-induced metabolic adverse events in older adults

OBJECTIVES

To evaluate the risk and predictors of thiazide-induced adverse events (AEs) in multimorbid older adults in real-world clinical settings.

DESIGN

Observational cohort study.

SETTING

National Veterans Affairs data from 2007 to 2008.

PARTICIPANTS

Veterans aged 65 and older newly prescribed a thiazide (N = 1,060) compared with propensity-matched nonusers of antihypertensive medications (N = 1,060).

MEASUREMENTS

The primary outcome was a composite of metabolic AEs defined as sodium less than 135 mEq/L, potassium less than 3.5 mEq/L, or a decrease in the estimated glomerular filtration rate (eGFR) of more than 25% from the baseline rate. Secondary outcomes included sev-ere AEs (sodium <130 mEq/L, potassium <3.0 mEq/L, or a decrease in eGFR of more than 50%).

RESULTS

Over 9 months of follow-up, 14.3% of new thiazide users developed an AE, compared with 6.0% of nonusers (number needed to harm (NNH) 12, 95% confidence interval (CI) = 9-17, P < .001); 1.8% of new users developed a severe AE, compared with 0.6% of nonusers (NNH = 82, P = .008), and 3.8% of new users had an emergency department visit or hospitalization with an AE, compared with 2.0% of nonusers (NNH = 56, P = .02). Risk of AEs did not vary according to age, but having five or more comorbidities was associated with 3.0 times the odds (95% CI = 1.4-6.2) of developing an AE as having one comorbidity (hypertension). Low-normal and unmeasured baseline sodium and potassium values were among the strongest predictors of hyponatremia and hypokalemia, respectively. Only 42% of thiazide users had laboratory monitoring within 90 days after initiation.

CONCLUSION

Thiazide-induced AEs are common in older adults. Greater attention should be paid to potential complications in prescribing thiazides to older adults, including closer laboratory monitoring before and after initiation of thiazides.