Hyponatremia and bone: an emerging relationship

Association of Pre-Operative Hyponatraemia with Morbidity and Mortality in Patients Undergoing Non-Urgent Degenerative Spine Surgery, a Retrospective Study

BACKGROUND AND OBJECTIVES

Hyponatraemia increases the morbidity and mortality risks of orthopaedic patients. When undergoing spine surgery, hyponatraemic patients have high risks of pneumonia and of staying in hospital for up to 1 day longer compared with non-hyponatraemic patients. This study aims to assess the occurrence of adverse events among patients with pre-operative hyponatraemia after undergoing lumbar surgery.

MATERIALS AND METHODS

A retrospective cohort study was conducted. Patients who underwent spinal surgery in 2011 to 2013 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. Multivariate analysis was conducted to demonstrate the difference in post-operative complication rates between hyponatraemic patients and normonatraemic patients. Post-operative adverse events, need for blood transfusion and length of stay were considered as clinical outcome data.

RESULTS

A total of 58,049 patients were included; pre-operatively, 55,012 (94.8%) were normonatraemic and 3037 (5.2%) were hyponatraemic. Multivariate analysis showed that hyponatraemic patients had higher rates of adverse events, blood transfusions and urinary tract infections. Specifically, 632 (20.8%) hyponatraemic patients developed adverse events, compared with 6821 (12.4%) normonatraemic patients; the hyponatraemic patients received transfusions, compared with 6821 (7.4%) normonatraemic patients; and 97 (3.2%) hyponatraemic patients developed urinary tract infections, compared with 715 (1.3%) normonatraemic patients. Finally, an extended length of stay beyond 6 days occurred in 604 (19.9%) hyponatraemic patients, compared with 4676 (8.5%) normonatraemic patients.

CONCLUSIONS

Our study identified an association between pre-operative hyponatraemia and post-operative adverse events in spinal surgery patients. However, it is unclear whether hyponatraemia caused the higher adverse event rate.

The Influence of Hyponatremia and Hypokalemia on the Risk of Fractures in Various Anatomical Regions among Adult Trauma Patients: A Propensity Score-Matched Analysis

BACKGROUND

Hyponatremia and hypokalemia are common electrolyte imbalances in trauma patients and have been identified to be risk factors for a fall. In addition, hyponatremia was reported to be related to osteoporosis and fragility fractures, while the association between hypokalemia and osteoporosis has only been reported in rare case reports. This study investigated the impact of hyponatremia and hypokalemia on the incidence of fractures in various body regions of adult trauma patients, using the propensity score-matched patient cohort to reduce the influence of patients' baseline characteristics.

METHODS

The study analyzed data from 11,173 hospitalized adult trauma patients treated from 1 January 1998, to 31 December 2022. The study included 1968 patients with hyponatremia and 9205 without, and 1986 with hypokalemia and 9187 without. Different 1:1 propensity score-matched cohorts were generated to create the 1903 pairings of patients with or without hyponatremia, 1977 pairings of patients with or without hypokalemia, and 380 pairing of patients with both hyponatremia and hypokalemia vs. normal control patients. Analysis was conducted on the incidence of fracture in various anatomic regions.

RESULTS

Hyponatremic patients had increased odds of thoracic vertebral fracture [odds ratio (95% confidence interval) 1.63 (1.10-2.42), p = 0.014], pelvic fracture [2.29 (1.12-4.67), p = 0.019], and femoral fracture [1.28 (1.13-1.45), p < 0.001] but decreased odds of radial and patella fractures. Hypokalemic patients showed no significant differences in fracture risk except for a decreased likelihood of radial fractures. The patients with both hyponatremia and hypokalemia showed a decreased likelihood of radial fractures and patella fractures.

CONCLUSION

Hyponatremia may have a greater impact on the occurrence of bone fractures than hypokalemia in trauma patients who have suffered a fall. Electrolyte abnormalities should be taken into account while assessing the risk of fractures in trauma patients.

Association of hyponatremia with bone mineral density and fractures: a narrative review

Recent studies suggest a possible association of hyponatremia with osteoporosis, falls and bone fractures. The objectives of this narrative review were to further explore this association and the related pathophysiological mechanisms and to suggest a practical approach to patients with osteoporosis or chronic hyponatremia in clinical practice. We conducted an extensive PubMed search until October 2022 with the combination of the following keywords: 'hyponatremia' or 'sodium' or 'SIADH' and 'fractures' or 'bone' or 'osteoporosis', as MeSH Terms. Review of numerous observational studies confirms a significant independent association of, even mild, hyponatremia with two- to three-fold increase in the occurrence of bone fractures. Hyponatremia is a risk factor for osteoporosis with a predilection to affect the hip, while the magnitude of association depends on the severity and chronicity of hyponatremia. Chronic hyponatremia also increases the risk for falls by inducing gait instability and neurocognitive deficits. Besides the detrimental impact of hyponatremia on bone mineral density and risk of falls, it also induces changes in bone quality. Emerging evidence suggests that acute hyponatremia shifts bone turnover dynamics towards less bone formation, while hyponatremia correction increases bone formation. The key unanswered question whether treatment of hyponatremia could improve osteoporosis and lower fracture risk highlights the need for prospective studies, evaluating the impact of sodium normalization on bone metabolism and occurrence of fractures. Recommendations for clinical approach should include measurement of serum sodium in all individuals with fracture or osteoporosis. Also, hyponatremia, as an independent risk factor for fracture, should be taken into consideration when estimating the likelihood for future fragility fracture and in clinical decision-making about pharmacological therapy of osteoporosis. Until it is proven that normalization of sodium can lower fracture occurrence, correcting hyponatremia cannot be universally recommended on this basis, but should be decided on a case-by-case basis.

A tool for safer prescribing in vulnerable adults: the continuing development of the Medichec app and website

AIMS AND METHOD

Adverse effects are a common concern when prescribing and reviewing medication, particularly in vulnerable adults such as older people and those with intellectual disability. This paper describes the development of an app giving information on side-effects, called Medichec, and provides a description of the processes involved in its development and how drugs were rated for each side-effect. Medications with central anticholinergic action, dizziness, drowsiness, hyponatraemia, QTc prolongation, bleeding and constipation were identified using the British National Formulary (BNF) and frequency of occurrence of these effects was determined using the BNF, product information and electronic searches, including PubMed.

RESULTS

Medications were rated using a traffic light system according to how commonly the adverse effect was known to occur or the severity of the effect.

CLINICAL IMPLICATIONS

Medichec can facilitate access to side-effects information for multiple medications, aid clinical decision-making, optimise treatment and improve patient safety in vulnerable adults.

Hormones and Aging: An Endocrine Society Scientific Statement

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

A Survey Study on the Status of Somatic Symptoms in Young and Middle-Aged Patients with Mental Illness during Long-Term Hospitalization

Psychiatric disorders include severe psychiatric disorders and those in general with some psychiatric disorders having a clear etiology or in which a significant psychiatric predisposing factor is present. Whereas, psychiatric disorders precisely refer to those characterized by mild depression and mild anxiety and appear to affect a large number of people in any community. It has been reported that the disease is highly prevalent and has a huge impact on the individual, family, and community levels, resulting in a heavy burden on the healthcare system of a country. To explore the status of somatic symptoms in young and middle-aged psychiatric patients during long-term hospitalization, a total of 114 young and middle-aged psychiatric patients with prolonged hospitalization (more than 5 years) were included. Data information of the hospitalized patients was recorded, including preadmission somatic symptoms, electrocardiogram (ECG), echocardiogram, abdominal ultrasound, and blood tests. In addition, a homemade questionnaire was administered, and general information about the patients was also collected, including gender, age, current medication use, and duration of medication use. Correlations between cardiometabolic disease, osteoporosis, and long-term oral antipsychotic medication were analyzed in these young and middle-aged patients. The prevalence of comorbid somatic symptoms was 77.2%, and concomitant disorders included mainly cardiometabolic disorders, osteoporosis, pulmonary infections, cerebrovascular disorders, digestive disorders, fractures, and skin conditions. The incidence of somatic symptoms caused by long-term use of antipsychotic drugs was about 88.6%, and the incidence of concomitant somatic symptoms was higher in young and middle-aged psychiatric patients who were hospitalized for a long time. The current study observed a high prevalence of somatic symptoms in young and middle-aged patients with long-term inpatient psychiatric illness. Endocrine and metabolic disorders, particularly dyslipidemia, may trigger a range of deleterious effects. In addition to this, there is a high incidence of osteoporosis. Special attention should be paid to the side effects of antipsychotic drugs, and appropriate measures are needed to make early diagnosis and provide early treatment to reduce the occurrence of cardiometabolic diseases and osteoporosis.

The association between normal serum sodium levels and bone turnover in patients with type 2 diabetes

BACKGROUND

Sodium is a critically important component of bones, and hyponatremia has firmly been established as a risk factor associated with the incidence of fragility fractures. However, researches have also revealed that lower serum sodium are linked to reductions in muscle mass and a higher risk of cardiovascular disease even when these levels are within the normal range. Accordingly, this study was developed to examine the relationships between normal serum sodium concentrations and bone turnover in patients with type 2 diabetes (T2D).

METHODS

Patients with T2D were enrolled in the present study from January 2021 to April 2022. All patients underwent analyses of serum sodium levels, oral glucose tolerance testing (OGTT), bone turnover markers (BTMs), and dual-energy X-ray absorptiometry (DXA) scanning. BTMs included bone formation markers osteocalcin (OC) and N-terminal propeptide of type-I procollagen (PINP), and bone resorption marker C-terminal telopeptide (CTx). Patients were stratified into three subgroups based on the tertiles of their serum sodium concentrations.

RESULTS

In total, 372 patients with T2D and sodium levels in the normal range were enrolled in this study. Serum OC and PINP levels were increased from subgroup with the low sodium tertile to that with the high sodium tertile (p for trend < 0.05), whereas CTx level was comparable among the subgroups. A positive correlation was detected between serum sodium levels and both lnOC (r = 0.210, p < 0.001) and lnPINP (r = 0.196, p < 0.001), with these relationships remaining significant even following adjustment for age, sex, body mass index (BMI), and HbA1c. Only after adjusting for these four factors a positive correlation was detected between serum sodium levels and CTx levels (r = 0.108, p < 0.05). Linear regression analyses revealed that following adjustment for potential covariates, serum sodium level was and positively significantly associated with lnOC level (β = 0.134, t = 2.281, p < 0.05) and PINP level (β = 0.179, t = 3.023, p < 0.01).

CONCLUSION

These results highlight a significant association between low-normal serum sodium levels and low bone turnover.

Elderly with refractory chronic severe hyponatremia and anesthesia management dilemma: a case report with literature review

Hyponatremia is a common electrolyte disorder, especially in the frail elderly population. With the increasing number of surgeries in the aging population, hyponatremia is frequently encountered by anesthesiologists and surgeons. Unfortunately, management of hyponatremia is often complex in the elderly population as it is often multifactorial, and they are physiologically susceptible. While it is well known that preoperative hyponatremia is associated with increased perioperative morbidity and mortality, a lack of recommendations or guidelines adds to the dilemma in managing such cases. The most common cause of chronic hyponatremia in the elderly is the syndrome of inappropriate antidiuretic hormone (SIADH), which can be resistant to conventional treatment. On the other hand, paraneoplastic SIADH leading to hyponatremia is rare, and surgery may be the only option available for its correction. We present a case of a 78- years-gentleman to highlight such a dilemma. He was diagnosed with renal cell carcinoma and had chronic refractory severe hyponatremia despite treatment with fluid restriction, low dose hydrocortisone, tolvaptan, and 3% sodium chloride.

Do the etiology of hyponatremia and serum sodium levels affect the length of hospital stay in geriatric patients with hyponatremia?

Background

Hyponatremia can lead to a prolonged hospital stay and increased morbidity and mortality rates in geriatric patients. This study aimed to evaluate the effects of hyponatremia etiology and serum sodium (Na) levels on hospitalisation time in geriatric patients hospitalised due to hyponatremia.

Methods

The demographic characteristics, laboratory data, etiology of hyponatremia, and length of hospital stay were retrospectively recorded for 132 patients over 65 years of age who were hospitalised for hyponatremia.

Results

Of the 132 patients, 90 were female (68.2%), and 42 were male (31.8%). The serum Na levels of 66 (50%) patients were <120 mmol/L, those of 64 (48.5%) patients were 120-129 mmol/L, and those of two (1.5%) patients were >130 mmol/L. One hundred nine (82.6%) patients had hypoosmolar hyponatremia, 14 (10.6%) patients had isoosmolar hyponatremia, and nine (6.8%) patients had hyperosmolar hyponatremia. Also, 19.7% of the patients were hypovolemic, 37.9% were euvolemic, and 42.4% were hypervolemic. Hyponatremia etiology was congestive heart failure in 38 (28.8%) patients, syndrome of inappropriate antidiuretic hormone in 29 (22.0%) patients, gastrointestinal fluid loss in 24 (18.2%) patients, renal pathologies in 20 (15.2%) patients, the presence of drugs in 20 (15.2%) patients, and hypocortisolemia in one (0.8%) patient. The mean length of hospital stay for the patients was five (1-60) days. There was no statistically significant difference between the lengths of hospital stay based on hyponatremia etiology and serum Na levels (p=0.861 and p=0.076). It was observed that the lengths of stay for patients who developed hyponatremia during their hospitalisation in various clinics were longer than those for patients who presented to the emergency department (p<0.001).

Conclusions

In this study, it was determined that the length of hospital stay did not change with the etiology of hyponatremia and serum Na level at the time of admission, but patients who developed hyponatremia during their hospitalisation had longer hospitalisation times.

Hyponatremia, Hypokalemia, and Fragility Fractures in Old Patients: More than an Association?

PURPOSE

Hyponatremia and hypokalemia are common among elderly and have been associated with osteoporosis, we evaluate the role of these electrolytes as risk for fragility fractures.

METHODS

This study is divided in two parts: one retrospective and one prospective. We retrospectively collected data on urgently admitted patients for femoral fragility fractures (Fx) or for acute myocardial infarction (AMI), and patients admitted for elective hip/knee replacement surgery for osteoarthrosis (OA). Age, sex, serum sodium, potassium, creatinine, and comorbidities were recorded. We enrolled prospectively in-patients from our unit: age, sex, comorbidities, drugs, and fragility fractures were recorded. Blood electrolytes were measured. Cognitive function, nutrition, muscular strength, and balance were evaluated by standard tests. The mortality rate was recorded with a follow-up after hospital discharge.

RESULTS

The retrospective study included 2166 subjects: 702 Fx and 1464 controls (907 AMI, 557 OA): the prevalence of hyponatremia was similar in Fx and AMI, whereas it was higher in Fx with respect to OA (p < 0.001) as well as hypokalemia (p < 0.001). Sodium decrease was associated with higher fracture risk. Among the 284 subjects included in the prospective study, 50 patients were hyponatremic, more likely malnourished, and presented a higher prevalence of fragility fractures (p = 0.008). They had a higher mortality after hospital discharge (HR = 1.80, p = 0.005), however, this association disappears after correction for confounding variables.

CONCLUSIONS

We suggest that hyponatremia and hypokalemia have to be considered as a marker of poor health more than an independent fracture risk.

Association between diuretic use and the risk of vertebral fracture after stroke: a population-based retrospective cohort study

Background

Stroke is a major risk factor for osteoporosis and fractures. No study has evaluated the association between diuretic use and risk of vertebral fracture in stroke patients, although a considerable proportion of stroke patients are prescribed diuretics for hypertension. Our study aimed to investigate whether treatment with thiazides or loop diuretics affects the risk of vertebral fracture after stroke.

Methods

A population-based propensity score-matched retrospective cohort study was conducted using the Taiwan National Health Insurance Research Database. Patients with a new diagnosis of stroke between 2000 and 2011 were included. After propensity score matching, 9468 patients were included in the analysis of the effect of thiazides, of who 4734 received thiazides within 2 years after stroke. To analyze the loop diuretic effect, 4728 patients were included, of who 2364 received loop diuretics. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) of vertebral fractures among patients according to thiazide or loop diuretic use within 2 years following stroke. Sensitivity analyses based on the duration of thiazide or loop diuretic use were further conducted.

Results

There was no significant difference in vertebral fracture risk between thiazide users and non-users (adjusted HR [aHR] = 1.14, 95% confidence interval [CI] = 0.88–1.47, p = 0.316). Loop diuretic users had a significantly higher vertebral fracture risk than non-users (aHR = 1.45, 95% CI = 1.06–1.98, p = 0.019). However, the sensitivity analysis revealed that short-term thiazide use (exposure duration < 90 days within 2 years after stroke) significantly increased the risk of vertebral fracture versus non-use (aHR = 1.38, 95% CI = 1.02–1.88, p = 0.039). Only short-term loop diuretic users had significantly higher risk of vertebral fracture (aHR = 1.56, 95% CI = 1.11–2.20, p = 0.011). The other two subgroups with longer exposure duration in analyses for both thiazides and loop diuretics revealed no significant effect.

Conclusions

Short-term thiazide or loop diuretic use was associated with an increased risk of vertebral fracture after stroke. Further prospective clinical trials are required to confirm this finding.

Hyponatremia, falls and bone fractures: A systematic review and meta-analysis

OBJECTIVE

To perform a meta-analysis based on published studies that compared falls and bone fractures between patients with and without hyponatremia.

CONTEXT

There is evidence suggesting that hyponatremia is associated with an increased risk of falls and bone fractures.

DESIGN

An extensive Medline, Embase and Cochrane search was performed to retrieve all studies published up to, 30 April 2017, using the following words: "hyponatremia" or "hyponatraemia" AND "falls" and "bone fractures." A meta-analysis was performed including all studies comparing falls and bone fractures in subjects with or without hyponatremia.

PATIENTS AND RESULTS

Of 216 retrieved articles, 15 studies satisfied inclusion criteria encompassing a total of 51 879 patients, of whom 2329 were hyponatremic. Across all studies, hyponatremia was associated with a significantly increased risk of falls (MH-OR = 2.14[1.71; 2.67]. This result was confirmed when only hospitalized patients were considered (MH-OR = 2.44 [1.97; 3.02]). A meta-regression analysis showed that the hyponatremia-related risk of falls was higher in those studies considering a lower serum [Na+ ] cut-off to define hyponatremia. Interestingly, the estimated risk of falls related to hyponatremia was already significantly higher when a serum [Na+ ] cut-off of 135 mmol/L was considered (MH-OR = 1.26[1.23;1.29]). The presence of hyponatremia was also associated with a higher risk of fractures, particularly hip fractures (MH-OR = 2.00[1.43;2.81]).

CONCLUSIONS

This study confirms that hyponatremia is associated with an increased risk of falls and bone fractures. The clinical, social and economic relevance of such association is strengthened by the increased incidence of hyponatremia in older people.

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.

Diuretic Use and Risk of Vertebral Fracture in Women

BACKGROUND

Vertebral fracture is the most common type of osteoporotic fracture. While thiazide diuretics, which are commonly prescribed for the treatment of hypertension, decrease calciuria, they may also induce hyponatremia, which has been associated with increased vertebral fracture risk. Loop diuretics increase calciuria, which would reduce bone mineral density and increase vertebral fracture risk, but they rarely cause hyponatremia. Recent studies on diuretics and fractures did not include or specifically examine vertebral fracture. The few studies of diuretics and vertebral fracture have been limited by cases defined by self-report or administrative data, relatively small number of cases, study design that was not prospective, and lack of long-term follow-up with updated information on diuretic use.

METHODS

We conducted a prospective cohort study of thiazide diuretic use, loop diuretic use, and risk of incident clinical vertebral fracture in 55,780 women, 55-82 years of age, participating in the Nurses' Health Study, without a prior history of any fracture. Diuretic use was assessed by questionnaire every 4 years. Self-reported vertebral fracture was confirmed by medical record review. Cox proportional-hazards models were used to simultaneously adjust for potential confounders.

RESULTS

Our analysis included 420 incident vertebral fracture cases documented between 2002 and 2012. The multivariate-adjusted relative risk of clinical vertebral fracture for women taking thiazides compared with women not taking thiazides was 1.47 (95% confidence interval, 1.18-1.85). The multivariate adjusted relative risk of vertebral fracture for women taking loop diuretics compared with women not taking loop diuretics was 1.59 (95% confidence interval, 1.12-2.25).

CONCLUSION

Thiazide diuretics and loop diuretics are each independently associated with increased risk of vertebral fracture in women.

Antidepressants and the risk of hyponatremia: a Danish register-based population study

OBJECTIVE

To examine the association between classes of antidepressants and hyponatremia, and between specific antidepressants and hyponatremia.

DESIGN

Retrospective register-based cohort study using nationwide registers from 1998 to 2012.

SETTING

The North Denmark Region.

PARTICIPANTS

In total, 638 352 individuals were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Plasma sodium was obtained from the LABKA database. The primary outcome was hyponatremia defined as plasma sodium (p-sodium) below 135 mmol/L and secondary outcome was severe hyponatremia defined as p-sodium below 130 mmol/L. The association between use of specific antidepressants and hyponatremia was analysed using multivariable Poisson regression models.

RESULTS

An event of hyponatremia occurred in 72 509 individuals and 11.36% (n=6476) of these events happened during treatment with antidepressants. Incidence rate ratios and CIs for the association with hyponatremia in the first p-sodium measured after initiation of treatment were for citalopram 7.8 (CI 7.42 to 8.20); clomipramine 4.93 (CI 2.72 to 8.94); duloxetine 2.05 (CI 1.44 to 292); venlafaxine 2.90 (CI 2.43 to 3.46); mirtazapine 2.95 (CI 2.71 to 3.21); and mianserin 0.90 (CI 0.71 to 1.14).

CONCLUSIONS

All antidepressants except mianserin are associated with hyponatremia. The association is strongest with citalopram and lowest with duloxetine, venlafaxine and mirtazapine.

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.

Tolvaptan and Neurocognitive Function in Mild to Moderate Chronic Hyponatremia: A Randomized Trial (INSIGHT)

BACKGROUND

This trial assessed the effect of tolvaptan on cognition, gait, and postural stability in adult patients with mild to moderate asymptomatic hyponatremia.

STUDY DESIGN

Phase 3b, multicenter, randomized, double-blind, placebo-controlled, parallel-group pilot study.

SETTING & PARTICIPANTS

57 men and women 50 years or older with chronic asymptomatic euvolemic or hypervolemic hyponatremia (serum sodium concentration >120-<135 mEq/L) at 16 sites.

INTERVENTION

Patients were randomly assigned 1:1 to receive tolvaptan or matching placebo beginning at a dose of 15mg/d, with titration to 30 or 60mg/d based on change in serum sodium concentration and tolerance.

OUTCOMES

Primary: change from baseline in the neurocognitive composite score of speed domains. Secondary: changes from baseline in individual neurocognitive domain scores, overall neurocognitive composite score, gait and postural stability test results, and serum sodium concentrations.

RESULTS

Mean serum sodium concentration increased from 129 to 136 mEq/L in the tolvaptan group and from 130 to 132 mEq/L in the placebo group (P<0.001). There was no difference in overall neurocognitive composite scores of speed domains between groups, except for the psychomotor speed domain, which was statistically improved following hyponatremia correction with tolvaptan (treatment effect, 0.27; 95% CI, 0.04-0.51; P=0.03).

LIMITATIONS

There were some imbalances between treatment groups in baseline neurocognitive function scores and some baseline test results were near normal, leaving little opportunity for improvement. Formal sample size calculations were not performed because this was a pilot study. The study population was small (n=57) and treatment was of short duration (3 weeks). The primary end point of the study was not significant; thus, subgroup analyses are subject to errors of multiplicity and should be regarded as hypothesis generating.

CONCLUSIONS

Tolvaptan was effective in reversing chronic hyponatremia, and this correlated with improvements in results of a variety of neurocognition tests, particularly rapid motor movements, which tended to reverse following return to a low baseline serum sodium concentration after treatment withdrawal.

Neuronal distress induced by low extracellular sodium in vitro is partially reverted by the return to normal sodium

BACKGROUND

Hyponatremia is associated with negative clinical outcomes even when chronic and mild. It is also known that hyponatremia treatment should be appropriately performed, to avoid dramatic consequences possibly leading to death. We have previously demonstrated that chronically low extracellular [Na(+)], independently of reduced osmolality, is associated with signs of neuronal cell distress, possibly involving oxidative stress.

AIM

The aim of the present study was to assess whether the return to normal extracellular [Na(+)] is able to revert neuronal cell damage.

METHODS

After exposing SH-SY5Y and SK-N-AS cells to low [Na(+)] and returning to normal [Na(+)], we analyzed cell viability by MTS assay, ROS accumulation by FASCan and expression of anti-apoptotic genes.

RESULTS

We found that the viability of cells was restored upon return to normal [Na(+)]. However, when more subtle signs of cell distress were assessed, such as the expression level of the anti-apoptotic genes Bcl-2 and DHCR24 or of the heme oxygenase 1 gene, a complete return to basal values was not observed, in particular in SK-N-AS, even when [Na(+)] was gradually increased. We also demonstrated that the amount of ROS significantly increased in low [Na(+)], thus confirming that oxidative stress appears to contribute to the effects of low [Na(+)] on cell homeostasis.

CONCLUSIONS

Overall, this study provided the first demonstration that the correction of chronically low extracellular [Na(+)] may not be able to revert all the cell alterations associated with reduced [Na(+)]. These results suggest that prompt hyponatremia treatment might prevent possible residual abnormalities.

Hyponatremia and hypernatremia are associated with increased 30-day mortality in hip fracture patients

Using data from the Danish national registries on 7317 patients, this study shows that abnormal plasma sodium levels, in the form of hyponatremia and hypernatremia, are prevalent and associated with increased 30-day mortality in hip fracture patients.

INTRODUCTION

The aim of this study was to examine the prevalence of hyponatremia and hypernatremia in patients admitted with a fractured hip as well as the association with 30-day in mortality in these patients.

METHODS

A total of 7317 hip fracture patients (aged 60 years or above) with admission plasma sodium measurements were included. Data on comorbidity, medication, and death was retrieved from Danish national registries. The association between plasma sodium and mortality was examined using Cox proportional hazard models.

RESULTS

The prevalence of hyponatremia and hypernatremia on admission was 19.0 and 1.7 %, respectively. Thirty-day mortality was increased for patients with hyponatremia (12.2 %, p = 0.005) and hypernatremia (15.5 %, p = 0.03) compared to normonatremic patients (9.6 %). After adjustment for possible confounding factors, hyponatremia (1.38 [1.16-1.64], p = 0.0003) and hypernatremia (1.71 [1.08-2.70], p = 0.02) were still associated with increased risk of death by 30 days. Looking at the association between changes in plasma sodium during admission and mortality, there was no difference between patients with normalized and persistent hyponatremia (10.4 vs 11.3 %, p = 0.6) while a lower mortality was found for normalized hypernatremia compared to persistent hypernatremia (12.4 vs 33.3 %, p = 0.03).

CONCLUSIONS

This study shows that abnormal plasma sodium levels are prevalent in patients admitted with a fractured hip and that both hyponatremia and hypernatremia are associated with increased risk of death within 30 days of admission.

Hyponatremia and osteoporosis: reappraisal of a novel association

Age was a modifier of the independent association between hyponatremia and osteoporosis (OP). Risk of OP was the highest in the youngest age group as compared to older patients. A longer duration of hyponatremia revealed a similar association with OP in all anatomical sites.

INTRODUCTION

Epidemiologic studies provide conflicting results on the relationship between hyponatremia and OP. Our aim is to test the modification effect of age on the relationship between hyponatremia and OP at various anatomical sites in a large patient population.

METHODS

This is a cross-sectional observation of consecutive patients with available bone densitometry, demographic, clinical, and laboratory data from 2001 to 2013 at a single center. OP was defined as a bone mineral density of ≤2.5 standard deviations below the mean peak bone mass of young, healthy adults. Hyponatremia was defined as serum sodium ≤135 mmol/L. Multiple logistic regressions were used to calculate adjusted odds ratio (OR).

RESULTS

Overall, 24,784 patients were included. There were 4549 males (18.4 %). Hyponatremia was present in 703 patients (2.8 %), femoral neck OP in 2603 (10.5 %), total hip OP in 1885 (7.5 %), and lumbar OP in 4830 (19.5 %). Total hip OP occurred in 17.6 % (n = 124) of patients with hyponatremia as compared to 6.6 % (n = 880) of patients with sodium level of "140-145" mmol/L (P < 0.001). After multivariable adjustments, hyponatremia was associated with 2.46-fold higher odds of total hip OP (95 % CI, 1.36 to 4.46) in age <55 years, 1.96-fold (1.13 to 3.41) in age 55 to 67 years, and 1.55-fold (1.13 to 2.12) in age >67 years (age-sodium category interaction P value = 0.002).

CONCLUSIONS

Age appeared as a modifier of the independent association between hyponatremia and OP. Risk of OP was the highest in the youngest age group as compared to older patients.

Analysis of hyponatraemia associated post-operative mortality in 3897 hip fracture patients

Hyponatraemia is common in hospitalised patients. In recent years the relationship between hyponatraemia and bone metabolism, falls and fractures has become more established. This study evaluates the prevalence of hyponatraemia (plasma sodium<135mmol/l) in 3897 patients undergoing operative treatment for hip fracture and the relationship between hyponatraemia and mortality in these patients. Hyponatraemia was an independent risk factor for increased post-operative mortality on multivariate analysis. Median age at admission was 83 years. Hyponatraemia was present in 19.1% of patients with hip fracture on admission, 29.5% of patients in the first 24h post-operatively and 20% of patients at discharge. There was a significant association between hyponatraemia and time from admission to surgery indicating that patients admitted with hyponatraemia waited longer. The median follow-up time was 863 (range 0-4352) days. There were 2460 deaths (63.1% of the original 3897 patients) prior to the censor date. A total of 1144 patients (29.4% of the original 3897 patients) died within 12 months of discharge. Median time to death for patients with and without hyponatraemia on admission was 34 months (SE 1.7 months) and 41 months (SE 2.5 months) respectively (p=0.003). Median time to death for patients with and without hyponatraemia within 24h post-operatively was 35 months (SE 2.5 months) and 42 months (SE 1.7 months) respectively (p=0.004). Following elimination of other independent variables associated with increased mortality, hyponatraemia on admission was associated with an increased risk of death (adjusted HR 1.15, p=0.005). Post-operative hyponatraemia was also associated with an increased risk of death (adjusted HR 1.15, p=0.006). Trends suggested that hyponatraemia within 48h of discharge was associated with an increased risk of death (adjusted HR 1.15, p=0.636). Hyponatraemia is common in elderly patients with hip fractures both at initial presentation and during admission. In this vulnerable patient group, hyponatraemia may delay time to definitive surgery and is a potentially reversible cause of increased post-operative mortality. Every effort should be made to identify and correct hyponatraemia in hip fracture patients.

Hyponatremia and Fractures: Findings From the MrOS Study

Hyponatremia may be a risk factor for fracture. To determine the relationship between hyponatremia and fracture we conducted cross-sectional and longitudinal analyses using data from the Osteoporotic Fractures in Men (MrOS) study. The MrOS study enrolled 5122 community dwelling men aged ≥65 years from six centers across the United States. We excluded men taking bisphosphonates, those with unknown medication history, those without serum sodium measures, or those with out of range assays for serum sodium. Serum sodium was measured at study entry. Subjects were followed for fractures (nonspine [including hip], hip, incident morphometric, and prevalent morphometric) for up to 9 years. We used Cox proportional hazards models to analyze the association between serum sodium levels (<135 mmol/L versus ≥135 mmol/L) and risk of nonspine and hip fractures, with results presented as hazard ratios (HRs) and 95% confidence intervals (CIs). We examined the association between morphometric vertebral fractures and serum sodium using logistic regression models, presented as odds ratios (ORs) and 95% CI. Hyponatremia was observed in 64 men (1.2% of the cohort). After adjusting for age, BMI, study center, and other covariates, we found that, compared to men with serum sodium ≥135 mmol/L, those with serum sodium <135 mmol/L, had an increased risk of hip fracture (HR = 3.04; 95% CI, 1.37 to 6.75), prevalent morphometric spine fracture (OR = 2.46; 95% CI, 1.22 to 4.95), and incident morphometric spine fracture (OR = 3.53; 95% CI, 1.35 to 9.19), but not nonspine fracture (OR = 1.44; 95% CI, 0.85 to 2.44). Adjusting for bone mineral density (BMD) did not change our findings. Our data show that hyponatremia is associated with up to a doubling in the risk of hip and morphometric spine fractures, independent of BMD. Further studies, to determine how hyponatremia causes fractures and if correction of hyponatremia decreases fractures, are needed.

Dehydration, Hypernatremia, and Hyponatremia

Disturbances of serum sodium are one of the most common findings in older persons. They are also a major cause of hospital admissions and delirium and are associated with frailty, falls, and hip fractures. Both hypernatremia and hyponatremia are potentially preventable. Treatment involves treating the underlying cause and restoring sodium and volume status to normal. The arginine vasopressin antagonists, vaptans, have increased the therapeutic armamentarium available to physicians.

Relationship between Decrease in Serum Sodium Level and Bone Mineral Density in Osteoporotic Fracture Patients

Background

Recently, it has been suggested that decrease in serum sodium level is associated with osteoporosis. However, no study in Korea has reported the association of decrease in serum sodium level with osteoporosis. In this study, we investigated the relationship between the decrease in serum sodium level and severity of osteoporotic fracture in patients.

Methods

We enrolled 290 subjects who were admitted and operated at Soonchunhyang University Hospital due to major fractures. For the control group, we enrolled 1,027 subjects who visited a health promotion center. We carried a 1:1 matching with age and sex from the case group.

Results

In a total of 164 age- and sex-matched subjects, serum sodium level was significantly lower in the fracture group than in the non-fracture group (P=0.001). Serum sodium level was significantly lower in the severe osteoporosis group than that in the non-severe osteoporosis group (P=0.002). Old age and decrease in serum sodium level were independent risk factors of osteoporosis (odds ratio [OR]=1.088, P=0.008, confidence interval [CI]=[1.022-1.157]; OR= 0.840, P=0.037, CI=0.713-0.989).

Conclusions

Serum sodium level was significantly lower in the fracture group than that in the non-fracture group and in the severe osteoporosis group than that in the non-severe osteoporosis group. Based on our results, the decrease in serum sodium level could be an independent risk factor for osteoporosis.

Hyponatraemia in cancer patients on an inpatient rehabilitation unit

This study identifies the incidence of hyponatraemia in cancer patients on an inpatient rehabilitation unit and examines the association between admission hyponatraemia and rehabilitation length of stay (LOS), functional outcome, and survival. After institutional review committee's approval, we retrospectively reviewed medical records of 295 consecutive patients who were admitted to this inpatient cancer rehabilitation unit between 27 January 2009 through 31 July 2010 in a tertiary cancer centre. The incidence of hyponatraemia in cancer patients admitted to our inpatient rehabilitation unit was 41.4%. Median rehabilitation LOS for patients with mild (Na 130-134 mEq/L) and moderate-severe (Na < 130 mEq/L) hyponatraemia was 11 and 15 days, respectively, which was significantly longer than patients with eunatraemia (10 days; P = 0.03). Functional Independence Measure gain for ambulation and transfers during inpatient rehabilitation stay was not significantly different between three different patient groups. We concluded that large portion of patients who require acute inpatient rehabilitation presented with hyponatraemia, which is associated with prolonged rehabilitation LOS. Whether aggressive management of hyponatraemia will shorten rehabilitation stay needs further study.

Age-associated abnormalities of water homeostasis

Findley first proposed the presence of age-related dysfunction of the hypothalamic-neurohypophyseal-renal axis more than 60 years ago. More sophisticated studies have since corroborated his findings. As a result, it is now clear that multiple abnormalities in water homeostasis occur commonly with aging, and that the elderly are uniquely susceptible to disorders of body volume and osmolality. This article summarizes the distinct points along the hypothalamic-neurohypophyseal-renal axis where these changes have been characterized, as well as the clinical significance of these changes, with special attention to effects on cognition, gait instability, osteoporosis, fractures, and morbidity and mortality.

Hyponatremia at admission is associated with in-hospital death in patients with hip fracture

PURPOSE

Hyponatremia in hospitalized patients has been reported to be associated with in-hospital mortality. We studied patients treated at our hospital for hip fracture regarding the factors related to hyponatremia at admission.

METHODS

Among 580 patients aged 60 years or above who were admitted to our hospital since January 1997 for treatment of hip fracture, 512 patients (110 males, 402 females) from whom serum sodium level at admission was available were studied. In 512 patients, the age at injury ranged from 60 to 103 (mean 82.6) years. Fracture types were femoral neck fracture in 191 patients, and trochanteric fracture in 321. These patients were divided into two groups by the blood sodium level at admission: a hyponatremia group with sodium levels lower than 135 mEq/L, and a normonatremia group with sodium levels within normal range. The age, gender, fracture type, residence before injury, pre-injury walking capability, anemia at admission, liver function, kidney function, inflammatory status, urinary glucose status, lung disease, ECG abnormality, systemic chronic disease, status of dementia, treatment modality, hospital stay (days), and in-hospital death were investigated. First a univariate study was conducted to identify the factors that differ significantly between the two groups. Then multivariate analysis was conducted using the parameters with significant difference as independent variables

RESULTS

Hyponatremia was found in 49 of 512 (9.6 %) patients. In univariate analyses, six factors (age; residence before injury; anemia; dementia; treatment modality; in-hospital death) were significantly different between the hyponatremia group and normonatremia group. Multivariate analysis identified in-hospital death [odds ratio (OR) = 3.64, p = 0.035] and age (OR = 1.05, p = 0.029) as independently associated with hypernatremia.

CONCLUSION

Hyponatremia at admission is prevalent in old aged patients with fracture, and is related to in-hospital death.

Is chronic hyponatremia a novel risk factor for hip fracture in the elderly?

Hip fractures represent a serious health risk in the elderly, with significant associated morbidity and mortality. There is now an emerging literature that suggests that chronic hyponatremia increases the adjusted odds ratio (OR) for both falls and fractures in the elderly. Hyponatremia appears to contribute to falls and fractures by two mechanisms: (i) it produces mild cognitive impairment resulting in unsteady gait and falls and (ii) it directly contributes to osteoporosis and increased bone fragility by inducing increased bone resorption to mobilize sodium. There is debate over the effect of hyponatremia on the production of osteoporosis, as one study found decreased bone mineral density (BMD) and another did not. Should we be screening for low serum sodium in patients with osteoporosis or assessing BMD in patients with hyponatremia? The final answer is yet to come from prospective studies that allocate elderly individuals with mild hyponatremia to receive active treatment or not for hyponatremia and see if this intervention prevents gait disturbances and changes in BMD reducing fracture risk. In the meantime, physicians caring for elderly patients must be aware of the association between hyponatremia and bone problems. As serum sodium is a readily available, simple and affordable biochemical measurement, clinicians should look for hyponatremia in elderly patients who take medications that can cause hyponatremia. Also, elderly patients with unsteady gait and/or confusion should be checked for the presence of mild hyponatremia and if present it should not be ignored. Finally, elderly patients presenting with an orthopedic injury should have serum sodium checked and corrected if hyponatremia is present.

Hyponatremia and mortality: moving beyond associations

Acute hyponatremia can cause death if cerebral edema is not treated promptly. Conversely, if chronic hyponatremia is corrected too rapidly, osmotic demyelination may ensue, which also potentially is lethal. However, these severe complications of hyponatremia are relatively uncommon and often preventable. More commonly, hyponatremia predicts mortality in patients with advanced heart failure or liver cirrhosis. In these conditions, it generally is assumed that hyponatremia reflects the severity of the underlying disease rather than contributing directly to mortality. The same assumption holds for the recently reported associations between hyponatremia and mortality in patients with pulmonary embolism, pulmonary hypertension, pneumonia, and myocardial infarction. However, recent data suggest that chronic and mild hyponatremia in the general population also are associated with mortality. In addition, hyponatremia has been associated with mortality in long-term hemodialysis patients without residual function in whom the underlying disease cannot be responsible for hyponatremia. These new data raise the question of whether hyponatremia by itself can contribute to mortality or it remains a surrogate marker for other unknown risk factors. We review hyponatremia and mortality and explore the possibility that hyponatremia perturbs normal physiology in the absence of cerebral edema or osmotic demyelination.

Hyponatraemia: more than just a marker of disease severity?

Hyponatraemia--the most common serum electrolyte disorder--has also emerged as an important marker of the severity and prognosis of important diseases such as heart failure and cirrhosis. Acute hyponatraemia can cause severe encephalopathy, but the rapid correction of chronic hyponatraemia can also profoundly impair brain function and even cause death. With the expanding elderly population and the increased prevalence of hyponatraemia in this segment of society, prospective studies are needed to examine whether correcting hyponatraemia in the elderly will diminish cognitive impairment, improve balance and reduce the incidence of falls and fractures. Given that polypharmacy is also common in the elderly population, the various medications that may stimulate arginine vasopressin release and/or enhance the hormone's action to increase water absorption must also be taken into consideration. Whether hyponatraemia in a patient with cancer is merely a marker of poor prognosis or whether its presence may alter the patient's quality of life remains to be examined. In any case, hyponatraemia can no longer be considered as just a biochemical bystander in the ill patient. A systematic diagnostic approach is necessary to determine the specific aetiology of a patient's hyponatraemia. Therapy must then be dictated not only by recognized reversible causes such as advanced hypothyroidism, adrenal insufficiency, diuretics or other medicines, but also by whether the hyponatraemia occurred acutely or chronically. Information is emerging that the vast majority of cases of hyponatraemia are caused by the nonosmotic release of arginine vasopressin. Now that vasopressin V2-receptor blockers are available, a new era of clinical investigation is necessary to examine whether hyponatraemia is just a marker of severe disease or whether correction of hyponatraemia could improve a patient's quality of life. Such an approach must involve prospective randomized studies in different groups of patients with hyponatraemia, including those with advanced heart failure, those with cirrhosis, patients with cancer, and the elderly.

Antidepressant medications and osteoporosis

Use of antidepressant medications that act on the serotonin system has been linked to detrimental impacts on bone mineral density (BMD), and to osteoporosis. This article reviews current evidence for such effects, and identifies themes for future research. Serotonin receptors are found in all major types of bone cell (osteoblasts, osteocytes, and osteoclasts), indicating an important role of the neuroendocrine system in bone. Observational studies indicate a complex relationship between depression, antidepressants, and fracture. First, the presence of depression itself increases fracture risk, in relation with decreased BMD and an increase in falls. A range of aspects of depression may operate, including behavioral factors (e.g., smoking and nutrition), biological changes, and confounders (e.g., comorbidities and concomitant medications). A substantial proportion of depressed patients receive antidepressants, mostly selective serotonin reuptake inhibitors (SSRIs). Some of these have been linked to decreased BMD (SSRIs) and increased fracture risk (SSRIs and tricyclic agents). Current use of SSRIs and tricyclics increases fracture risk by as much as twofold versus nonusers, even after adjustment for potential confounders. While there is a dose-response relationship for SSRIs, the effect does not appear to be homogeneous across the whole class of drugs and may be linked to affinity for the serotonin transporter system. The increase in risk is the greatest in the early stages of treatment, with a dramatic increase after initiation, reaching a peak within 1 month for tricyclics and 8 months for SSRIs. Treatment-associated increased risk diminishes towards baseline in the year following discontinuation. The body of evidence suggests that SSRIs should be considered in the list of medications that are risk factors for osteoporotic fractures.