Outcomes in Severe Hyponatremia Treated With and Without Desmopressin

Rapid-onset hypernatremia induced by central diabetes insipidus leading to osmotic demyelination syndrome: a case report

This case study describes a middle-aged male patient who developed persistent hypernatremia due to central diabetes insipidus (CDI), presenting with polyuria (up to 8.5 L/24 h), polydipsia, and hypotonic urine (urine specific gravity < 1.005). A positive response to the desmopressin test confirmed the diagnosis of CDI. The excessive loss of body water led to a peak serum sodium level of 195 mmol/L, resulting in Osmotic demyelination syndrome (ODS), clinically manifesting as sluggish responses and symmetrical limb paralysis. The patient was treated with hypotonic fluid replacement combined with desmopressin while ensuring a controlled reduction in serum sodium levels (≤10 mmol/L within 24 h). As a result, as serum sodium and urine output gradually normalized, the patient's consciousness and limb strength progressively recovered. This case highlights the risk of ODS in patients with severe hypernatremia caused by CDI. A slow and controlled correction of serum sodium levels is crucial in preventing cerebral edema, and early rehabilitation plays a vital role in improving neurological outcomes.

Exercise-associated Hyponatremia Developing Immediately after a Musical Stage Performance in a Healthy Actress

Exercise-associated hyponatremia (EAH) is a life-threatening dilutional hyponatremia that typically occurs during or immediately after exercise in endurance athletes. A 49-year-old actress experienced dizziness 15 min after a 2-h stage performance while drinking several bottles of water. Thirty minutes later, the patient fell unconscious and was hospitalized. On admission, she showed dilutional hyponatremia (117 mmol/L) with extremely elevated arginine vasopressin (11.3 pg/mL). After initial treatment with 3% saline, her sodium levels immediately increased, and she recovered consciousness without developing subsequent osmotic demyelination syndrome. This case emphasizes the need for caution against excessive fluid intake during and/or after exercise to avoid EAH, even in non-athletes.

The risk of sodium overcorrections in severe hyponatremia and the utility of desmopressin: a large retrospective study

Background

The suggested narrow rate of serum sodium (sNa) correction in hyponatremia can be difficult to respect, leading to overcorrections. Our ability to anticipate the rapidity of correction according to the mechanism of hyponatremia is uncertain. While desmopressin is often used to pause a rapid rise in sNa, its dose-related effect is also not well described. We studied the rate of hyponatremia overcorrections, its prediction and the utility of desmopressin in its management.

Methods

We retrospectively reviewed all cases of severe hyponatremia (sNa <120 mmol/L) in a large university hospital that occurred over 10 years. We assessed investigations, causes and treatments. We compared all sNa separated by at least 8 h and calculated correction rates. Significant overcorrection rates were defined by any rise of sNa >9 mmol/L per day sustained over at least 24 h.

Results

After exclusions, we found 355 episodes of severe hyponatremia. Low, appropriate and inappropriate antidiuretic hormone (ADH)-defined mechanisms accounted for 17%, 24% and 29% of etiologies, respectively, with the remaining 25% secondary to diuretics and 5% of uncertain causes. First urinary sodium and osmolality were consistent with the final diagnosis in 73%. Significant overcorrections were seen in 45% and were frequent in the setting of low ADH. Desmopressin was given in 82 episodes, more often as a rescue than a preventive measure, with the subsequent sNa dropping by ≥5 mmol/L by 12 h in eight instances. The dose of desmopressin (≥2 µg versus 1 µg) and a higher volume of intravenous free-water coadministration resulted in a clinically meaningful greater reduction in sNa in the following 12 h.

Conclusions

Overcorrections in severe hyponatremia are common, mainly when ADH is low. Initial urinary measurements anticipate this risk. Desmopressin effectively halted the rate of correction in a dose-dependent manner. Caution should be given when coadministrating water, which can significantly lower the sNa.

Correction of profound hyponatraemia following rapid bolus therapy: effectiveness of the Barsoum-Levine formula based on the Edelman equation

Background

The optimal treatment for profound hyponatraemia remains uncertain. Recent clinical studies have demonstrated that a standardized bolus of hypertonic saline is effective, but relying solely on this approach may not fully address the individual variability of hyponatraemia among patients. We evaluated the effectiveness of rapid bolus (RB) administration of hypertonic saline followed by predictive correction (PC) using an infusate and fluid loss formula identical to the Barsoum-Levine formula based on the Edelman equation (RB-PC) for managing profound hyponatraemia.

Methods

In this retrospective observational cohort study, we evaluated 276 patients aged >18 years with s[Na] levels ≤120 mEq/L (January 2014-December 2023). Using propensity score matching (PSM), we assessed s[Na] elevations at 6 h post-treatment initiation and the rate of appropriate hyponatraemia correction between the RB-PC and PC groups. We defined the appropriate correction as a change in s[Na] in the range of 4-10 mEq/L within the first 24 h and ≤18 mEq/L within the first 48 h following corrective treatment initiation.

Results

Among 276 patients with profound hyponatraemia (s[Na] ≤120 mEq/L), 49 and 108 underwent treatment with RB-PC therapy and with PC therapy without RB, respectively. Post-PSM, 84 patients were selected and allocated to the RB-PC (n = 42) or PC group (n = 42). In PSM analysis, patients with RB-PC experienced a higher elevation in s[Na] at 6 h after treatment initiation than PC (4.0 vs 2.4 mEq/L, P < 0.001). The rate of appropriate correction was similar between the RB-PC and PC groups (90.5% vs 90.5%, P = 1).

Conclusions

RB-PC can quickly elevate s[Na] levels and achieve appropriate correction of s[Na] in patients with profound hyponatraemia.

Safety and efficacy of proactive versus reactive administration of desmopressin in severe symptomatic hyponatremia: a randomized controlled trial

This randomized controlled trial aimed to evaluate the safety and efficacy of proactive versus reactive desmopressin (DDAVP) strategies in treating severe symptomatic hyponatremia. Conducted from June 20, 2022, to February 20, 2023, it involved 49 patients with serum sodium levels below 125 mmol/L. Patients were assigned to either the proactive group, receiving DDAVP immediately upon diagnosis, or the reactive group, receiving DDAVP only if the serum sodium level tended to be overcorrected. The primary outcome was the incidence of overcorrection. The study revealed no significant difference in the overcorrection incidence between the proactive (16.7%) and reactive (28%) groups (p = 0.54). The change in serum sodium levels at 1, 6, 12, and 24 h were not different, however, at 48 h, the proactive group exhibited a higher but still safe change in serum sodium levels compared to the reactive group (10.3 ± 3.6 mmol/L vs. 7.7 ± 3.6 mmol/L, p = 0.013). Other parameters including time to symptom improvement, total intravenous fluid administered, DDAVP dose, urine volume, hospital stay duration, osmotic demyelination syndrome incidence, and 28-day mortality did not significantly differ between the groups. In conclusion, our findings suggest that there was no significant disparity in overcorrection rates between proactive and reactive DDAVP strategies for treating severe symptomatic hyponatremia. However, further large-scale studies are warranted to validate these results.

[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.

Shikimic acid recovers diarrhea and its complications in SD rats fed lactose diet to induce diarrhea

BACKGROUND

Diarrhea is the increase of excretion of human water content and an imbalance in the physiologic processes of the small and large intestine while shikimic acid is an important biochemical metabolite in plants. This study aims to study the anti-diarrheal activity of shikimic acid through restoring kidney function, antioxidant activity, inflammatory markers, sodium/potassium-ATPase activity, apoptosis genes, and histology of the kidney in SD rats fed lactose diet to induce diarrhea.

RESULTS

Thirty-six male SD rats (150 ± 10 g, 12 weeks old) were divided into 2 equal groups (18 rats/group) as follows: normal and diarrheal rats. Normal rats were divided into 3 equal groups of 6 rats each: the control, shikimic acid, and desmopressin drug groups. Diarrheal rats were also divided into 3 equal groups of 6 rats each: diarrheal, diarrheal rats + shikimic acid, and diarrheal rats + desmopressin drug groups. Shikimic acid restored serum urea and creatinine, urinary volume, kidney weight, sodium, potassium, and chloride balance in serum and urine. The acid returned the antioxidant (superoxide dismutase, glutathione peroxidase, catalase, malondialdehyde, NADPH oxidase activity, conjugated dienes, and oxidative index) activity and the inflammatory markers (tumor necrosis factor-α, interleukin-1β, interleukin-6, and interleukin-10) to values approaching the control values. Shikimic acid also restored the sodium/potassium-ATPase activity, the apoptosis genes p53 and bcl-2, and the histology of kidney tissue in diarrheal rats to be near the control group.

CONCLUSIONS

Shikimic acid rescues diarrhea and its complications through restoring kidney function, serum and urinary electrolytes, antioxidant activity, inflammatory markers, sodium/potassium-ATPase activity, the apoptosis genes, and the histology of the kidney in diarrheal rats to approach the control one.

An Exchange about "Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia"

In Volume 2, Number 4 of NEJM Evidence, we published an article entitled, "Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia" by MacMillan et al. The article was accompanied by an editorial entitled "Hyponatremia Treatment Guidelines - Have They Gone Too Far?" by Ayus and Moritz. After these articles were published, a group of readers shared feedback about the data presented and the conclusions drawn; their comments are detailed as "Remarks from Readers." We relayed these points to the authors of the original article and the editorial; their responses follow.

Effects of correction rate for severe hyponatremia in the intensive care unit on patient outcomes

PURPOSE

Limited evidence exists regarding outcomes associated with different correction rates of severe hyponatremia.

MATERIALS AND METHODS

This retrospective cohort analysis employed a multi-center ICU database to identify patients with sodium ≤120 mEq/L during ICU admission. We determined correction rates over the first 24 h and categorized them as rapid (> 8 mEq/L/day) or slow (≤ 8 mEq/L/day). The primary outcome was in-hospital mortality. Secondary outcomes included hospital-free days, ICU-free days, and neurological complications. We used inverse probability weighting for confounder adjustment.

RESULTS

Our cohort included 1024 patients; 451 rapid and 573 slow correctors. Rapid correction was associated with lower in-hospital mortality (absolute difference: -4.37%; 95% CI, -8.47 to -0.26%), longer hospital-free days (1.80 days; 95% CI, 0.82 to 2.79 days), and longer ICU-free days (1.16 days; 95% CI, 0.15 to 2.17 days). There was no significant difference in neurological complications (2.31%; 95% CI, -0.77 to 5.40%).

CONCLUSION

Rapid correction (>8 mEq/L/day) of severe hyponatremia within the first 24 h was associated with lower in-hospital mortality and longer ICU and hospital-free days without an increase in neurological complication. Despite major limitations, including the inability to identify the chronicity of hyponatremia, the results have important implications and warrant prospective studies.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

[Hyponatremia : Etiology, diagnosis and acute therapy]

Hyponatremia is one of the most common electrolyte disorders in emergency departments and hospitalized patients. Serum sodium concentration is controlled by osmoregulation and volume regulation. Both pathways are regulated via the release of antidiuretic hormone (ADH). Syndrome of inappropriate release of ADH (SIADH) may be caused by neoplasms or pneumonia but may also be triggered by drug use or drug abuse. Excessive fluid intake may also result in a decrease in serum sodium concentration. Rapid alteration in serum sodium concentration leads to cell swelling or cell shrinkage, which primarily causes neurological symptoms. The dynamics of development of hyponatremia and its duration are crucial. In addition to blood testing, a clinical examination and urine analysis are essential in the differential diagnosis of hyponatremia.

Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia

BACKGROUND: Osmotic demyelination syndrome (ODS) is a rare but potentially devastating neurologic complication of hyponatremia. The primary objective of this study was to identify the proportion of patients who developed ODS in a large, contemporary, multicenter cohort of patients admitted to the hospital with hyponatremia. METHODS: We conducted a multicenter cohort study of patients admitted with hyponatremia at five academic hospitals in Toronto, Ontario, Canada, between April 1, 2010, and December 31, 2020. All adult patients presenting with hyponatremia (serum sodium level 8 mmol/l in any 24-hour period). RESULTS: Our cohort included 22,858 hospitalizations with hyponatremia. Approximately 50% were women, the average age was 68 years, and mean initial serum sodium was 125 mmol/l (standard deviation, 4.6), including 11.9% with serum sodium from 110 to 119 mmol/l and 1.2% with serum sodium less than 110 mmol/l. Overall, rapid correction of serum sodium occurred in 3632 (17.7%) admissions. Twelve patients developed ODS (0.05%). Seven (58%) patients who developed ODS did not have rapid correction of serum sodium. CONCLUSIONS: In this large multicenter study of patients with hyponatremia, rapid correction of serum sodium was common (n=3632 [17.7%]), but ODS was rare (n=12 [0.05%]). Future studies with a higher number of patients with ODS are needed to better understand potential causal factors for ODS.

Clinical Approach to Euvolemic Hyponatremia

Euvolemic hyponatremia is frequently encountered in hospitalized patients and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause in most patients. SIADH diagnosis is confirmed by decreased serum osmolality, inappropriately elevated urine osmolality (>100 mosmol/L), and elevated urine sodium (Na) levels. Patients should be screened for thiazide use and adrenal or thyroid dysfunction should be ruled out before making a diagnosis of SIADH. Clinical mimics of SIADH like cerebral salt wasting and reset osmostat should be considered in some patients. The distinction between acute (<48 hours) versus chronic (>48 hours or without baseline labs) hyponatremia and clinical symptomatology are important to initiate proper therapy. Acute hyponatremia is a medical emergency and osmotic demyelination syndrome (ODS) occurs commonly when rapidly correcting any chronic hyponatremia. Hypertonic (3%) saline should be used in patients with significant neurologic symptoms and maximal correction of serum Na level should be limited to <8 mEq over 24 hours to prevent the ODS. Simultaneous administration of parenteral desmopressin is one of the best ways to prevent overly rapid Na correction in high-risk patients. Free water restriction combined with increased solute intake (e.g., urea) is the most effective therapy to treat patients with SIADH. 0.9% saline acts as a hypertonic solution in patients with hyponatremia and should be avoided in the treatment of SIADH due to rapid fluctuations in serum Na levels. Dual effects of 0.9% saline resulting in rapid correction of serum Na during infusion (inducing ODS) and post-infusion worsening of serum Na levels are described in the article with clinical examples.

Korean Society of Nephrology 2022 recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Korean Society of Nephrology 2022 Recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Diagnosis and Management of Hyponatremia: A Review

IMPORTANCE

Hyponatremia is the most common electrolyte disorder and it affects approximately 5% of adults and 35% of hospitalized patients. Hyponatremia is defined by a serum sodium level of less than 135 mEq/L and most commonly results from water retention. Even mild hyponatremia is associated with increased hospital stay and mortality.

OBSERVATIONS

Symptoms and signs of hyponatremia range from mild and nonspecific (such as weakness or nausea) to severe and life-threatening (such as seizures or coma). Symptom severity depends on the rapidity of development, duration, and severity of hyponatremia. Mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures. In a prospective study, patients with hyponatremia more frequently reported a history of falling compared with people with normal serum sodium levels (23.8% vs 16.4%, respectively; P < .01) and had a higher rate of new fractures over a mean follow-up of 7.4 years (23.3% vs 17.3%; P < .004). Hyponatremia is a secondary cause of osteoporosis. When evaluating patients, clinicians should categorize them according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia). For most patients, the approach to managing hyponatremia should consist of treating the underlying cause. Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects (eg, poor palatability and gastric intolerance with urea; and overly rapid correction of hyponatremia and increased thirst with vaptans). Severely symptomatic hyponatremia (with signs of somnolence, obtundation, coma, seizures, or cardiorespiratory distress) is a medical emergency. US and European guidelines recommend treating severely symptomatic hyponatremia with bolus hypertonic saline to reverse hyponatremic encephalopathy by increasing the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours but by no more than 10 mEq/L (correction limit) within the first 24 hours. This treatment approach exceeds the correction limit in about 4.5% to 28% of people. Overly rapid correction of chronic hyponatremia may cause osmotic demyelination, a rare but severe neurological condition, which can result in parkinsonism, quadriparesis, or even death.

CONCLUSIONS AND RELEVANCE

Hyponatremia affects approximately 5% of adults and 35% of patients who are hospitalized. Most patients should be managed by treating their underlying disease and according to whether they have hypovolemic, euvolemic, or hypervolemic hyponatremia. Urea and vaptans can be effective in managing the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure; hypertonic saline is reserved for patients with severely symptomatic hyponatremia.

Hypertonic Saline for Hyponatremia: Meeting Goals and Avoiding Harm

Hypertonic saline has been used for the treatment of hyponatremia for nearly a century. There is now general consensus that hypertonic saline should be used in patients with hyponatremia associated with moderate or severe symptoms to prevent neurological complications. However, much less agreement exists among experts regarding other aspects of its use. Should hypertonic saline be administered as a bolus injection or continuous infusion? What is the appropriate dose? Is a central venous line necessary? Should desmopressin be used concomitantly and for how long? This article considers these important questions, briefly explores the historical origins of hypertonic saline use for hyponatremia, and reviews recent evidence behind its indications, dosing, administration modality and route, combined use with desmopressin to prevent rapid correction of serum sodium, and other considerations such as the need and degree for fluid restriction. The authors conclude by offering some practical recommendations for the use of hypertonic saline.

Osmotic Demyelination Syndrome following Correction of Hyponatremia by ≤10 mEq/L per Day

Background

Overly rapid correction of chronic hyponatremia may lead to osmotic demyelination syndrome. European guidelines recommend a correction to ≤10 mEq/L in 24 hours to prevent this complication. However, osmotic demyelination syndrome may occur despite adherence to these guidelines.

Methods

We searched the literature for reports of osmotic demyelination syndrome with rates of correction of hyponatremia ≤10 mEq/L in 24 hours. The reports were reviewed to identify specific risk factors for this complication.

Results

We identified 19 publications with a total of 21 patients that were included in our analysis. The mean age was 52 years, of which 67% were male. All of the patients had community-acquired chronic hyponatremia. Twelve patients had an initial serum sodium <115 mEq/L, of which seven had an initial serum sodium ≤105 mEq/L. Other risk factors identified included alcohol use disorder (n=11), hypokalemia (n=5), liver disease (n=6), and malnutrition (n=11). The maximum rate of correction in patients with serum sodium <115 mEq/L was at least 8 mEq/L in all but one patient. In contrast, correction was <8 mEq/L in all but two patients with serum sodium ≥115 mEq/L. Among the latter group, osmotic demyelination syndrome developed before hospital admission or was unrelated to hyponatremia overcorrection. Four patients died (19%), five had full recovery (24%), and nine (42%) had varying degrees of residual neurologic deficits.

Conclusion

Osmotic demyelination syndrome can occur in patients with chronic hyponatremia with a serum sodium <115 mEq/L, despite rates of serum sodium correction ≤10 mEq/L in 24 hours. In patients with severe hyponatremia and high-risk features, especially those with serum sodium <115 mEq/L, we recommend limiting serum sodium correction to <8 mEq/L. Thiamine supplementation is advisable for any patient with hyponatremia whose dietary intake has been poor.

Evaluation of Desmopressin in Critically Ill Patients with Hyponatremia Requiring 3% Hypertonic Saline

BACKGROUND

Desmopressin (DDAVP) is often used for hyponatremia management but has been associated with increases in hospital length of stay and duration of hypertonic saline use. The purpose of this study was to evaluate hyponatremia management strategies and their effect on sodium correction in critically ill patients requiring 3% hypertonic saline (3HS).

METHODS

This retrospective, single-center study included critically ill patients with hyponatremia (serum sodium ≤ 125 mEq/L) receiving 3HS from May 31 2015, to May 31 2019. Patients were divided into those who received 3HS for hyponatremia management (HTS) and those who received proactive or reactive DDAVP in addition to 3HS (D-HTS). Patients in either group could receive rescue DDAVP. The primary outcome was the percentage of patients achieving goal sodium correction of 5-10 mEq/L 24 h after 3HS initiation.

RESULTS

Goal sodium correction was achieved in 52.5% of patients in HTS compared to 65.6% of patients in D-HTS (p = 0.21). Patients in HTS had a shorter duration of 3HS infusion (p = 0.0022) with no difference in ICU length of stay, free water intake, urine output, or serum sodium increases 12 and 24 h after receiving 3HS. Overcorrection during any 24- or 48 h period was not statistically different between groups.

CONCLUSION

Patients in HTS and D-HTS had similar rates of achieving goal sodium correction at 24 h. A proactive or reactive DDAVP strategy led to an increase in 3HS duration and total amount with no significant difference in rates of overcorrection. Prospective, randomized studies assessing standardized strategies for hyponatremia management and DDAVP administration are warranted.

Association of intranasal desmopressin therapy with overcorrection of severe hyponatremia: A retrospective, propensity score-based, single-center cohort study

PURPOSE

Severe hyponatremia, defined as serum sodium concentration ([sNa]) ≤ 120 mEq/L, requires aggressive treatment to prevent potentially fatal cerebral edema, seizures, and other sequelae, but overcorrection can also result in life-threatening cerebral hemorrhage and demyelination. We compared the safety and efficacy of nasal desmopressin to conventional management for the prevention of [sNa] overcorrection.

MATERIAL AND METHODS

This retrospective analysis compared 47 patients treated with desmopressin to 17 patients treated conventionally at a university hospital ICU in Japan between 2013 and 2018 using propensity score-based approaches. The primary outcome was safe [sNa] correction, defined as a ≤ 8 mEq/L difference between baseline and follow-up [sNa] at any time within 24h of diagnosis.

RESULTS

The 24-h safe correction rate was significantly greater in the desmopressin group than the conventional treatment group (68% [32/47] vs. 41% [7/17], P = 0.039), and dose-response analysis indicated a positive association between cumulative 24-h desmopressin dose and safe correction at 24 h (P = 0.003). Few overcorrections precluded reliable assessment at 48 h. Exacerbation of hyponatremia was comparable in the two treatment groups.

CONCLUSIONS

Intranasal desmopressin therapy increased the safe correction of severe hyponatremia. Large prospective trials are warranted to confirm this result.

Effective treatment of osmotic demyelination syndrome with plasmapheresis: a case report and review of the literature

Background

Treatment options for chronic osmotic demyelination syndrome are limited to case reports and only a very few show complete recovery. We report a case of complete recovery of chronic osmotic demyelination syndrome with plasmapheresis.

Case presentation

A 43-year-old Sri Lankan man presented with fever, repeated vomiting, unsteady gait, increased tonicity of his right upper limb and paucity of speech for three days. He was treated in the local hospital with antibiotics and antivirals as per central nervous system infection. He had hyponatraemia, which was rapidly corrected with hypertonic saline from 97 to 119 mmol/L. He was transferred to our hospital because of progressive reduction of consciousness, rapidly worsening rigidity and bradykinesia of all four limbs and worsening dysarthria and bradyphrenia. Magnetic resonance imaging of the brain was compatible with osmotic demyelination syndrome. He was commenced on plasmapheresis twenty-two days after rapid correction of sodium. He regained independent mobility with complete resolution of rigidity, bradykinesia and speech dysfunction after five cycles of alternate day plasmapheresis.

Conclusion

Plasmapheresis can be considered as an effective treatment modality in chronic osmotic demyelination syndrome.

The Effect of the Dose of Isotonic Saline on the Correction of Serum Sodium in the Treatment of Hypovolemic Hyponatremia

BACKGROUND

Overcorrection of serum sodium (SNa) during therapy of hyponatremia can result in osmotic demyelination syndrome. Our aim was to determine the relationship between the isotonic saline solution dose (ISSD) administered and the 24-h SNa increase (24SNa) in patients with hypovolemic hyponatremia (HH).

METHODS

Retrospective study of HH patients treated with ISS in a tertiary hospital of Madrid, Spain, between 1 January-30 May 2019. The 24-h ISSD received and corresponding 24SNa were calculated. The latter was classified as 3 groups: ≥8 mmol/L, ≥6 mmol/L, or <4 mmol/L. Multivariate regression analyses were performed and ROC curves calculated to study the relationship between ISSD and 24SNa.

RESULTS

Thirty patients were included, age 72 years (60-80), 50% were women. 24SNa was ≥8 mmol/L/24 h in 33%, ≥6 mmol/L/24 h in 50%, and <4 mmol/L/24 h in 30%. Median ISSD in each group was: 32 mL/kg/24 h (29-37), 31 mL/kg/24 h (25-33), and 20 mL/kg/24 h (14-22), respectively. An ISSD ≥ 30 mL/kg/24 h had an odds ratio (OR) of 16 (95% CI: 2.5-95.1; p = 0.004) for a 24SNa ≥8 mmol/L, with a sensitivity and specificity of 80%.

CONCLUSIONS

The 24SNa depends on ISSD. An ISSD between 23-30 mL/kg/24 h seems to be safe and effective.

Criteria for Hyponatremic Overcorrection: Systematic Review and Cohort Study of Emergently Ill Patients

BACKGROUND

Hyponatremia is the most common electrolyte disturbance amongst hospitalized patients. An overly rapid rate of correction of chronic hyponatremia is believed to increase the risk of poor clinical outcomes including osmotic demyelination syndrome (ODS). There is disagreement in the literature regarding the definition of hyponatremic overcorrection.

METHODS

We performed a systematic review of all English language studies to identify those that calculated sodium correction rate and classified patients' overcorrection status. We then identified all patients who presented to our hospital's emergency department between 2003 and 2015 with a corrected serum sodium ≤ 116 mmol/L. All methods from the systematic review for sodium correction rate calculation and overcorrection status were applied to this cohort.

RESULTS

We identified 24 studies citing 9 distinct sodium correction rate methods and 14 criteria for overcorrection. Six hundred twenty-four patients presenting with severe hyponatremia (median initial value 113 mMol) were identified. Depending on the method used, the median sodium correction rates in our cohort ranged from 0.271 to 1.13 mmol/L per hour. The proportion of patients classified with overcorrection with the different criteria varied almost 11-fold, ranging from 8.5 to 89.9%.

CONCLUSION

Published methods disagree regarding the calculation of sodium correction rates and the definition of hyponatremic overcorrection. This leads to wide variations in sodium correction rates and the prevalence of overcorrection in patient cohorts. Definitions based on ODS risk are needed.

Derivation and Validation of a Novel Risk Score to Predict Overcorrection of Severe Hyponatremia: The Severe Hyponatremia Overcorrection Risk (SHOR) Score

BACKGROUND AND OBJECTIVES

Osmotic demyelination syndrome is the most concerning complication of severe hyponatremia, occurring with an overly rapid rate of serum sodium correction. There are limited clinical tools to aid in identifying individuals at high risk of overcorrection with severe hyponatremia.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We identified all patients who presented to a tertiary-care hospital emergency department in Ottawa, Canada (catchment area 1.2 million) between January 1, 2003 and December 31, 2015, with serum sodium (corrected for glucose levels) <116 mmol/L. Overcorrection was determined using 14 published criteria. Latent class analysis measured the independent association of baseline factors with a consensus overcorrection status on the basis of the 14 criteria, and was summarized as a risk score, which was validated in two cohorts.

RESULTS

A total of 623 patients presented with severe hyponatremia (mean initial value 112 mmol/L; SD 3.2). The prevalence of no, unlikely, possible, and definite overcorrection was 72%, 4%, 10%, and 14%, respectively. Overcorrection was independently associated with decreased level of consciousness (2 points), vomiting (2 points), severe hypokalemia (1 point), hypotonic urine (4 points), volume overload (-5 points), chest tumor (-5 points), patient age (-1 point per decade, over 50 years), and initial sodium level (<110 mmol/L: 4 points; 110-111 mmol/L: 2 points; 112-113 mmol/L: 1 point). These points were summed to create the Severe Hyponatremic Overcorrection Risk (SHOR) score, which was significantly associated with overcorrection status (Spearman correlation 0.45; 95% confidence interval, 0.36 to 0.49) and was discriminating (average dichotomized c-statistic 0.77; 95% confidence interval, 0.73 to 0.81). The internal (n=119) and external (n=95) validation cohorts had significantly greater use of desmopressin, which was significantly associated with the SHOR score. The SHOR score was significantly associated with overcorrection status in the internal (P<0.001) but not external (P=0.39) validation cohort.

CONCLUSIONS

In patients presenting with severe hyponatremia, overcorrection was common and predictable using baseline information. Further external validation of the SHOR is required before generalized use.

Use of Desmopressin in Hyponatremia: Foe and Friend

Use of desmopressin (1-deamino-8-d-arginine vasopressin; DDAVP), a synthetic vasopressin receptor agonist, has expanded in recent years. Desmopressin leads to renal water retention, and iatrogenic hyponatremia may result if fluid intake is not appropriately restricted. It is common practice to stop a medication that is causing toxicity, and this advice is promulgated in Micromedex, which suggests withholding desmopressin if hyponatremia occurs. If intravenous saline solution is administered and desmopressin is withheld at the same time, rapid changes in serum sodium levels may result, which puts the patient at risk for demyelinating lesions. In the management of desmopressin-associated hyponatremia with neurologic symptoms, the drug should not be withheld despite the presence of hyponatremia. The medication should be continued while administering intravenous hypertonic saline solution. Desmopressin is also used to minimize water excretion during the correction of hyponatremia during water diuresis. When treating hyponatremia, clinicians should monitor closely to avoid free-water diuresis. To prevent ongoing water losses in urine and overly rapid “autocorrection” of serum sodium level, desmopressin can be given to reduce free-water losses. These treatment recommendations are the authors’ perspective from previously published work and personal clinical experience.

Approach to and management of abnormalities in plasma sodium

The differential diagnosis between hypertonic, isotonic and hypotonic hyponatremia are presented. The help of some usual serum (urea, uric acid and TCO₂) and urine parameters (mainly osmolality and sodium concentration) are discussed and help to determine the best treatment. Morbidity associated with untreated hyponatremia and with the different treatment available is also discussed. Who to prevent and treat ODS (osmotic demyelating syndrome) is recalled. The pathophysiology and treatment of hypernatremia are also discussed.

Treatment of Severe Hyponatremia

Patients with severe (serum sodium ≤120 mEq/L), symptomatic hyponatremia can develop life-threatening or fatal complications from cerebral edema if treatment is inadequate and permanent neurologic disability from osmotic demyelination if treatment is excessive. Unfortunately, as is true of all electrolyte disturbances, there are no randomized trials to guide the treatment of this challenging disorder. Rather, therapeutic decisions rest on physiologic principles, animal models, observational studies, and single-patient reports. European guidelines and recommendations of an American Expert panel have come to similar conclusions on how much correction of hyponatremia is enough and how much is too much, but there are important differences. We review the evidence supporting these recommendations, identifying areas that rest on relatively solid ground and highlighting areas in greatest need of additional data.