Dysnatremias in Chronic Kidney Disease: Pathophysiology, Manifestations, and Treatment

Outcomes of Hospital-Acquired Hypernatremia

BACKGROUND

Hospital-acquired hypernatremia is highly prevalent, overlooked, and associated with unfavorable consequences. There are limited studies examining the outcomes and discharge dispositions of various levels of hospital-acquired hypernatremia in patients with or without CKD.

METHODS

We conducted an observational retrospective cohort study, and we analyzed the data of 1,728,141 patients extracted from the Cerner Health Facts database (January 1, 2000, to June 30, 2018). In this report, we investigated the association between hospital-acquired hypernatremia (serum sodium [Na] levels >145 mEq/L) and in-hospital mortality or discharge dispositions with kidney function status at admission using adjusted multinomial regression models.

RESULTS

Of all hospitalized patients, 6% developed hypernatremia after hospital admission. The incidence of in-hospital mortality was 12% and 1% in patients with hypernatremia and normonatremia, respectively. The risk of all outcomes was significantly greater for serum Na >145 mEq/L compared with the reference interval (serum Na, 135-145 mEq/L). In patients with hypernatremia, odds ratios (95% confidence interval) for in-hospital mortality, discharge to hospice, and discharge to nursing facilities were 14.04 (13.71 to 14.38), 4.35 (4.14 to 4.57), and 3.88 (3.82 to 3.94), respectively ( P < 0.001, for all). Patients with eGFR (Chronic Kidney Disease Epidemiology Collaboration) 60-89 ml/min per 1.73 m 2 and normonatremia had the lowest odds ratio for in-hospital mortality (1.60 [1.52 to 1.70]).

CONCLUSIONS

Hospital-acquired hypernatremia is associated with in-hospital mortality and discharge to hospice or to nursing facilities in all stages of CKD.

High Osmol Gap Hyponatremia Caused by Icodextrin: A Case Series Report

Recently, hyperosmolar hyponatremia following excessive off-label use of two exchanges of 2 L icodextrin daily during peritoneal dialysis (PD) was reported. We encountered a cluster of 3 cases of PD patients who developed hyperosmolar hyponatremia during on-label use of icodextrin. This appeared to be due to absorption of icodextrin since after stopping icodextrin, the serum sodium level and osmol gap returned to normal, while a rechallenge again resulted in hyperosmolar hyponatremia. We excluded higher than usual concentrations of specific fractions of dextrins in fresh icodextrin dialysis fluid (lot numbers of used batches were checked by manufacturer). We speculate that in our patients, either an exaggerated degradation of polysaccharide chains by α-amylase activity in dialysate, lymph, and interstitium and/or rapid hydrolysis of the absorbed larger degradation products in the circulation may have contributed to the hyperosmolality observed, with the concentration of oligosaccharides exceeding the capacity of intracellular enzymes (in particular maltase) to metabolize these products to glucose. Both hyponatremia and hyperosmolality are risk factors for poor outcomes in PD patients. Less conventional PD prescriptions such as off-label use of two exchanges of 2 L icodextrin might raise the risk of this threatening side effect. This brief report is intended to create awareness of a rare complication of on-label icodextrin use in a subset of PD patients and/or PD prescriptions.

Pseudohyponatremia: Mechanism, Diagnosis, Clinical Associations and Management

Pseudohyponatremia remains a problem for clinical laboratories. In this study, we analyzed the mechanisms, diagnosis, clinical consequences, and conditions associated with pseudohyponatremia, and future developments for its elimination. The two methods involved assess the serum sodium concentration ([Na]_S) using sodium ion-specific electrodes: (a) a direct ion-specific electrode (ISE), and (b) an indirect ISE. A direct ISE does not require dilution of a sample prior to its measurement, whereas an indirect ISE needs pre-measurement sample dilution. [Na]_S measurements using an indirect ISE are influenced by abnormal concentrations of serum proteins or lipids. Pseudohyponatremia occurs when the [Na]_S is measured with an indirect ISE and the serum solid content concentrations are elevated, resulting in reciprocal depressions in serum water and [Na]_S values. Pseudonormonatremia or pseudohypernatremia are encountered in hypoproteinemic patients who have a decreased plasma solids content. Three mechanisms are responsible for pseudohyponatremia: (a) a reduction in the [Na]_S due to lower serum water and sodium concentrations, the electrolyte exclusion effect; (b) an increase in the measured sample's water concentration post-dilution to a greater extent when compared to normal serum, lowering the [Na] in this sample; (c) when serum hyperviscosity reduces serum delivery to the device that apportions serum and diluent. Patients with pseudohyponatremia and a normal [Na]_S do not develop water movement across cell membranes and clinical manifestations of hypotonic hyponatremia. Pseudohyponatremia does not require treatment to address the [Na]_S, making any inadvertent correction treatment potentially detrimental.

Grafting of Crown Ether and Cryptand Macrocycles on Large Pore Stellate Mesoporous Silica for Sodium Cation Extraction

Regulation of the sodium cations level in the case of renal failure diseases is a very challenging task for clinicians, and new pollutant extractors based on nanomaterials are emerging as potential treatments. In this work, we report different strategies for the chemical functionalization of biocompatible large pore mesoporous silica, denoted stellate mesoporous silica (STMS), with chelating ligands able to selectively capture sodium. We address efficient methods to covalently graft highly chelating macrocycles onto STMS NPs such as crown ethers (CE) and cryptands (C221) through complementary carbodiimidation reactions. Regarding sodium capture in water, C221 cryptand-grafted STMS showed better capture efficiency than CE-STMS due to higher sodium atom chelation in the cryptand cage (Na⁺ coverage of 15.5% vs. 3.7%). The sodium selectivity was hence tested with C221 cryptand-grafted STMS in a multi-element aqueous solution (metallic cations with the same concentration) and in a solution mimicking peritoneal dialysis solution. Results obtained indicate that C221 cryptand-grafted STMS are relevant nanomaterials to extract sodium cations in such media and allow us to regulate their levels.

Hyponatremia Is an Overlooked Sign of Trouble Following Total Joint Arthroplasty

BACKGROUND

Hyponatremia is a common electrolyte abnormality in arthroplasty patients. This issue, underrecognized by surgeons, can impact the postoperative course of patients. There are, however, little data on the implications of sodium disturbances following total joint arthroplasty (TJA). The primary aims of this study were to (1) report the rate of hyponatremia following TJA, and (2) examine the impact of hyponatremia on the perioperative course of TJA patients.

METHODS

This was a retrospective analysis of 3,071 primary and revision TJAs performed between 2015 and 2017. Based on preoperative and postoperative sodium values (pre-post), patients were classified into 4 groups: normonatremic-normonatremic (Group 1), normonatremic-hyponatremic (Group 2), hyponatremic-normonatremic (Group 3), and hyponatremic-hyponatremic (Group 4). Primary end points were length of stay (LOS), postoperative discharge, in-hospital complications, and 90-day readmissions.

RESULTS

The distribution of cases was 84.6% Group 1, 9.4% Group 2, 2.1% Group 3, and 3.8% Group 4. Overall, 13.2% of patients had hyponatremia after TJA. Older age, hip arthroplasty, general anesthesia, higher Charlson Comorbidity Index, congestive heart failure, revision surgery, and history of stroke, liver disease, and chronic kidney disease were risk factors for postoperative hyponatremia. Patients with postoperative hyponatremia (Groups 2 and 4) had greater likelihoods of having a 90-day complication and non-home discharge and greater LOS.

CONCLUSIONS

Postoperative hyponatremia was a relatively common occurrence in patients undergoing TJA, and was associated with greater LOS, complications, and non-home discharge. Surgeons should identify patients at risk for developing sodium abnormalities in order to optimize these patients and avoid increased resource utilization.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Hypertonic Saline Infusion for Hyponatremia: Limitations of the Adrogué-Madias and Other Formulas

Hypertonic saline infusion is used to correct hyponatremia with severe symptoms. The selection of the volume of infused hypertonic saline ( VInf ) should address prevention of overcorrection or undercorrection. Several formulas computing this VInf have been proposed. The limitations common to these formulas consist of (1) failure to include potential determinants of change in serum sodium concentration ([ Na ]) including exchanges between osmotically active and inactive sodium compartments, changes in hydrogen binding of body water to hydrophilic compounds, and genetic influences and (2) inaccurate estimates of baseline body water entered in any formula and of gains or losses of water, sodium, and potassium during treatment entered in formulas that account for such gains or losses. In addition, computing VInf from the Adrogué-Madias formula by a calculation assuming a linear relation between VInf and increase in [ Na ] is a source of errors because the relation between these two variables was proven to be curvilinear. However, these errors were shown to be negligible by a comparison of estimates of VInf by the Adrogué-Madias formula and by a formula using the same determinants of the change in [ Na ] and the curvilinear relation between this change and VInf . Regardless of the method used to correct hyponatremia, monitoring [ Na ] and changes in external balances of water, sodium, and potassium during treatment remain imperative.

A Case Series of Uncommon Sodium Disorders in Common Clinical Scenarios

Dysnatremias or sodium disorders (either hyponatremia or hypernatremia) are the most common electrolyte problems in clinical medicine. They pose diagnostic and therapeutic challenges and have high mortality. Even mild changes in sodium levels from normal are associated with worse outcomes and considerable morbidity and mortality. We present a series of four patients with either hypo- or hypernatremia in different clinical scenarios requiring immediate treatment with close monitoring to avoid overcorrection. This case series shows that uncommon or unusual sodium disorders can happen in an otherwise usual situation.

Progression of chronic kidney disease among black patients attending a tertiary hospital in Johannesburg, South Africa

BACKGROUND

Chronic kidney disease (CKD) is a major public health issue worldwide and is an important contributor to the overall non-communicable disease burden. Chronic kidney disease is usually asymptomatic, and insidiously and silently progresses to advanced stages in resource limited settings.

METHODOLOGY

A prospective longitudinal study was carried out on black patients with CKD attending the kidney outpatient clinic at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in South Africa, between September 2019 to March 2022. Demographic and clinical data were extracted from the ongoing continuous clinic records, as well as measurements of vital signs and interviews at baseline and at follow up. Patients provided urine and blood samples for laboratory investigations as standard of care at study entry (0) and at 24 months, and were followed up prospectively for two (2) years. Data were descriptively and inferentially entered into REDcap and analysed using STATA version 17, and multivariable logistic regression analysis was used to identify predictors of CKD progression.

RESULTS

A total of 312 patients were enrolled into the study, 297 (95.2%) patients completed the study, 10 (3.2%) patients were lost to follow and 5 (1.6%) patients died during the study period. The prevalence of CKD progression was 49.5%, while that of CKD remission was 33% and CKD regression was 17.5%. For patients with CKD progression the median age at baseline was 58 (46-67) years, the median eGFR was 37 (32-51) mL/min/1.73 m2, median urine protein creatinine ratio (uPCR) was 0.038 (0.016-0.82) g/mmol and the median haemoglobin (Hb) was 13.1 (11.7-14.4) g/dl; 95.2% had hypertension, 40.1% patients had diabetes mellitus and 39.5% had both hypertension and diabetes mellitus. Almost half (48.3%) of patients with CKD progression had severely increased proteinuria and 45.6% had anaemia. Variables associated with higher odds for CKD progression after multivariable logistic regression analysis were severely increased proteinuria (OR 32.3, 95% CI 2.8-368.6, P = 0.005), moderately increased proteinuria (OR 23.3, 95% CI 2.6-230.1, P = 0.007), hypocalcaemia (OR 3.8, 95% CI 1.0-14.8, P = 0.047), hyponatraemia (OR 4.5, 95% CI 0.8-23.6, P = 0.042), anaemia (OR 2.1, 95% CI 1.0-4.3, P = 0.048), diabetes mellitus (OR 1.8, 95% CI 0.9-3.6, P = 0.047), elevated HbA1c (OR 1.8, 95% CI 1.2-2.8, P = 0.007) and current smoking (OR 2.8, 95% CI 0.9-8.6, P = 0.049).

CONCLUSION

Our study identified a higher prevalence of CKD progression in a prospective longitudinal study of black patients with CKD compared with literature reports. CKD Progression was associated with proteinuria, diabetes mellitus, elevated HbA1c, anaemia, hypocalcaemia, hyponatraemia and current smoking in a cohort of black patients with CKD who had controlled hypertension and diabetes mellitus at baseline.

Hyponatremia in peritoneal dialysis patients

Hyponatremia is the most common disorder of body fluid and electrolyte balance encountered in clinical practice, and also in peritoneal dialysis (PD) population. Depending on the severity and the speed of drop in sodium concentration, the symptoms can vary from asymptomatic hyponatremia to mild and non-specific symptoms or severe and life-threatening situations. Hyponatremia is associated with high morbidity and mortality. Its pathophysiology is complex, specifically in patients undergoing PD. The etiological workup can be cumbersome but is of paramount importance for early and appropriate treatment. In this article, we review the clinical manifestations as well as the pathophysiology and the specific etiologies of hyponatremia in peritoneal dialysis patients, and we propose a diagnostic algorithm.