Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association – European Dialysis and Transplant Association (ERA–EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.
Goce Spasovski, Raymond Vanholder, Bruno Allolio, Djillali Annane, Steve Ball, Daniel Bichet, Guy Decaux, Wiebke Fenske, Ewout J Hoorn, Carole Ichai, Michael Joannidis, Alain Soupart, Robert Zietse, Maria Haller, Sabine van der Veer, Wim Van Biesen, and Evi Nagler
Julie Refardt, Clara Odilia Sailer, Irina Chifu, Bettina Winzeler, Ingeborg Schnyder, Martin Fassnacht, Wiebke Fenske, Mirjam Christ-Crain, and the CODDI-Investigators
Diagnosis and treatment of dysnatremia is challenging and further complicated by the pitfalls of different sodium measurement methods. Routinely used sodium measurements are the indirect (plasma/serum) and direct (whole blood) ion-selective electrode (ISE) method, showing discrepant results especially in the setting of acute illness. Few clinicians are aware of the differences between the methods in clinically stable patients or healthy volunteers.
Data of 140 patients and 91 healthy volunteers undergoing osmotic stimulation with hypertonic saline infusion were analyzed. Sodium levels were measured simultaneously by indirect and direct ISE method before and at different time points during osmotic stimulation up to a sodium threshold of ≥150 mmol/L. The primary outcome was the difference in sodium levels between the indirect and direct ISE method.
878 sodium measurements were analyzed. Mean (s.d.) sodium levels ranged from 141 mmol/L (2.9) to 151 mmol/L (2.1) by the indirect ISE compared to 140 mmol/L (3) to 149 mmol/L (2.8) by the direct ISE method. The interclass correlation coefficient between the two methods was 0.844 (95% CI: 0.823–0.863). On average, measurements by the indirect ISE were 1.9 mmol/L (95% CI limits: −3.2 to 6.9) higher than those by the direct ISE method (P < 0.001). The tendency of the indirect ISE method resulting in higher levels increased with increasing sodium levels.
Intra-individual sodium levels differ significantly between the indirect and direct ISE method also in the absence of acute illness. It is therefore crucial to adhere to the same method in critical situations to avoid false decisions due to measurement differences.
Charlotte Michaela Fries, Yoon Ju Bae, Nada Rayes, Benjamin Sandner, Berend Isermann, Michael Stumvoll, Valentina Fagotto, Martin Reincke, Martin Bidlingmaier, Vogel Mandy, Jürgen Kratzsch, and Wiebke Kristin Fenske
Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) has become state of the art for the quantitative analysis of steroid hormones. Although method comparisons show that aldosterone measurement using LC-MS/MS yields considerably lower levels than immunoassays (IAs), method-specific cutoff values for primary aldosteronism (PA) are largely missing. Objective of this study was to analyze the diagnostic accuracy of proposed LC-MS/MS-specific cutoff values for the saline infusion test (SIT).
Design and methods
From 2016 to 2019, 104 consecutive patients suspected of PA underwent the SIT and captopril challenge test in the tertiary medical center at the University Hospital of Leipzig, Germany. Patients with positive case confirmation underwent adrenal imaging and adrenal venous sampling for subtype classification.
Overall, proposed assay-specific PACLC-MS/MS cutoff values for the SIT achieved higher diagnostic accuracy than established PACIA values with a sensitivity and specificity of 87.5% (95% CI: 71.0–96.5) and 97% (95% CI: 89.6–99.6) for a cutoff of 120 pmol/L and 93.8% (95% CI: 79.2–99.2) and 92.5% (95% CI: 83.4–97.5) for a cutoff of 94 pmol/L. The most accurate post-SIT PACLC-MS/MS cutoff value in this study was 83 pmol/L, yielding a sensitivity and specificity of 96.9% (95% CI: 83.8–99.9) and 92.5% (95% CI: 83.4–97.5), respectively.
The present data confirm the need for the implication of lower method-specific aldosterone cutoff values for the diagnosis of PA with LC-MS/MS based aldosterone measurement.