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.

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Clinical practice guideline on diagnosis and treatment of hyponatraemia

http://www.svemonline.org/wp-content/uploads/2016/02/endotips-vol-03-2.pdf

Diagnosis, Evaluation, and Treatment of Hyponatremia: Expert Panel Recommendations

This review considers the causes and consequences of an abnormal plasma sodium concentration and offers a framework for correcting it.

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Disorders of Plasma Sodium — Causes, Consequences, and Correction

Background
Hyponatremia is a common electrolyte disorder. Multiple organizations have published guidance documents to assist clinicians in managing hyponatremia. We aimed to explore the scope, content, and consistency of these documents.

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Diagnosis and treatment of hyponatremia: a systematic review of clinical practice guidelines and consensus statements

Acute kidney injury (AKI) is common and is associated with serious short- and long-term complications. Early diagnosis and identification of the underlying aetiology are essential to guide management. In this review, we outline the current definition of AKI and the potential pitfalls, and summarise the existing and future tools to investigate AKI in critically ill patients.

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Acute kidney injury 2016: diagnosis and diagnostic workup

Background: Treatment of patients with hyponatremia varies widely; thus, convenient diagnostic parameters are needed to guide the correct treatment strategy. This study was designed to evaluate the diagnostic potential of copeptin, the C-terminal part of provasopressin, as a new marker in the differential diagnosis of hyponatremia. Methods: In this prospective observational study, 106 consecutive hyponatremic patients were classified based on their history, clinical evaluation, and laboratory tests. In patients and 32 healthy control subjects, plasma copeptin concentration and standard biochemical parameters were tested for their utility of diagnosing the syndrome of inappropriate antidiuresis (SIAD). Results: Four patients (4%) were diagnosed as primary polydipsia, nine (8%) as diuretic-induced hyponatremia, 42 (40%) as SIAD, 29 (27%) as hypovolemic hyponatremia, and 22 patients (21%) as hypervolemic hyponatremia. In controls, a close correlation between plasma copeptin and serum sodium (r2 = 0.62, P < 0...

/pdf/copeptin-in-the-differential-diagnosis-of-hyponatremia-6dm7lfe4li.pdf

Copeptin in the Differential Diagnosis of Hyponatremia

Background: The syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hyponatremia. Its diagnosis requires decreased serum osmolality, inappropriately diluted urine (e.g. >100 mOsm/kg), clinical euvolemia, and a urinary sodium (Na) excretion (U-Na) more than 30 mmol/liter. However, in hyponatremic patients taking diuretics, this definition is unreliable due to the natriuretic effect of diuretics. Here, we examined the diagnostic potential of alternative laboratory measurements to diagnose SIAD, regardless of the use of diuretics. Methods: A total of 86 consecutive hyponatremic patients (serum Na <130 mmol/liter) was classified based on their history, clinical evaluation, osmolality, and saline response to isotonic saline into a SIAD and a non-SIAD group. U-Na, serum urate concentration, and fractional excretion (FE) of Na, urea, and uric acid (UA) were measured in all subjects. The accuracy to diagnose SIAD was assessed using receiver operating characteristic analysis. Results: A tot...

/pdf/value-of-fractional-uric-acid-excretion-in-differential-4vkzqhmqe4.pdf

Value of Fractional Uric Acid Excretion in Differential Diagnosis of Hyponatremic Patients on Diuretics

https://www.amjmed.com/article/S0002-9343(10)00104-X/pdf

Utility and Limitations of the Traditional Diagnostic Approach to Hyponatremia: A Diagnostic Study

BACKGROUND
The differential diagnosis of hyponatremia is often challenging because of its association with multiple underlying pathophysiological mechanisms, diseases, and treatment options. Several algorithms are available to guide the diagnostic approach to hyponatremia, but their diagnostic and clinical utility has never been evaluated. We aimed to assess in detail the diagnostic utility as well as the limitations of the existing approaches to hyponatremia.


METHODS
Each of the 121 consecutive subjects presenting with hyponatremia (serum sodium <130 mmoL/L) underwent 3 different and independent diagnostic and therapeutic approaches: inexperienced doctor applying an established Algorithm, intensive care senior physicians acting as Senior Physician, and senior endocrinologist serving as Reference Standard.


RESULTS
The overall diagnostic agreement between Algorithm and Reference Standard was 71% (respective Cohen's kappa and delta values were 0.64 and 0.70), the overall diagnostic agreement between Senior Physician and Reference Standard was 32% (0.20 and 0.19, respectively). Regarding the therapeutic consequences, the diagnostic accuracy of the Algorithm was 86% (0.70 and 0.72, respectively) and of the Senior Physician was 48% (0.01 and 0.04, respectively). In retrospect, by disregarding the patient's extracellular fluid volume and assessing the effective arterial blood volume by determination of the fractional urate excretion, the Algorithm improved its diagnostic accuracy to 95%.


CONCLUSION
Although the Algorithm performed reasonably well, several shortcomings became apparent, rendering it difficult to apply the Algorithm without reservation. Whether some modifications may enhance its diagnostic accuracy and simplify the management of hyponatremia needs to be determined.

Anne Blechschmidt

Papers

Copeptin in the Differential Diagnosis of Hyponatremia

Value of Fractional Uric Acid Excretion in Differential Diagnosis of Hyponatremic Patients on Diuretics

Utility and Limitations of the Traditional Diagnostic Approach to Hyponatremia: A Diagnostic Study

Utility and limitations of the traditional diagnostic approach to hyponatremia: a diagnostic study

Copeptin in the differential diagnosis of hyponatremia