Understanding dysnatremia

Abstract

Dysnatremia—either hyponatremia or hypernatremia—is frequently encountered in the clinical practice and often poses a diagnostic and therapeutic challenge for physicians. Despite their frequent occurrence, disorders of the water and sodium balance in the human body have puzzled many physicians over the years and often remain elusive for those lacking experience in their interpretation and management. In this article, we derive a transparent governing equation that can be used by clinicians to describe how a change in relevant physiological parameters will affect the plasma sodium concentration. As opposed to many existing models, our model takes both input and output into account, and integrates osmolarity and tonicity. Our governing equation should be considered a means for clinicians to get a better qualitative understanding of the relationship between the plasma sodium concentration and the variables that influence it for a wide range of scenarios.

COVID-19 and dysnatremia: A comparison between COVID-19 and non-COVID-19 respiratory illness

“… 10 The much more accurate electrolyte-free water clearance (which is positive in these patients due to the relatively low concentration of electrolytes in their urine) easily explains the development of hypernatremia. 10 , 11 As presented in the results, the plasma sodium concentration can reach alarming heights. Future studies should focus on the balance between dehydration prevention during ICU admission and avoiding pulmonary edema in COVID-19.…”

“…As the urine osmolality in none of the hyponatremic COVID-19 patients dropped below 274 mOsmol/L, other factors, such as 'tea and toast syndrome', seem less relevant in COVID-19associated hyponatremia, even though the nutritional status of these patients is often questionable at best. 11 A limitation of our study is that-while the occurrence of dysnatremia during admission could be reliably established in our patient groups-our data often did not allow the analysis of a temporal relationship between the onset of dysnatremia and the clinical course of COVID-19, which would have been desirable for proving causality. Furthermore, due to a large number of confounders, such as-but certainly not limited to-patient age, smoking status, and co-morbidity, the possible causality of dysnatremia in COVID-19-related deaths could not be reliably established in our retrospective cohort of COVID-19 patients.…”

“… 13 , 14 As pulmonary disease is a fairly common cause of SIADH, this seems pathophysiologically plausible. 11 This being said, hypovolemia-mediated ADH release could also have played an etiological role in a minority of cases in which the urine sodium excretion was strongly reduced (<15 mmol/L), especially because many physicians have been reluctant to initiate intravenous fluid therapy in these patients due to the fear of pulmonary edema. As the urine osmolality in none of the hyponatremic COVID-19 patients dropped below 274 mOsmol/L, other factors, such as ‘tea and toast syndrome’, seem less relevant in COVID-19-associated hyponatremia, even though the nutritional status of these patients is often questionable at best.…”

“…As the urine osmolality in none of the hyponatremic COVID-19 patients dropped below 274 mOsmol/L, other factors, such as ‘tea and toast syndrome’, seem less relevant in COVID-19-associated hyponatremia, even though the nutritional status of these patients is often questionable at best. 11 …”

An Overview on Sodium Imbalance from an Emergency Physician Perspective

“…These receptors sense the change in plasma tonicity and affect water intake and excretion by inducing thirst and the release of anti-diuretic hormone (ADH), respectively [5]. ADH is a particularly powerful tool because it allows the kidneys to reabsorb more water from the collecting tubules leading to a net loss of sodium more than water, thereby regulating the water and sodium balance in the bloodstream [3,6].…”