• Differential diagnosis of hyponatraemia.

      Thompson, Chris; Berl, Tomas; Tejedor, Alberto; Johannsson, Gudmundur; Academic Department of Endocrinology, Beaumont Hospital and RCSI Medical School, Beaumont Road, Dublin 9, Ireland. christhompson@beaumont.ie (2012-03)
      The appropriate management of hyponatraemia is reliant on the accurate identification of the underlying cause of the hyponatraemia. In the light of evidence which has shown that the use of a clinical algorithm appears to improve accuracy in the differential diagnosis of hyponatraemia, the European Hyponatraemia Network considered the use of two algorithms. One was developed from a nephrologist's view of hyponatraemia, while the other reflected the approach of an endocrinologist. Both of these algorithms concurred on the importance of assessing effective blood volume status and the measurement of urine sodium concentration in the diagnostic process. To demonstrate the importance of accurate diagnosis to the correct treatment of hyponatraemia, special consideration was given to hyponatraemia in neurosurgical patients. The differentiation between the syndrome of inappropriate antidiuretic hormone secretion (SIADH), acute adrenocorticotropic hormone (ACTH) deficiency, fluid overload and cerebral salt-wasting syndrome was discussed. In patients with SIADH, fluid restriction has been the mainstay of treatment despite the absence of an evidence base for its use. An approach to using fluid restriction to raise serum tonicity in patients with SIADH and to identify patients who are likely to be recalcitrant to fluid restriction was also suggested.
    • Hyponatraemia: an overview of frequency, clinical presentation and complications.

      Thompson, Chris; Hoorn, Ewout J; Academic Department of Endocrinology, Beaumont Hospital and RCSI Medical School, Beaumont Road, Dublin 9, Ireland. christhompson@beaumont.ie (2012-03)
      Hyponatraemia (defined as a serum sodium concentration <136 mmol/L) is the most frequently encountered electrolyte disturbance in clinical practice. It is classified according to volume status (hypovolaemia, hypervolaemia or euvolaemia), reflecting the relative proportions of water and sodium within the body. The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is the most common cause of euvolaemic hyponatraemia. Although hyponatraemia is associated with poor prognosis and increased length of hospital stay, it is often poorly managed and sometimes underdiagnosed and undertreated. This article provides an overview of the frequency, pathophysiology and complications associated with this common clinical condition.