Aims: To evaluate the assessment and management of severe hyponatraemia in a large teaching hospital. Methods: Inpatients with serum sodium ,125 mmol/l were identified prospectively from a laboratory database over a six month period. Notes were examined and data extracted. Case notes were carefully reviewed retrospectively by a consultant endocrinologist with regard to accuracy of the diagnosis and the appropriateness of investigations and management. Results: 104 patients with a serum sodium ,125 mmol/l were identified. Mean (SD) age was 69 (14), 52% were female, mean hospital stay was 16 (12) days, and overall mortality 27%. Adequate investigations were rarely performed. Only 28 (26%) had plasma osmolality measured, 29 (27%) urine osmolality, 11 (10%) urinary sodium, 8 (8%) plasma cortisol, and 2 (2%) a short Synacthen test. Comparing the ''ward'' and ''specialist review'' diagnoses, there were significant discrepancies for ''no cause found'' (49% v 27%, p,0.001), alcohol (6% v 11% p,0.01), and syndrome of inappropriate antidiuresis (20% v 32%, p = 0.001). Treatment was often illogical with significant management errors in 33%. These included fluid restriction and intravenous saline given together (4%) and fluid restriction in diuretic induced hyponatraemia (6%). Mortality was higher in the group with management errors (41% v 20% p = 0.002). Conclusion: Severe hyponatraemia is a serious condition, but its investigation and evaluation is often inadequate. Some treatment patterns seem to be arbitrary and illogical, and are associated with higher mortality.H yponatraemia is the most common electrolyte disturbance encountered in clinical practice, with a prevalence up to 15% in a general hospital population.1 2 It is associated with considerable morbidity and mortality, but with differing views on optimal management.3 The evaluation of hyponatraemia can be challenging. Clinical judgment and laboratory investigations are important to help elucidate a diagnosis. Two recent studies have looked specifically at the investigation and management of hyponatraemia in a hospital setting.4 5 Both studies examined populations with severe hyponatraemia (plasma sodium (120 mmol/l) and concluded that investigations were often inadequate. Both reports however, involved small numbers of patients (47 and 42 patients respectively). In a separate report, Hochman et al looked at a population with less severe hyponatraemia (plasma sodium (130 mmol/l) and commented on aetiology, treatment, and prognosis. They found a high mortality rate (30%) and concluded that this was secondary to the underlying medical condition, rather than the degree of hyponatraemia or the subsequent treatment. 6 None of these studies addressed the accuracy of the diagnoses reached, or whether management was clinically appropriate. Also, the question of whether inappropriate management of hyponatraemia is correlated with adverse outcome, has not been reported.We have therefore studied a large cohort of patients to assess the accuracy of diagnosis and appropriatene...
