Hyponatremia: how much attention do we pay to it?

The objective is to describe hyponatremia in patients hospitalized in geriatric (GU) and Internal medicine units (IM), its characteristics and diagnostic approach in order to improve its management and treatment. It is a retrospective study. We collected data through the informatic system of the hospital, performing statistical analysis with SmallStata14. We analyzed patients admitted during 2015 who showed hyponatremia at admission or developed it in any moment during hospitalization. On 824 patients admitted to the Geriatric (n=351) and Internal Medicine (n=473) wards during 2015 (mean age 77.5±14.6 yrs; 56% males), 140 patients (17%) had hyponatremia. Hyponatremia was already present at admission in the emergency unit in 49 patients (74% mild; 14% moderate and 12% severe); 10 patients had hypernatremia but developed hyponatremia thereafter. More than half of the patients was taking at least one drug or had a comorbidity possibly causing hyponatremia. 78 patients (56%) developed it during hospitalization (82% mild, 17% moderate and 1% severe). The mean sodium nadir during hospitalization was 131.8±2.4mEq/l. Further analyses to improve the diagnostic accuracy were performed in a minority of cases (plasmatic osmolarity has never been measured, urinary osmolarity and sodium in only 3 and 14 patients respectively). At hospital discharge 48 (34%) patients were still hyponatremic (in 79% mildly) and 71 patients were still assuming at least one drug possibly causing hyponatremia. The hyponatremia was often neglected in the letter of discharge. Hyponatremia is a common observation in GU and IM and it can be due to several causes thus guidelines for its treatment are often useless. The lack of appropriate investigations often lead to improper management. Since even mild hyponatremia has been associated with bad clinical outcomes, more attention should be given, in order to improve the management. Further studies are ongoing.