Dysnatremia, vasopressin, atrial natriuretic peptide and mortality in patients with community-acquired pneumonia: results from the german competence network CAPNETZ.

BACKGROUND: Dysnatremia is a frequent finding in patients with community acquired pneumonia (CAP) and a predictor of mortality. We studied the relation between dysnatremia, comorbidities and CT-pro-AVP and MR-proANP. METHODS: We enrolled 2138 patients (60 ± 18 years, 55% male) with CAP from the CAPNETZ database. Pro-atrial natriuretic peptide (proANP), pro-vasopressin (proAVP), serum sodium and CRB-65 score were determined on admission. Patients were followed up for 28 days. Sodium concentration on admission was examined as a function of mortality at 28 days. Hyponatremia (HypoN) was defined as admission serum sodium <136 mmol/L, hypernatremia (HyperN) as admission serum sodium >145 mmol/L. RESULTS: HypoN was diagnosed in 680 (31.8%) patients, HyperN in 29 (1.4%) patients. Comorbidities were associated with sodium levels, and CT-pro-AVP and MR-proANP were inversely related to sodium levels. Patients with HypoN were older, had a higher CRB-65 score and higher values of CT-proAVP and MR-proANP (all p < 0.05). When examined as a function of sodium values, a U-shaped association was found between sodium levels and 28 day mortality. In multivariate Cox proportional hazards analysis, HypoN and HyperN were independent predictors of 28 day mortality. Sodium levels added to the predictive potential of proAVP and proANP. CONCLUSION: HypoN is common at admission among CAP patients and is independently associated with mortality. HyperN is rare at admission among CAP patients but is also independently associated with mortality. The combination of sodium and CT-pro-AVP and MR-proANP levels achieved the highest prediction of mortality.

Hypernatremia in the elderly: relation to infection and mortality.

The records of 23 elderly patients admitted to a county hospital with dehydration and hypernatremia were reviewed. One of these patients had the highest serum sodium level (202 mEq/L) reported in an adult. The overall mortality of 48 percent was not related to the degree of hypernatremia. However, two-thirds of the 17 patients with acute bacteria infections died, whereas all 5 noninfected patients survived. Infection was not always apparent at the time of admission to the hospital. It is proposed that early and appropriate antibiotic therapy may reduce the high mortality associated with hypernatremia in the elderly.