Prognostic and diagnotsic biomarkers linked to water and sodium regulation in acute dyspnea

Biomarkers related to water and sodium regulation, such as B-type natriuretic peptides (BNPs), provide clinically useful information with regards to prognosis and diagnosis, especially in patients with heart failure (HF). Chronic obstructive pulmonary disease (COPD), currently the third most common cause of death globally, is also associated with changes in water and sodium regulation, but the value of these biomarkers in the COPD setting is uncertain. The aim of this thesis was to determine the prognostic and diagnostic value of hyponatremia and two novel biomarkers, specifically copeptin and mid-regional-proANP (MR-proANP), in patients admitted to hospital with acute dyspnea. Sodium and biomarker concentrations were measured on admission, and the cause of dyspnea was diagnosed by an adjudication committee. Survival was recorded after a median follow-up of 2.2 years, and the association between biomarkers and mortality was assessed. Subgroup analysis was performed in patients with acute HF and acute exacerbation of COPD (AECOPD). Hyponatremia was prevalent in acute dyspnea regardless of whether the cause of dyspnea was acute HF or AECOPD. Hyponatremia was associated with increased mortality in acute HF but not in AECOPD. Copeptin and MR-proANP, on the other hand, were independently associated with mortality in both acute HF and AECOPD. The prognostic accuracy of copeptin and MR-proANP were comparable to the amino terminal fragment of BNP (NT-proBNP) in acute HF and superior to NT-proBNP in AECOPD. Concerning diagnostic properties, copeptin and MR-proANP concentrations were increased in acute HF compared to other causes of dyspnea, but only MR-proANP matched the diagnostic accuracy of NT-proBNP. Thus, copeptin and MR-proANP shows great potential, especially as prognostic biomarkers in acute HF and AECOPD.