Are plasma concentrations of N- and C-terminal ANP stable at room temperature for up to 72 hours?
N-terminal ANP is stable at room temperature for up to 72 hours, making it potentially practical for routine clinical diagnosis of heart failure, unlike C-terminal ANP.
BACKGROUND: Plasma concentrations of atrial natriuretic peptide (ANP) are increased in patients with ventricular dysfunction and could have a diagnostic role in heart failure. ANP may be unstable after collection, however, limiting any practical diagnostic role. METHODS: Blood samples were obtained from 18 patients with various conditions. Aliquots were either processed optimally or kept as blood or plasma at room temperature for 6-72 h before processing. RESULTS: Concentrations of C-terminal ANP were lower in specimens kept as blood for 24 and 72 h (mean difference from control -43% and -76%, respectively, (P < 0.001) but N-terminal ANP (extracted) seemed to be stable under all conditions studied (-2% at 24 h and -7% at 72 h, not significant). CONCLUSIONS: N-terminal ANP (extracted) is stable and potentially has a role in the diagnosis of heart failure in routine clinical practice.
Cleland et al. (Mon,) studied this question.