Radioimmunoassay for plasma C-type natriuretic peptide determination: a methodological evaluation.
C-Type natriuretic peptide (CNP) is a member of the family of natriuretic peptides with vasodilatory properties, and is produced and secreted by endothelial cells. It seems to play a central role in the paracrine vasomotor control of tone and to be important in several clinical conditions characterized by endothelial dysfunction. We evaluated the analytical performance of a commercially available radioimmunoassay for CNP after a preliminary extraction with Sep-Pak C18. Its analytical reliability was checked by determination of CNP plasma levels in healthy subjects (n = 23) and in patients with different diseases, likely characterized by endothelial dysfunction, such as chronic heart failure (n = 133) and cirrhosis (n = 84). The extraction yield was 78+/-3%. Accuracy of the radiommunological determination was evaluated by dilution (45-370 microL of extracted plasma) and recovery tests (>80%). Between- and within-assay variabilities were < or = 10% and analytical sensitivity was 0.41+/-0.015 pg/tube. Plasma CNP in patients with chronic heart failure and with cirrhosis was significantly raised compared to controls (p<0.0001 and p = 0.001, respectively). The sensitivity, accuracy and variability levels of the method proposed for CNP assay was suitable for reliable detection of changes in CNP plasma levels in the clinical setting.
Del Ry
Silvia
S
CNR Institute of Clinical Physiology, Pisa, Italy.
Maltinti
Maristella
M
Emdin
Michele
M
Passino
Claudio
C
Catapano
Giosué
G
Giannessi
Daniela
D
D000368:Aged; D003429:Cross Reactions; D005260:Female; D005355:Fibrosis / Q000097:blood; D006333:Heart Failure / Q000097:blood; D006801:Humans; D008297:Male; D008722:Methods; D008875:Middle Aged; D020098:Natriuretic Peptide, C-Type / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013045:Species Specificity
D020098:Natriuretic Peptide, C-Type