Comparison of sample types for N-terminal pro-B-type natriuretic peptide measured on the Siemens Immulite 2500 and Dimension Vista LOCI methods.
BACKGROUND
Measurement of serum natriuretic peptides is recommended in patients with suspected heart failure. Assays for N-terminal pro-B-type natriuretic peptide (NT-proBNP) are available on several platforms and can be measured in serum or heparinized plasma. Siemens Healthcare Diagnostics do not recommend the use of serum for the Immulite NT-proBNP assay. Serum offers some practical advantages over plasma. We investigated the suitability of serum for use with the Immulite and Dimension Vista LOCI methods.


METHODS
Paired serum and heparinized plasma samples were drawn from patients in the Cardiology Department over a 48-h period. Samples spanning the NT-proBNP concentration range 50-60,000 ng/L were analysed using the Siemens Immulite 2500 and Dimension Vista LOCI methods.


RESULTS
There was no significant difference between serum NT-proBNP concentrations on either platform (P = 0.0665). Plasma NT-proBNP measured using the Immulite were moderately higher than on Vista (P < 0.0001). There was a small but statistically significant difference between plasma and serum NT-proBNP measured using the Immulite (P = 0.0002) with plasma values higher than serum. A similar comparison between plasma and serum NT-proBNP measured using the Vista showed no difference (P = 0.3662).


CONCLUSIONS
We have demonstrated the suitability of serum for use on the Immulite 2500. Bland-Altman comparative analysis indicated minimal bias between both serum methods near the clinical cut-off level below which heart failure is considered unlikely (400 ng/L) up to the highest concentration tested (60,000 ng/L).
Department of Clinical Biochemistry, Aberdeen Royal Infirmary, Aberdeen AB25 2ZD, UK. r_peake@hotmail.co.uk
Roy W A
RW
Peake
Helen E
HE
Turner
Wendy
W
Leaper
Kevin A
KA
Deans
Andrew
A
Hannah
Bernard L
BL
Croal
D019963:Clinical Chemistry Tests / Q000295:instrumentation* / Q000592:standards; D006801:Humans; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D015203:Reproducibility of Results
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain