title: Reference range and short- and long-term biological variation of interleukin (IL)-6, IL-17A and tissue necrosis factor-alpha using high sensitivity assays.
abstract: Interleukin (IL)-6, and tissue necrosis factor alpha (TNF-α) are established biomarkers for clinical practice and use in clinical trials of patients with cardiovascular disease. IL-17A may be an emerging marker for atherosclerosis disease progression. We measured IL-6, TNF-α, and IL-17A using a high sensitivity immunoassay (Erenna, Singulex, Inc.) to determine the reference range and to calculate the weekly (25 subjects over 6weeks) and monthly (17 subjects over 9months) biological variation (BV) from apparently healthy subjects and those attending a cardiovascular disease clinic. As a validation for the experimental and statistical approach taken, the weekly BV for high sensitivity C-reactive protein was also determined and result compared to previous reports. The upper 95th percentile reference limit for IL-6, TNF-α, and IL17-A was 4.45, 2.53, and 1.93pg/mL, respectively. The intra-individual variability ranged from 21% to 57% and the inter-individual variation ranged from 22% to 53%. The corresponding index of individuality was 0.65-1.6 and reference change values from 63% to 161%. The BV for IL-6 and TNF-α are similar to previous reports, documenting their diagnostic utility in clinical practice. Up until now, the biological variation of IL-17A and upper reference limit has not been previously reported, thereby limiting the use of this marker in clinical trials.
authors.affiliation: Singulex Inc., Alameda, CA, United States.
authors.forename: John
authors.initials: J
authors.lastname: Todd
authors.forename: Peter
authors.initials: P
authors.lastname: Simpson
authors.forename: Joel
authors.initials: J
authors.lastname: Estis
authors.forename: Victoria
authors.initials: V
authors.lastname: Torres
authors.forename: Alan H B
authors.initials: AH
authors.lastname: Wub
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D020381:Interleukin-17 / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D020381:Interleukin-17; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein
keywords: Biological variability; CLIA; CV(A), CV(I), CV(G); Clinical Laboratory Improvement Amendments; EDTA; HF; ICC; IL; Interleukin; LDT; LLoQ; NYHA; New York Heart Association; TNF-α; Tissue necrosis factor; analytical, intra-assay and inter-assay coefficient of variance, respectively, LoD, limit of detection; ethylenediaminetetraacetic acid; heart failure; high-sensitivity C-reactive protein; hs-CRP; interleukin; intra-class correlation coefficient; lab developed test; lower limit of quantitation; tissue necrosis factor, CVD, cardiovascular disease