Establishment of reference intervals for soluble ST2 from a United States population.

BACKGROUND

Soluble ST2 (sST2) is a protein in the interleukin-1 receptor family secreted by myocytes in response to mechanical strain. Elevated sST2 is strongly prognostic in patients with heart failure.

METHODS

sST2 was measured using the Presage ST2 ELISA. Evaluation included imprecision, linearity, recovery, analytical sensitivity, limit of quantification, stability, and sample type comparisons. Gender-specific reference intervals were established from 245 male and 245 female serum specimens.

RESULTS

At sST2 concentrations of 11.6, 26.9, and 88.0 ng/mL, the within-day CV was 7.6, 2.4, and 3.8%, respectively and the total CV was 11.5, 14.0, and 6.3%, respectively. The assay was linear over a concentration range of 2.8-161.1 ng/mL (y=0.95x+2.25; R(2)=0.997; Sy.x=3.03). The limit of quantification was 3.3 ng/mL. sST2 was stable for 2 days at room temperature, 10days at 4 °C, and 30 days at -20 °C. Concentrations of sST2 were significantly higher in males compared to females (24.9 vs. 16.9 ng/mL; p<0.0001) but were not correlated by age in either gender (r=-0.07; p=0.14). Reference intervals for sST2 were determined to be 8.6-49.3 and 7.2-33.5 ng/mL for males and females, respectively.

CONCLUSION

The Presage ST2 ELISA had acceptable performance characteristics for quantifying sST2 in serum or plasma. The assay is precise and linear over a wide sST2 concentration range and can measure low sST2 concentrations. Concentrations of sST2 are unaffected by age but are higher in males compared to females.