Reference change values and determinants of variability of NT-proANP and GDF15 in stable chronic heart failure.

Biovariability, reference change values (RCV), and index of individuality (IOI) have not been previously described for NT-proANP or GDF15. Also, the relation of changes of these markers to other clinical variables or biomarkers is unknown. In 41 patients with stable chronic systolic dysfunction, NT-proANP and GDF15 were measured alongside with clinical variables/markers comprising NT-proBNP, hsTnT, and hsCRP at four sampling intervals (2 weeks, 1-, 2-, 3-month intervals). At 2 weeks, 1-, 2-, and 3-month-follow-up, individual NT-proANP variations were 27.1, 22.5, 28.9, 15.6%, respectively, corresponding to RCVs of 53.2, 62.4, 80.2, and 43.2%, respectively. For GDF15, the respective individual variations were 6.8, 4.1, 5.5, 6.8%, corresponding to RCVs of 18.8, 11.5, 15.3 and 18.8%. Neither changes of NT-proANP or GDF15 correlated with changes in any of the clinical variables or biomarkers examined except for GDF15 with renal function. Baseline hormonal levels and clinical variables did not consistently influence the extent of change. The IOI was 0.19-0.35 according to interval for NT-proANP and 0.06-0.09 for GDF 15. In patients with CHF preselected for clinical stability changes of NT-proANP at intermediate follow-up do not correlate with changes in other variables; changes of GDF15 inversely correlate with renal function. The extent of change in both markers is not related to baseline hormonal levels or other baseline variables. RCVs are high for NT-proANP and low for GDF15, while inter-individual variation is high in GDF15 and intermediate in NT-proANP.