CALCA and acquired polycythemia vera: Serum PCT levels (at the first visit) were increased in patients with GPP than in patients with PV (Figure 1); the mean serum PCT levels in patients with PV, PsA, and GPP were 0.01 ng/mL (25th–75th percentile; 0.00–0.03), 0.013 ng/mL (0.00–0.03), and 0.12 ng/mL (0.05–0.18), respectively.