Plasma levels of IGF-I, IGFBP-3, IGFBP-1, and insulin in normal individuals and patients with PV (pooled data from two experiments). Values for IGF-I are given in micrograms per liter (n = 41 for normal and n = 23 for PV), IGFBP-3 in milligrams per liter × 10−2 (n = 41 for normal and n = 23 for PV), IGFBP-I in micrograms per liter × 10−1 (n = 41 for normal and n = 23 for PV), (IGFBP-1) in micrograms per liter × 10−1 (n = 38 for normal and n = 23 for PV), and insulin in picomoles per liter (n = 40 for normal and n = 23 for PV) for normal individuals (□) and patients with PV (▪). The level of plasma IGFBP-1 in PV is significantly higher than that in normal individuals (*P < .01; **P < .001). However, the circulating levels of IGF-I, IGFBP-3, and insulin are not significantly different in PV versus normal. Three values for IGFBP-1 greater than 104 μg/L in the normal (N) of experiment 1 (Fig 1) were statistically shown to lie outside the confidence limits of both the normal (P < .001) and the PV (P < .01) populations sampled. The mean ± standard error of the mean for the level of IGFBP-1 in normals, if these values were to be excluded, is given in brackets.
