IGFBP4 and lobular neoplasia: Although serum IGFBP-4 levels correlated poorly with severity of proteinuria, as indicated by urinary protein:creatinine ratio (R = 0.047, P > 0.6, Fig 2A), they correlated positively with serum creatinine levels (R = 0.612, P < 0.0001, Fig 2B), and inversely with eGFR, as calculated using the MDRD Study equation (R = -0.609, P < 0.0001, Fig 2C), in patients with LN.