IGF1 and acromegaly: Accordingly, the Acromegaly Consensus Group recently revisited the guidelines on criteria for disease control as defined in Cortina in 2000 and recommended a regular retesting in patients with normal age-adjusted IGF-I levels and postglucose GH nadir levels after OGTT ≥ 0.4 mcg/L, obtained using assays that contain standards calibrated against the WHO 2nd International Standard (IS) 98/574, with antibodies which essentially recognize the 22 kDa isoform and with results expressed as mass unit (μg/L) [8–10].