 The study population will include 1 subjects with pituitary disease undergoing testing for GH deficiency GHRH arginine stimulation test, 2 subjects with suspicion of acromegaly undergoing the oral glucose tolerance test oGTT, and 3 normal controls undergoing both the GHRH Arginine test and the oGTT. Patients from all groups will have their blood drawn for the measurement of IGF-1. The serum from each test will be aliquoted and sent to the designated labs. 