IGF 1 test is interrelated to GH disorders. In case any discrepancy in the IGF 1 level is detected in the test, you should follow it up with further IGF 1 tests to observe how the treatment is going. Apart from that, you need to consider the following tests to diagnose GH disorders.
GH Suppression Test
GH Stimulation Test
IGBP 3 Test (IGBP is the protein carrier of IGF 1 hormone).