Please note on page FOUR of the article, (93) of the journal, (FIGURE TWO) the changes in IGF based on GH dosing. Although their is a linear relationship, the differences among the quantity of GH used by each sub-group are very difficult to extrapolate into an exacting dose.
That is, far to much overlap exists between the quantity of GH any one participant used and predicting expected changes in IGF levels.
Also note the "high" end GH users were taking 0.10 MG/KG of GH daily. So for a 100 KG mate thats a whopping 10mg or THIRTY IU every day! Moreover even at such high doses of GH upper end IGF levels PEAK at roughly 3 times baseline.
What does this mean IGF is an excellent marker used in the clinical setting (in addition to other factors) to determine the response to GH therapy. However the use of IGF to evaluate the "quality" (dose response curve) of a particular GH product is inherently flawed, IMO.
Consequently more accurate dose response estimates are obtained using peak GH levels. Such that for an average 100kg male a single 10IU dose of GH would be expected to INCREASE GH levels somewhere in the neighborhood of 15/20 ng/ml above baseline, assuming a concentration of greater than 90%. (Eli Lilly Humatrope internal data with a product concentration of 97.6%.)
Regs
jim