"...so large increases in GG may or may not be enough to produce a significant increase in the overall Globulin level. Perhaps someone can answer this."
For those who've had just the standard standard blood panels (and not a SPEP), an Albumin/Globulin Ratio is often indicated. Per the link below, "A high A/G ratio (>2.3) suggests underproduction of immunoglobulins (Gamma Globulins)." Looking to the inverse, it does not explicitly state that a low A/G ratio (<1.1) suggests overproduction of Gamma Globulins, but such a conclusion might be logical..? Not as accurate as a SPEP of course, but perhaps a starting point?