The needle length is the same (1/2 inch) and the only difference is that one is thinner (31g) and you have gone from 2 weekly injections to 3 weekly injections. Would only the diameter of the needle be able to make all this change? How long did you take the test in the lab after you started applying 3x / week? The time and day you collected the blood can also give this change.I had the same issue with going from 50mg twice a week with a 1/2in 29 gage needle to 32mg three times a week with a 5/16in 31 gage needle. Went from a TT of 846 to a TT of 531. I believe it has something to do with going from shallow IM to SQ.