I see. Hopefully your doc figures out whether or not there is a secondary cause and finds a best solution going forward!

Having food before blood drawing for bone marker testing is known to affect results, especially with CTX. According to one published paper, "Feeding/fasting state has an impact on BTMs. Morning feeding decreased PINP (3.8%), OC (4.1%), uNTX (7.9%), and CTX (17.8%) while bone ALP did not vary significantly". Your cup of coffee with sugar may or maynot cause too much change in CTX. With regards to time of testing, "CTX showed the greatest diurnal fluctuation. Peak levels were observed between 0130 and 0430 hours and were 40% to 60% higher than the 24-hour mean, while the nadir was observed between 1100 and 1500 hours. The lowest value was 40% to 60% below the 24-hour mean". This is probably why Dr. McCormick recommends to get btms done within first hour of waking up, if possible.