I Have Had And Used Prescription Norco 10/25 For Several

I have had and used prescription Norco 10/25 for several years because of lombar spine problems. I can take 4 in a 24 hr periof but never do. I usually take 2 or less pills a day. Now my doctor wants me to take a blood test to see the level of Norco in my body. IT won't be as much as he has prescribed and my friends say I will be cut off my prescription/