Bone turnover markers (CTX and P1NP): do you have a baseline?

Convinced my endocrinologist to order bone marker turnover tests as a baseline before my Reclast infusion which has been recommended by my breast cancer oncologist.

Today I went to Quest Labs with her order for these tests:

N-telopeptide Cross-Linked Serum (NTx)
C-telopeptide beta cross linked serum (CTx)
Procollagen type I Intact N-Terminal Propertied (P1NP)
Parathyroid Hormone Intact Without Calcium.

The Quest phlebotomist said she could not do a blood test on one of these tests, but it could be done with a urine test. She tried to contact my ordering physician to clarify blood or urine, but was unable to because it was too early. Decided to proceed with the 3 tests she could run. That's when problem #2 occurred. She could not successfully stick me despite 2 attempts (arm and hand). I can be a tough stick which is why I have a port for my chemotherapy. Unfortunately, Quest and most outpatient labs do not use ports.

I had fasted for 12 hours but drank 32 ounces of water between 6-7 am. My Quest appointment was at 7:30 am. Usually the hydration helps and the Quest phlebotomists have been successful on first sticks in the past. Unfortunately, the mastectomy/node biopsy means I should only use my left side. Today, alas, was not a successful blood draw.

Since there was confusion about one of the tests (urine or serum) and difficulty in sticking me, the phlebotomist and I agreed I should cancel that appointment, she would try to get more information from my doc, and then try again. Quest could do a urine test but not that specified serum test.

After that long-winded setup here's my actual question. I just found out my cancer infusion lab will accept this order for the bone markers even though the doctor is not on their staff. That will make it so much easier for me for the blood tests. If one of these tests must be a urine test, rather than a blood test, I'll get that elsewhere.

But my infusion appointment is at 2:30 pm. I cannot change this appointment as it's tied to seeing my oncologist immediately afterwards. From what I've read here these tests should be done after fasting but also ideally first thing in the morning. How unreliable would these tests be if done at 2:30 pm? I could probably hold out for an 8 hour fast. Or should I just hope for the best and go back and try again with conventional blood draws and needle sticks?

I guess yet another example of accepting things you can't control.

@prarysky

NTX can be measured from either serum or urine (usually the second morning void), so that’s likely the one the phlebotomist mentioned.

Of the tests, CTX is the most affected by timing and food. NTX varies a bit less. CTX reaches its lowest point between about 11am to 3pm, so it’s best done first thing in the morning after a fast (and ideally no biotin or collagen for 48 hours beforehand).

Fasting helps, but timing matters more. A 2:30pm draw will probably show a lower CTX, which makes trends harder to interpret. If blood draws are tough, a urine NTX is a good alternative - easier to collect and less time-sensitive. Ive read though, it shows more day-to-day variability and is generally less sensitive than CTX in tracking treatment response. Still, you have to make the best of the situation you’re in, and consistency in how it’s done will still give you useful information over time. It will be helpful to double-check with your ordering physician about timing and sample type to help ensure the most reliable results.

Sorry things haven’t been easy as you’re fighting on two fronts. Wishing you smooth sailing and good results ahead!

@mayblin Your information is so helpful! I just picked up my original order from the Quest Lab phlebotomist who confirmed that it is the NTX test that Quest will do as a urine test and not as the serum test which my doctor ordered.

So that's something I need to clarify with my doc and point out that most labs do the urine rather than serum, and I think the better results from the urine test must be why. Perhaps her hospital lab only does the serum version...I don't know. Haven't heard back from my doctor about whether she will change her order to urine. so will have to send her a message.

Meanwhile, the clock is ticking with that infusion appointment tomorrow. As much as I'd prefer to have these tests done using my port, it seems relying on the conventional blood draw early in the morning (as I tried to do yesterday) following a fast is what I must try again. Since consistency is also key, I can't rely on the availability of an infusion lab and port going forward.

Will wait a few days (to let my arm heal after uncooperative vein needle sticks) and try another lab and see if better luck there.

Thank you again for such solid information based on lots of research I know. What would we do without the help of people like you. You are truly a major part of our medical teams!

I have to question this generalization that CTX is highest at 7:30 AM, and only at that time. For someone who routinely gets up at 6 AM, that time to me would be different than for someone who does not get up until 11 AM; their bodies are on different rhythms/schedules.

@normahorn. that's an excellent thought. We do wake up a different times so our peak times could vary. My takeaway is that the important thing is to fast and test relatively early in the morning.

I've been told at Quest that they won't do a blood draw until 8:00 AM for P1NP and CTX if prescribed and paid by insurance.

@drsuefowler That's interesting because my Quest lab was willing to do those tests with a 7:30 am appointment. It never happened, though, because my vein blew so will try again another day.

I am taking eivinity romosozumab injections for 6 months now. 6 more months to go. Taking Calcium 1,200, Vitamin D 5,000 IU
I also took Biotin 100 tablets but I stopped 1 week before blood test. Did the Biotin affected my PINP & CTX reading ?
Before - PINP=92, CTX = 532
After 6 months - PINP=132, CTX = 806

One week should have been sufficient to eliminate the interference of serum biotin. Evenity shouldn't increase CTX. Something's amiss. Can you repeat the markers?

@alit did any of you took serum PTH test before sarting any medication??....most of the time paratahyroid gland is the culprit for overproduction of pth harmone which in turm cause osteopososis and if that is the cause of ostoeporosis then taking hRT injections can do more harm than good...it might lead to more bone loss