Your doctor may order a test for measurement of N-telopeptide (NTx). It is a bone turnover marker that can measured from a urine or blood sample. N-telopeptide is a breakdown product of collagen. Therefore, NTx is an indirect measure of the rate of bone breakdown.
The average level measured in the urine for premenopausal women is 35 (the units are a bit confusing so only the values are presented that are NTx divided by creatinine measurement).
The average value of 35 plus or minus one standard deviation of 15 provides the normal range of NTx of 20 to 50. The higher the level is of NTx, the higher the risk is of bone loss.
All the osteoporosis medicine that target the bone breakdown cells lower the rate of bone breakdown. The potency of the medicine may be reflected in the degree of lowering a bone turnover marker like NTx.
Measurement of NTx may be helpful to assess rate of bone turnover and risk of bone loss, monitor response to therapy, and use in combination with your DXA scan results to assess fracture risk.