Bone Abstracts

The effect of recombinant parathyroid hormone therapy as an anabolic agent has delivered great success in the treatment of osteoporosis. Although a treatment response is still defined in DXA terms, initial scans can fail to detect an increase in BMD since the collagen deposited in bone may not yet have mineralized. It is key therefore that an early response is detected biochemically and the physician can be reassured that the bone is not adynamic, the patient is compliant and in the majority of cases a DXA response will follow.

Methods: Four hundred and sixty patients who were commenced on recombinant PTH attending the bone health clinic had bone biochemistry performed at baseline and at follow up 3, 6 months and yearly there after. Bone Biochemistry included PINP (procollagen type 1 amino terminal peptide), osteocalcin (OC) and C telopeptide (Ctx).

Results: Eighty-five percent of the patients were female, mean age 65.5 (±11.15 S.D.) and males 66.1 (±9.4 S.D.). By 1 year significant changes had been made in Lumbar spine BMDs over baseline (P<0.01) similarly at the total hip changes were almost significant (P=0.055). Baseline PINP (35.1±21 ng/ml), OC (20.1±10ng/ml) and CTx (0.12±0.02 ng/ml) However marked increased in PINP were noted at 3 months (P<0.001), as in Osteocalcin (P<0.01) without a significant change was noted in serum CTx or calcium. Less that 5% of patients did not demonstrate a biochemical response. A small number who did demonstrate a bone marker rise failed to consequently demonstrate a BMD rise.

Conclusions: Bone biochemistry provides detailed information on specific activities relating to the osteoblasts ability to form bone and allows the physician to pin point potential difficulties with therapeutic interventions. They robustly indicate an early treatment response and correlate well with DXA results. They identify non responders early and those who have mineral deposition problems.