Biochemical markers of bone metabolism reflect osteoclastic and osteoblastic activity in multiple myeloma

In order to evaluate the use of recently developed assays of bone metabolis m in multiple myeloma we performed a histomorphometric study of bone biopsi es in 16 myeloma patients. Furthermore, we measured the levels of interleuk in-6 (IL-6), soluble IL-6 receptor (IL-6sR), IL-1 beta, tumour necrosis fac tor (TNF) alpha, TNF beta, and transforming growth factor (TGF) beta in mar row plasma aspirated from the biopsy area. Markers of bone resorption: The N-terminal telopeptide of collagen I (Ntx) in urine showed a strong positiv e correlation with the dynamic histomorphometric indices of bone resorption (r = 0.68-0.72). Slightly weaker correlations were observed between the dy namic indices of bone resorption and the C-terminal telopeptide of collagen I (ICTP) in serum (r = 0.57-0.62) and deoxypyridinoline (Dpyr) in urine (r = 0.54), whereas urinary pyridinoline (Pyr) did not correlate with the his tomorphometric findings. Markers of bone formation: Serum C-terminal propep tide of procollagen I (PICP) and serum bone-specific alkaline phosphatase ( bAP) showed significant correlations with the dynamic parameters of bone fo rmation (r = 0.57-0.58), whereas serum osteocalcin and serum total AP did n ot. Cytokines: Highly significant correlations were observed between marrow IL-6 and rates of bone resorption and activation frequency (r = 0.76-0.82) and with serum ICTP (r = 0.63). Minor, but also significant correlations w ere observed between the resorptive indices and IL-6sR and IL-1 beta. The d ata indicate that measurements of the biochemical markers of bone metabolis m may be useful in monitoring myeloma bone disease, and might thus be of us e for dose titration of bisphosphonate therapy.