Complex process of bone disease evident in mastocytosis

Dec 12 2012

By Ingrid Grasmo, medwireNews Reporter

Patients with mastocytosis show elevated bone turnover that is associated with a higher mast cell load and advanced disease relative to individuals without the condition, suggest study findings.

According to Ghandi Damaj (Jules-Vernes University, Amiens, France) and co-authors, the findings indicate a complex process of bone turnover and the existence of a link between bone remodeling and mast cell burden in mastocytosis-related bone manifestations.

"Early detection of bone alterations is important to prevent progression to severe bone lesions and fractures," say the researchers in The American Journal of Medicine.

Results from 45 adult mastocytosis patients and 28 demographically matched healthy individuals who underwent radiographic imaging and bone mineral density (BMD) measurements revealed bone abnormalities in 75% of patients. Furthermore, 36% of patients had bone lesions, and 53% showed BMD alterations, of which 20% had osteoporosis and 33% had osteopenia.

Comparison of bone turnover markers between patients and controls revealed significantly higher levels of bone resorption and formation markers among patients (bone-specific alkaline phosphatase 18.1 vs 7.3 UI/L; C-telopeptide [CTX] 3199 vs 1508 pmol/L; deoxypyridinoline [DPyD] 5.43 vs 4.76 nmol/L; and osteoprotegerin [OPG] 5.1 vs 4.08 pmol/L).

"Increased levels of bone turnover markers may reflect an increase in the number of osteoclasts and osteoblasts due to expansion of mast cells, which is supported by the increased levels of circulating OPG," say Damaj and team.

The study also showed that higher levels of CTX and OPG were significantly associated with advanced systemic mastocytosis and tryptase levels, with the latter significantly correlated with bone resorption and remodeling markers.

Indeed, differentiation of indolent from advanced mastocytosis was possible using threshold values of 2800 pmol/L for CTX, 5.9 nmol/L for DPyD, and 5.5 pmol/L for OPG, with 67-77% sensitivity and 72-86% specificity.

The authors note that the observed variability in bone turnover marker levels support a complex process of bone turnover in mastocytosis-related bone manifestations.

"The role of bone turnover markers in the prediction and monitoring of BMD abnormalities and response to treatment remains to be defined in larger studies with a long and prospective follow-up," conclude the researchers.

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