Endocrine Abstracts

The TNF members sRANK-L & Osteoprotegerin (OPG) are essential paracrine mediators of osteoclast function in vitro. The aim of this study was to establish the relationship between 25-hydroxyvitamin D and sRANK-L and OPG in plasma of osteoporotic patients.

The study population consisted of 185 osteoporotic women (mean age 62.4 years), with bone mineral density (BMD) more than 2.5 SD below the young adult value, and 185 age-matched controls, with normal bone mineral density. BMD was measured by LUNAR DEXA.

Plasma sRANK-L and OPG were assayed by ELISA kits from Biomedica Gruppe supplied by Quidel Diagnostics and 25- hydroxyvitamin D by ELISA from the IDS OCTEA

The following correlations were obtained in the osteoporotics:

1. A negative correlation was shown between 25- hydroxyvitamin D and OPG (r = -0.171,P<0.01).

2. A negative correlation was shown between 25- hydroxyvitamin D and sRANK-l (r = -

0.118,P<0.05).

No correlations were found in the non-osteoporotic group:

The mean plasma 25-hydroxyvitamin D concentration was lower in osteoporotic women than controls. 85 osteoporotic women (45.95% ) had 25- hydroxyvitamin D levels below the reference level for this assay (47 - 144 nmols/L). The mean OPG in this group was 23.128 pmol/L compared to those with normal plasma 25- hydroxyvitamin D concentrations 14.98 pmol/L. The mean sRANK-L was 0.93 pmol/L compared to those osteoporotics with normal plasma 25- hydroxyvitamin D concentrations 0.45 pmol/L.

On the basis of the results of this study, we propose a model whereby lower vitamin D levels are associated with higher bone turnover due to increased sRANK-L stimulating osteoclastogenesis.