BACKGROUND: Both atherosclerosis and osteoporosis often appear together, especially in the elderly; usually they are regarded as independent entities. Only recently epidemiological evidence occurred suggesting possible associations between these diseases. Several groups of factors (genetic, hormonal and biochemical) have been studied to account for this association. Among the genetic factors, apolipoprotein E has been studied most extensively; some results indicate that carriers of E4 allele are at increased risk of osteoporosis. A possible influence of plasma lipoproteins and of tissue ischaemia on bone metabolism has also been studied. AIM OF THE STUDY: To test the hypothesis that there is an association between apolipoprotein E, plasma lipid concentrations and bone mineral density. METHODS: We examined 18 apolipoprotein E2/2 and E4/4 homozygotes and 130 postmenopausal women. Bone mineral density and plasma triglycerides, total and HDL cholesterol were determined in both groups; in apolipoprotein E homozygotes biochemical markers of bone turnover were also measured. RESULTS: No significant differences in bone mineral density and bone remodelling were found between the E2/2 and E4/4 homozygotes. A negative correlation between lumbar spine bone mineral density and cholesterol and triglyceride concentrations (r = 0.20-0.39) was observed both in postmenopausal women and apolipoprotein E homozygotes. CONCLUSION: We didn't observe any association of apolipoprotein E genotype with bone mineral density and biochemical markers of bone metabolism. A negative association between plasma lipid concentrations and bone mineral density supports the hypothesis of harmful effect of hyperlipidaemia on bone metabolism.

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