Bone collagen, mineral and trace element composition, histomorphometry and urinary hydroxyproline excretion in...

(1) We examined the possibility that enhanced fragility of the bony skeleton in alcohol abusers may be a consequence of a reduction in collagen composition. Male rats were fed a liquid diet containing 36% of total calories as ethanol; controls were pair-fed iso-caloric glucose. At 3, 7 and 14 days of treatment, collagen contents of tibia were unaltered, but small and significant reductions (15-30%) were observed at 28 and 42 days of treatment. Urinary hydroxyproline excretion was increased by 40-60% at 42 days of treatment, suggesting enhanced collagen degradation. (2) Bones of rats treated with ethanol for 42 days had significantly reduced mineral content (approximately 20%) with accompanying reductions in phosphate, calcium, copper and magnesium, but not sodium or potassium. Water content was unaltered, but tibial zinc and iron were increased by approximately 15%. (3) Histomorphometric analysis of bones taken at 42 days showed significant reductions in cortical bone thickness of lower tibia (by 28%). The thickness of the upper cortices and cancellous bone of the tibia was unaffected. Reductions in trabecular bone volume (approx. 25%) did not achieve statistical significance. (4) These observations are consistent with the known enhanced fragility of bones in alcoholic rats. The regional susceptibility of the tibia may be related to reduced load bearing as a result of muscle atrophy.