TNFRSF11B and osteoporosis: LMWHs (approximately 4000–6000 Dalton) cause less osteoporosis than standard-size UFHs (approximately 7000–25,000 Dalton), suggesting that UFHs are more inhibitory to OPG than are LMWHs because they are bulkier and sterically hinder OPG–RANKL interaction [31].