Biologic tolerance of two different low molecular weight heparins.

Heparin preparations have been used for prophylaxis and treatment of deep vein thrombosis for many years. Several biologic effects of heparin are known. Since 1978, there have been several reports about reversible elevation in serum values of AST and ALT in patients and healthy volunteers given heparin in small and high doses. Few studies report similar events in patients given LMW heparins. Results of two randomized studies (A and B) comprising 456 patients undergoing THR are presented. Two different compounds of LMW heparin (Logiparin or Enoxaparin) were used for thromboprophylaxis. Significant elevation during the postoperative period of AST and AP in study A, and AST, ALT, AP, LDH, and CK in study B were demonstrated in patients given LMW heparins in both studies. In study A the percentages of patients with normal preoperative values who reached pathologic values were 35% for AST and 15% for AP. In study B the percentages of patients with normal preoperative values who reached pathologic values were 36% for AST, 17% of ALT, 14% for AP, and 36% for LDH. The possible biologic mechanisms and the clinical perspectives are discussed. In all cases the changes in the liver enzymes returned to preoperative levels within 14 days.