The clinical importance of antithrombin was directly proved by the description of the first hereditary antithrombin deficiency /HAD/ in 1965. Several other families have been studied since that time. Two main types of /HAD/ can be discerned. In one, both immunologic and fuctional methods reveal low level of antithrombin in the affected members. Some biochemical observations suggest the heterogenity even of this type of HAD. Oral anticoagulants seem effective in the treatment and prophylaxis of these patients. Thus, determination of antithrombin level should be performed in all young thrombotic patients especially. with prevalence of thromboembolism in the family. The second type of HAD, the congenital functional abnormality of antithrombin is very rare. Oestrogenic hormones can decrease the synthesis of antithrombin. This observation might be connected with •the thromboembolic complications of oral contraceptives. More data ar needed to evaluate the usefulness of monitoring the antithrombin level in the course of contraceptive treatment to avoid these complications. Decreased antithrombin levels and detection of antithrombin-complexes can provide useful information in the diagnosis of hypercoagulable states. Due to the methodologic development experienced in the last few years, one can expect a rapid rise of clinical investigations bringing about a better knowledge of clinical significance.
Ischemic colitis associated with hormonal contraceptive treatment delivered via vaginal ring
